diff --git a/.github/scripts/build.sh b/.github/scripts/build.sh
index 329919ee5d..e65bce4afd 100755
--- a/.github/scripts/build.sh
+++ b/.github/scripts/build.sh
@@ -5,9 +5,9 @@ echo Building Chez Scheme...
 make
 case $MACH in
   *a6nt)
-    curl -Ls https://github.com/burgerrg/win-iconv/releases/download/v0.0.9/iconv-x64.dll > $TARGET_MACHINE/bin/$TARGET_MACHINE/iconv.dll
+    curl -Ls https://github.com/burgerrg/win-iconv/releases/download/v0.0.9/iconv-x64.dll > "$TARGET_MACHINE"/bin/"$TARGET_MACHINE"/iconv.dll
     ;;
   *i3nt)
-    curl -Ls https://github.com/burgerrg/win-iconv/releases/download/v0.0.9/iconv-x86.dll > $TARGET_MACHINE/bin/$TARGET_MACHINE/iconv.dll
+    curl -Ls https://github.com/burgerrg/win-iconv/releases/download/v0.0.9/iconv-x86.dll > "$TARGET_MACHINE"/bin/"$TARGET_MACHINE"/iconv.dll
     ;;
 esac
diff --git a/.github/scripts/matting.sh b/.github/scripts/matting.sh
new file mode 100755
index 0000000000..81a85d8130
--- /dev/null
+++ b/.github/scripts/matting.sh
@@ -0,0 +1,12 @@
+#!/bin/bash
+# We don't use grep because on Windows, it doesn't flush its output.
+live=no
+while read -r line; do
+    echo "$line" >> mats.out
+    if [[ "$line" = matting* ]]; then
+	echo "$line"
+	live=yes
+    elif [[ "$live" = no ]]; then
+	echo "$line"
+    fi
+done
diff --git a/LOG b/LOG
index d650a12488..abb720a18f 100644
--- a/LOG
+++ b/LOG
@@ -1990,3 +1990,52 @@
     compress_io.c, new_io.c, externs.h,
     bytevector.ms, mats/Mf-base, root-experr*
     io.stex, objects.stex, release_notes.stex
+- fix fasl-read signature
+    primdata.ss
+- console I/O on Windows now supports Unicode characters in the BMP
+    expeditor.c, new-io.c, release_notes.stex
+- the collector now releases bignum temporaries in the collector
+  rather than relocating them so we don't keep around huge bignum
+  temporaries forever.
+     gc.c
+- removed the presumably useless vector-handling code from load()
+  which used to be required to handle fasl groups.
+     scheme.c
+- object files are no longer compressed as a whole, and the parameter
+  compile-compressed is no longer defined.  instead, the individual
+  fasl objects within an object file are compressed whenever the
+  new parameter fasl-compressed is set to its default value, #t.
+  this allows the fasl reader to seek past portions of an object
+  file that are not of interest, i.e., visit-only code and data
+  when "revisiting" an object file and revisit-only code and data
+  when "visiting" an object file.  the compressed portions are
+  compressed using the format and level specified by the compress-format
+  and compress-level parameters.  the C-coded fasl reader and
+  boot-file loader no longer handle compressed files; these are
+  handled, less efficiently, by the Scheme entry point (fasl-read).
+  a warning exception is raised the first time a program attempts
+  to create or read a compressed fasl file.
+    7.ss, s/Mf-base, back.ss, bytevector.ss, cmacros.ss, compile.ss,
+    fasl-helpers.ss, fasl.ss, primdata.ss, strip.ss, syntax.ss,
+    externs.h, fasl.c, gc.c, scheme.c, thread.c,
+    mats/6.ms, mats/7.ms, mats/bytevector.ms, mats/misc.ms, patch*,
+    root-experr*,
+    intro.stex, use.stex, io.stex, system.stex,
+    release_notes.stex
+- added begin wrappers around many of the Scheme source files that
+  contained multiple expressions to cut down the number of top-level
+  fasl objects and increase compressibility.  also removed the
+  string filenames for debugging at the start of each file that had
+  one---these are best inserted universally by a modified compile-file
+  during a debugging session when desired.  also removed unnecessary
+  top-level placeholder definitions for the assignments that follow.
+    4.ss, 5_1.ss, 5_2.ss, 5_3.ss, 5_7.ss, 6.ss, 7.ss, bytevector.ss,
+    cafe.ss, cback.ss, compile.ss, cp0.ss, cpcommonize.ss, cpletrec.ss,
+    cpnanopass.ss, cprep.ss, cpvalid.ss, date.ss, engine.ss, enum.ss,
+    env.ss, event.ss, exceptions.ss, expeditor.ss, fasl.ss, foreign.ss,
+    format.ss, front.ss, ftype.ss, inspect.ss, interpret.ss, io.ss,
+    library.ss, mathprims.ss, newhash.ss, pdhtml.ss, pretty.ss,
+    prims.ss, primvars.ss, print.ss, read.ss, record.ss, reloc.ss,
+    strnum.ss, syntax.ss, trace.ss
+- updated bullyx patches
+    patch*
diff --git a/c/expeditor.c b/c/expeditor.c
index 55ce40af5f..42963e66ac 100644
--- a/c/expeditor.c
+++ b/c/expeditor.c
@@ -77,7 +77,7 @@ static ptr s_ee_read_char(IBOOL blockp) {
   ptr tc;
 #endif /* PTHREADS */
   BOOL succ;
-  static char buf[10];
+  static wchar_t buf[10];
   static int bufidx = 0;
   static int buflen = 0;
   static int rptcnt = 0;
@@ -95,7 +95,7 @@ static ptr s_ee_read_char(IBOOL blockp) {
     if (!blockp) {
        DWORD NumberOfEvents;
        if (!GetNumberOfConsoleInputEvents(hStdin, &NumberOfEvents))
-         S_error1("expeditor", "error getting console info: ~a",
+         S_error1("expeditor", "error getting console input: ~a",
                     S_LastErrorString());
        if (NumberOfEvents == 0) return Sfalse;
     }
@@ -104,13 +104,13 @@ static ptr s_ee_read_char(IBOOL blockp) {
     tc = get_thread_context();
     if (DISABLECOUNT(tc) == FIX(0)) {
         deactivate_thread(tc);
-        succ = ReadConsoleInput(hStdin, irInBuf, 1, &cNumRead);
+        succ = ReadConsoleInputW(hStdin, irInBuf, 1, &cNumRead);
         reactivate_thread(tc);
     } else {
-        succ = ReadConsoleInput(hStdin, irInBuf, 1, &cNumRead);
+        succ = ReadConsoleInputW(hStdin, irInBuf, 1, &cNumRead);
     }
 #else /* PTHREADS */
-    succ = ReadConsoleInput(hStdin, irInBuf, 1, &cNumRead);
+    succ = ReadConsoleInputW(hStdin, irInBuf, 1, &cNumRead);
 #endif /* PTHREADS */
 
 
@@ -125,10 +125,10 @@ static ptr s_ee_read_char(IBOOL blockp) {
         KEY_EVENT_RECORD ker = irInBuf[0].Event.KeyEvent; 
         rptcnt = ker.wRepeatCount;
         if (ker.bKeyDown) {
-          char c;
+          wchar_t c;
 
-          if (c = ker.uChar.AsciiChar) {
-           /* translate ^@ 2) and ^<space> to nul */
+          if (c = ker.uChar.UnicodeChar) {
+            /* translate ^<space> to nul */
             if (c == 0x20 && (ker.dwControlKeyState & (LEFT_CTRL_PRESSED|RIGHT_CTRL_PRESSED)))
               buf[0] = 0;
             else
@@ -508,12 +508,15 @@ static ptr s_ee_get_clipboard(void) {
   ptr x = S_G.null_string;
 
   if (OpenClipboard((HWND)0)) {
-    HANDLE h = GetClipboardData(CF_TEXT);
-     
-    if (h != (HANDLE *)0) {
-      char *s = (char *)GlobalLock(h);
-      if (s != (char *)0) x = Sstring(s);
-      GlobalUnlock(h);
+    HANDLE h = GetClipboardData(CF_UNICODETEXT);
+    if (h != NULL) {
+      wchar_t *w = (wchar_t*)GlobalLock(h);
+      if (w != NULL) {
+        char *s = Swide_to_utf8(w);
+        x = Sstring_utf8(s, -1);
+        free(s);
+        GlobalUnlock(h);
+      }
     }
     CloseClipboard();
   }
@@ -522,8 +525,8 @@ static ptr s_ee_get_clipboard(void) {
 }
 
 static void s_ee_write_char(wchar_t c) {
-  if (c > 255) c = '?';
-  putchar(c);
+  DWORD n;
+  WriteConsoleW(hStdout, &c, 1, &n, NULL);
 }
 
 #else /* WIN32 */
diff --git a/c/externs.h b/c/externs.h
index 2a67b3d906..e10038dfd2 100644
--- a/c/externs.h
+++ b/c/externs.h
@@ -107,10 +107,9 @@ extern void S_phantom_bytevector_adjust PROTO((ptr ph, uptr new_sz));
 
 /* fasl.c */
 extern void S_fasl_init PROTO((void));
-ptr S_fasl_read PROTO((ptr file, IBOOL gzflag, IFASLCODE situation, ptr path));
+ptr S_fasl_read PROTO((INT fd, IFASLCODE situation, ptr path));
 ptr S_bv_fasl_read PROTO((ptr bv, int ty, uptr offset, uptr len, ptr path));
-/* S_boot_read's f argument is really gzFile, but zlib.h is not included everywhere */
-ptr S_boot_read PROTO((glzFile file, const char *path));
+ptr S_boot_read PROTO((INT fd, const char *path));
 char *S_format_scheme_version PROTO((uptr n));
 char *S_lookup_machine_type PROTO((uptr n));
 extern void S_set_code_obj PROTO((char *who, IFASLCODE typ, ptr p, iptr n,
diff --git a/c/fasl.c b/c/fasl.c
index 02e162f14e..1536c91e40 100644
--- a/c/fasl.c
+++ b/c/fasl.c
@@ -18,15 +18,19 @@
  *
  * <fasl-file> -> <fasl-group>*
  *
- * <fasl-group> -> <fasl header><fasl-object>*
+ * <fasl-group> -> <fasl-header><fasl-object>*
  *
  * <fasl-header> -> {header}\0\0\0chez<uptr version><uptr machine-type>(<bootfile-name> ...)
  *
  * <bootfile-name> -> <octet char>*
  *
- * <fasl-object> -> <situation>{fasl-size}<uptr size><fasl> # size is the size in bytes of the following <fasl>
+ * <fasl-object> -> <situation><uptr size><pcfasl> # size is the size in bytes of <pcfasl>
  *
- * <situation> -> {visit}{revisit}{visit-revisit}
+ * <situation> -> {visit} | {revisit} | {visit-revisit}
+ *
+ * <pcfasl> -> <compressed><uptr uncompressed-size><compressed fasl> | {uncompressed}<fasl>
+ * 
+ * <compressed> -> {gzip} | {lz4}
  *
  * <fasl> -> {pair}<uptr n><fasl elt1>...<fasl eltn><fasl last-cdr>
  *
@@ -191,16 +195,15 @@
 #include NAN_INCLUDE
 #endif
 
-#define UFFO_TYPE_GZ 1
 #define UFFO_TYPE_FD 2
 #define UFFO_TYPE_BV 3
 
-/* we do our own buffering size gzgetc is slow */
+#define PREPARE_BYTEVECTOR(bv,n) {if (bv == Sfalse || Sbytevector_length(bv) < (n)) bv = S_bytevector(n);}
+
 typedef struct unbufFaslFileObj {
   ptr path;
   INT type;
   INT fd;
-  glzFile file;
 } *unbufFaslFile;
 
 typedef struct faslFileObj {
@@ -214,7 +217,7 @@ typedef struct faslFileObj {
 /* locally defined functions */
 static INT uf_read PROTO((unbufFaslFile uf, octet *s, iptr n));
 static octet uf_bytein PROTO((unbufFaslFile uf));
-static uptr uf_uptrin PROTO((unbufFaslFile uf));
+static uptr uf_uptrin PROTO((unbufFaslFile uf, INT *bytes_consumed));
 static ptr fasl_entry PROTO((ptr tc, IFASLCODE situation, unbufFaslFile uf));
 static ptr bv_fasl_entry PROTO((ptr tc, ptr bv, IFASLCODE ty, uptr offset, uptr len, unbufFaslFile uf));
 static void fillFaslFile PROTO((faslFile f));
@@ -295,20 +298,15 @@ void S_fasl_init() {
 #endif
 }
 
-ptr S_fasl_read(ptr file, IBOOL gzflag, IFASLCODE situation, ptr path) {
+ptr S_fasl_read(INT fd, IFASLCODE situation, ptr path) {
   ptr tc = get_thread_context();
   ptr x; struct unbufFaslFileObj uffo;
 
  /* acquire mutex in case we modify code pages */
   tc_mutex_acquire()
   uffo.path = path;
-  if (gzflag) {
-    uffo.type = UFFO_TYPE_GZ;
-    uffo.file = S_gzxfile_gzfile(file);
-  } else {
-    uffo.type = UFFO_TYPE_FD;
-    uffo.fd = GET_FD(file);
-  }
+  uffo.type = UFFO_TYPE_FD;
+  uffo.fd = fd;
   x = fasl_entry(tc, situation, &uffo);
   tc_mutex_release()
   return x;
@@ -327,18 +325,16 @@ ptr S_bv_fasl_read(ptr bv, int ty, uptr offset, uptr len, ptr path) {
   return x;
 }
 
-ptr S_boot_read(glzFile file, const char *path) {
+ptr S_boot_read(INT fd, const char *path) {
   ptr tc = get_thread_context();
   struct unbufFaslFileObj uffo;
 
   uffo.path = Sstring_utf8(path, -1);
-  uffo.type = UFFO_TYPE_GZ;
-  uffo.file = file;
+  uffo.type = UFFO_TYPE_FD;
+  uffo.fd = fd;
   return fasl_entry(tc, fasl_type_visit_revisit, &uffo);
 }
 
-#define GZ_IO_SIZE_T unsigned int
-
 #ifdef WIN32
 #define IO_SIZE_T unsigned int
 #else /* WIN32 */
@@ -346,28 +342,15 @@ ptr S_boot_read(glzFile file, const char *path) {
 #endif /* WIN32 */
 
 static INT uf_read(unbufFaslFile uf, octet *s, iptr n) {
-  iptr k; INT errnum;
+  iptr k;
   while (n > 0) {
     uptr nx = n;
 
 #if (iptr_bits > 32)
-  if ((WIN32 || gzflag) && (unsigned int)nx != nx) nx = 0xffffffff;
+  if (WIN32 && (unsigned int)nx != nx) nx = 0xffffffff;
 #endif
 
     switch (uf->type) {
-      case UFFO_TYPE_GZ:
-        k = S_glzread(uf->file, s, (GZ_IO_SIZE_T)nx);
-        if (k > 0)
-          n -= k;
-        else if (k == 0)
-          return -1;
-        else {
-          S_glzerror(uf->file, &errnum);
-          S_glzclearerr(uf->file);
-          if (errnum != Z_ERRNO || errno != EINTR)
-            S_error1("", "error reading from ~a", uf->path);
-        }
-        break;
       case UFFO_TYPE_FD:
         k = READ(uf->fd, s, (IO_SIZE_T)nx);
         if (k > 0)
@@ -394,11 +377,6 @@ int S_fasl_stream_read(void *stream, octet *dest, iptr n)
 
 static void uf_skipbytes(unbufFaslFile uf, iptr n) {
   switch (uf->type) {
-    case UFFO_TYPE_GZ:
-       if (S_glzseek(uf->file, (long)n, SEEK_CUR) == -1) {
-         S_error1("", "error seeking ~a", uf->path);
-       }
-       break;
     case UFFO_TYPE_FD:
        if (LSEEK(uf->fd, n, SEEK_CUR) == -1) {
          S_error1("", "error seeking ~a", uf->path);
@@ -414,12 +392,14 @@ static octet uf_bytein(unbufFaslFile uf) {
   return buf[0];
 }
 
-static uptr uf_uptrin(unbufFaslFile uf) {
+static uptr uf_uptrin(unbufFaslFile uf, INT *bytes_consumed) {
   uptr n, m; octet k;
 
+  if (bytes_consumed) *bytes_consumed = 1;
   k = uf_bytein(uf);
   n = k & 0x7F;
   while (k & 0x80) {
+    if (bytes_consumed) *bytes_consumed += 1;
     k = uf_bytein(uf);
     m = n << 7;
     if (m >> 7 != n) toolarge(uf->path);
@@ -454,7 +434,9 @@ char *S_lookup_machine_type(uptr n) {
 
 static ptr fasl_entry(ptr tc, IFASLCODE situation, unbufFaslFile uf) {
   ptr x; ptr strbuf = S_G.null_string;
-  octet tybuf[1]; IFASLCODE ty, fmt; iptr size;
+  octet tybuf[1]; IFASLCODE ty; iptr size;
+  /* gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28) co-locates buf and x if we put the declaration of buf down where we use it */
+  octet buf[SBUFSIZ];
 
   for (;;) {
     if (uf_read(uf, tybuf, 1) < 0) return Seof_object; 
@@ -473,10 +455,10 @@ static ptr fasl_entry(ptr tc, IFASLCODE situation, unbufFaslFile uf) {
           uf_bytein(uf) != 'z')
         S_error1("", "malformed fasl-object header (missing magic word) found in ~a", uf->path);
     
-      if ((n = uf_uptrin(uf)) != scheme_version)
+      if ((n = uf_uptrin(uf, (INT *)0)) != scheme_version)
         S_error2("", "incompatible fasl-object version ~a found in ~a", S_string(S_format_scheme_version(n), -1), uf->path);
     
-      if ((n = uf_uptrin(uf)) != machine_type_any && n != machine_type)
+      if ((n = uf_uptrin(uf, (INT *)0)) != machine_type_any && n != machine_type)
         S_error2("", "incompatible fasl-object machine-type ~a found in ~a", S_string(S_lookup_machine_type(n), -1), uf->path);
     
       if (uf_bytein(uf) != '(')
@@ -500,30 +482,66 @@ static ptr fasl_entry(ptr tc, IFASLCODE situation, unbufFaslFile uf) {
         return (ptr)0;
     }
 
-    fmt = uf_bytein(uf);
-    if ((fmt != fasl_type_fasl_size) && (fmt != fasl_type_vfasl_size))
-      S_error1("", "malformed fasl-object header (missing fasl-size) found in ~a", uf->path);
-  
-    size = uf_uptrin(uf);
+    size = uf_uptrin(uf, (INT *)0);
   
     if (ty == situation || situation == fasl_type_visit_revisit || ty == fasl_type_visit_revisit) {
-      struct faslFileObj ffo; octet buf[SBUFSIZ];
+      struct faslFileObj ffo;
+      ptr bv; IFASLCODE kind;
 
-      ffo.size = size;
-      
-      if (fmt == fasl_type_vfasl_size) {
-        if (S_vfasl_boot_mode) {
-          /* compact every time, because running previously loaded
-             boot code may have interned symbols, for example */
-          S_vfasl_boot_mode = 1;
-          Scompact_heap();
+      ty = uf_bytein(uf);
+      kind = uf_bytein(uf); /* fasl or vfasl */
+
+      if ((kind == fasl_type_vfasl) && S_vfasl_boot_mode) {
+        /* compact every time, because running previously loaded
+           boot code may have interned symbols, for example */
+        Scompact_heap();
+      }
+
+      switch (ty) {
+        case fasl_type_gzip:
+        case fasl_type_lz4: {
+          ptr result; INT bytes_consumed;
+          iptr dest_size = uf_uptrin(uf, &bytes_consumed);
+          iptr src_size = size - (2 + bytes_consumed); /* adjust for u8 compression type, u8 fasl type, and uptr dest_size */
+
+          PREPARE_BYTEVECTOR(SRCBV(tc), src_size);
+          PREPARE_BYTEVECTOR(DSTBV(tc), dest_size);
+          if (uf_read(uf, &BVIT(SRCBV(tc),0), src_size) < 0)
+            S_error1("", "unexpected eof in fasl file ~a", uf->path);
+          result = S_bytevector_uncompress(DSTBV(tc), 0, dest_size, SRCBV(tc), 0, src_size,
+                      (ty == fasl_type_gzip ? COMPRESS_GZIP : COMPRESS_LZ4));
+          if (result != FIX(dest_size)) {
+            if (Sstringp(result)) S_error2("fasl-read", "~@?", result, SRCBV(tc));
+            S_error3("fasl-read", "uncompressed size ~s for ~s is smaller than expected size ~s", result, SRCBV(tc), FIX(dest_size));
+          }
+          ffo.size = dest_size;
+          ffo.next = ffo.buf = &BVIT(DSTBV(tc),0);
+          ffo.end = &BVIT(DSTBV(tc),dest_size);
+          ffo.uf = uf;
+          bv = DSTBV(tc);
+          break;
         }
-        x = S_vfasl((ptr)0, uf, 0, ffo.size);
-      } else {
-        ffo.buf = buf;
-        ffo.next = ffo.end = ffo.buf;
-        ffo.uf = uf;
-        faslin(tc, &x, S_G.null_vector, &strbuf, &ffo);
+        case fasl_type_uncompressed: {
+          ffo.size = size - 2; /* adjust for u8 compression type and u8 fasl type */
+          ffo.next = ffo.end = ffo.buf = buf;
+          bv = (ptr)0;
+          ffo.uf = uf;
+          break;
+        }
+        default:
+          S_error2("", "malformed fasl-object header (missing possibly-compressed, got ~s) found in ~a", FIX(ty), uf->path);
+          return (ptr)0;
+      }
+      switch (kind) {
+        case fasl_type_fasl:
+          faslin(tc, &x, S_G.null_vector, &strbuf, &ffo);          
+          break;
+        case fasl_type_vfasl:
+          x = S_vfasl(bv, uf, 0, ffo.size);
+          break;
+        default:
+          S_error2("", "malformed fasl-object header (got ~s) found in ~a", FIX(ty), uf->path);
+          return (ptr)0;
       }
       S_flush_instruction_cache(tc);
       return x;
@@ -537,15 +555,17 @@ static ptr bv_fasl_entry(ptr tc, ptr bv, int ty, uptr offset, uptr len, unbufFas
   ptr x; ptr strbuf = S_G.null_string;
   struct faslFileObj ffo;
 
-  if (ty == fasl_type_vfasl_size) {
+  if (ty == fasl_type_vfasl) {
     x = S_vfasl(bv, (ptr)0, offset, len);
-  } else {
+  } else if (ty == fasl_type_fasl) {
     ffo.size = len;
     ffo.next = ffo.buf = &BVIT(bv, offset);
     ffo.end = &BVIT(bv, offset + len);
     ffo.uf = uf;
     
     faslin(tc, &x, S_G.null_vector, &strbuf, &ffo);
+  } else {
+    S_error1("", "bad entry type (got ~s)", FIX(ty));
   }
 
   S_flush_instruction_cache(tc);
diff --git a/c/new-io.c b/c/new-io.c
index 67fef8fefa..d1ab66bb1c 100644
--- a/c/new-io.c
+++ b/c/new-io.c
@@ -413,6 +413,26 @@ ptr S_close_fd(ptr file, IBOOL gzflag) {
 
 #ifdef WIN32
 #define IO_SIZE_T unsigned int
+static HANDLE hStdin = NULL;
+static iptr read_console(char* buf, unsigned size) {
+  static char u8buf[1024];
+  static int u8i = 0;
+  static int u8n = 0;
+  iptr n = 0;
+  do {
+    for (; size > 0 && u8n > 0; size--, u8n--, n++)
+      *buf++ = u8buf[u8i++];
+    if (n == 0 && size > 0) {
+      wchar_t wbuf[256];
+      DWORD wn;
+      if (!ReadConsoleW(hStdin, wbuf, 256, &wn, NULL) || wn == 0)
+        return 0;
+      u8n = WideCharToMultiByte(CP_UTF8, 0, wbuf, wn, u8buf, 1024, NULL, NULL);
+      u8i = 0;
+    }
+  } while (n == 0);
+  return n;
+}
 #else /* WIN32 */
 #define IO_SIZE_T size_t
 #endif /* WIN32 */
@@ -434,17 +454,28 @@ ptr S_bytevector_read(ptr file, ptr bv, iptr start, iptr count, IBOOL gzflag) {
 
   LOCKandDEACTIVATE(tc, bv)
 #ifdef WIN32
-  if (!gzflag && fd == 0) {
+  if (!gzflag && fd == 0 && hStdin != NULL) {
     DWORD error_code;
     SetConsoleCtrlHandler(NULL, TRUE);
     SetLastError(0);
-    m = _read(0, &BVIT(bv,start), (IO_SIZE_T)count);
+    m = read_console(&BVIT(bv,start), (IO_SIZE_T)count);
     error_code = GetLastError();
-    SetConsoleCtrlHandler(NULL, FALSE);
     if (m == 0 && error_code == 0x3e3) {
+      /* Guard against Windows calling the ConsoleCtrlHandler after we
+       * turn it back on by waiting a bit. */
+      Sleep(1);
+#ifdef PTHREADS
+      /* threaded io.ss doesn't handle interrupts because
+       * with-tc-mutex disables them, so bail out. */
+      SetConsoleCtrlHandler(NULL, FALSE);
+      REACTIVATEandUNLOCK(tc, bv)
+      S_noncontinuable_interrupt();
+#else
       KEYBOARDINTERRUPTPENDING(tc) = Strue;
       SOMETHINGPENDING(tc) = Strue;
+#endif
     }
+    SetConsoleCtrlHandler(NULL, FALSE);
   } else
 #endif /* WIN32 */
   {
@@ -770,10 +801,19 @@ void S_new_io_init() {
     S_set_symbol_value(S_intern((const unsigned char *)"$c-bufsiz"), Sinteger(SBUFSIZ));
   }
 #ifdef WIN32
+  { /* Get the console input handle for reading Unicode characters */
+    HANDLE h;
+    DWORD mode;
+    if ((h = GetStdHandle(STD_INPUT_HANDLE)) != INVALID_HANDLE_VALUE
+        && GetConsoleMode(h, &mode))
+      hStdin = h;
+  }
  /* transcoder, if any, does its own cr, lf translations */
   _setmode(_fileno(stdin), O_BINARY);
   _setmode(_fileno(stdout), O_BINARY);
   _setmode(_fileno(stderr), O_BINARY);
+  /* Set the console output to handle UTF-8 */
+  SetConsoleOutputCP(CP_UTF8);
 #endif /* WIN32 */
 }
 
diff --git a/c/scheme.c b/c/scheme.c
index 6835e1ccff..d204edc028 100644
--- a/c/scheme.c
+++ b/c/scheme.c
@@ -19,15 +19,17 @@
 #include <setjmp.h>
 #include <limits.h>
 #ifdef WIN32
+#include <io.h>
 #include <time.h>
 #else
 #include <sys/time.h>
 #endif
+#include <fcntl.h>
 #include <stddef.h>
 
-extern iptr vfasl_load_time;
-extern iptr vfasl_fix_time;
-extern iptr vfasl_relocs;
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif /* O_BINARY */
 
 static INT boot_count;
 static IBOOL verbose;
@@ -44,7 +46,7 @@ static void idiot_checks PROTO((void));
 static INT run_script PROTO((const char *who, const char *scriptfile, INT argc, const char *argv[], IBOOL programp));
 
 extern void scheme_include(void);
-  
+
 static void main_init() {
     ptr tc = get_thread_context();
     ptr p;
@@ -560,7 +562,7 @@ static IBOOL next_path(path, name, ext, sp, dsp) char *path; const char *name, *
 /* BOOT FILES */
 
 typedef struct {
-  glzFile file;
+  INT fd;
   char path[PATH_MAX];
 } boot_desc;
 
@@ -568,8 +570,9 @@ typedef struct {
 static boot_desc bd[MAX_BOOT_FILES];
 
 /* locally defined functions */
-static uptr zget_uptr PROTO((glzFile file, uptr *pn));
-static INT zgetstr PROTO((glzFile file, char *s, iptr max));
+static octet get_u8 PROTO((INT fd));
+static uptr get_uptr PROTO((INT fd, uptr *pn));
+static INT get_string PROTO((INT fd, char *s, iptr max, INT *c));
 static IBOOL find_boot PROTO((const char *name, const char *ext, int fd, IBOOL errorp));
 static void load PROTO((ptr tc, iptr n, IBOOL base));
 static void check_boot_file_state PROTO((const char *who));
@@ -579,12 +582,7 @@ static IBOOL find_boot(name, ext, fd, errorp) const char *name, *ext; int fd; IB
   uptr n = 0;
   INT c;
   const char *path;
-#ifdef WIN32
-  wchar_t *expandedpath;
-#else
   char *expandedpath;
-#endif
-  glzFile file;
 
   if ((fd != -1) || S_fixedpathp(name)) {
     if (strlen(name) >= PATH_MAX) {
@@ -594,22 +592,13 @@ static IBOOL find_boot(name, ext, fd, errorp) const char *name, *ext; int fd; IB
 
     path = name;
 
-    if (fd != -1) {
-      file = S_glzdopen_input(fd);
-    } else {
-#ifdef WIN32
-      expandedpath = S_malloc_wide_pathname(path);
-      file = S_glzopen_input_w(expandedpath);
-#else
+    if (fd == -1) {
       expandedpath = S_malloc_pathname(path);
-      file = S_glzopen_input(expandedpath);
-#endif
-      /* assumption (seemingly true based on a glance at the source code):
-         S_glzopen_input doesn't squirrel away a pointer to expandedpath. */
+      fd = OPEN(expandedpath, O_BINARY|O_RDONLY, 0);
       free(expandedpath);
     }
 
-    if (!file) {
+    if (fd == -1) {
       if (errorp) {
         fprintf(stderr, "cannot open boot file %s\n", path);
         S_abnormal_exit();
@@ -621,22 +610,22 @@ static IBOOL find_boot(name, ext, fd, errorp) const char *name, *ext; int fd; IB
     if (verbose) fprintf(stderr, "trying %s...opened\n", path);
 
    /* check for magic number */
-    if (S_glzgetc(file) != fasl_type_header ||
-        S_glzgetc(file) != 0 ||
-        S_glzgetc(file) != 0 ||
-        S_glzgetc(file) != 0 ||
-        S_glzgetc(file) != 'c' ||
-        S_glzgetc(file) != 'h' ||
-        S_glzgetc(file) != 'e' ||
-        S_glzgetc(file) != 'z') {
+    if (get_u8(fd) != fasl_type_header ||
+        get_u8(fd) != 0 ||
+        get_u8(fd) != 0 ||
+        get_u8(fd) != 0 ||
+        get_u8(fd) != 'c' ||
+        get_u8(fd) != 'h' ||
+        get_u8(fd) != 'e' ||
+        get_u8(fd) != 'z') {
       fprintf(stderr, "malformed fasl-object header in %s\n", path);
       S_abnormal_exit();
     }
 
    /* check version */
-    if (zget_uptr(file, &n) != 0) {
+    if (get_uptr(fd, &n) != 0) {
       fprintf(stderr, "unexpected end of file on %s\n", path);
-      S_glzclose(file);
+      CLOSE(fd);
       S_abnormal_exit();
     }
 
@@ -644,21 +633,21 @@ static IBOOL find_boot(name, ext, fd, errorp) const char *name, *ext; int fd; IB
       fprintf(stderr, "%s is for Version %s; ", path, S_format_scheme_version(n));
      /* use separate fprintf since S_format_scheme_version returns static string */
       fprintf(stderr, "need Version %s\n", S_format_scheme_version(scheme_version));
-      S_glzclose(file);
+      CLOSE(fd);
       S_abnormal_exit();
     }
 
    /* check machine type */
-    if (zget_uptr(file, &n) != 0) {
+    if (get_uptr(fd, &n) != 0) {
       fprintf(stderr, "unexpected end of file on %s\n", path);
-      S_glzclose(file);
+      CLOSE(fd);
       S_abnormal_exit();
     }
 
     if (n != machine_type) {
       fprintf(stderr, "%s is for machine-type %s; need machine-type %s\n", path,
               S_lookup_machine_type(n), S_lookup_machine_type(machine_type));
-      S_glzclose(file);
+      CLOSE(fd);
       S_abnormal_exit();
     }
   } else {
@@ -679,17 +668,10 @@ static IBOOL find_boot(name, ext, fd, errorp) const char *name, *ext; int fd; IB
         }
       }
 
-#ifdef WIN32
-      expandedpath = S_malloc_wide_pathname(path);
-      file = S_glzopen_input_w(expandedpath);
-#else
       expandedpath = S_malloc_pathname(path);
-      file = S_glzopen_input(expandedpath);
-#endif
-      /* assumption (seemingly true based on a glance at the source code):
-         S_glzopen_input doesn't squirrel away a pointer to expandedpath. */
+      fd = OPEN(expandedpath, O_BINARY|O_RDONLY, 0);
       free(expandedpath);
-      if (!file) {
+      if (fd == -1) {
         if (verbose) fprintf(stderr, "trying %s...cannot open\n", path);
         continue;
       }
@@ -697,23 +679,23 @@ static IBOOL find_boot(name, ext, fd, errorp) const char *name, *ext; int fd; IB
       if (verbose) fprintf(stderr, "trying %s...opened\n", path);
 
      /* check for magic number */
-      if (S_glzgetc(file) != fasl_type_header ||
-          S_glzgetc(file) != 0 ||
-          S_glzgetc(file) != 0 ||
-          S_glzgetc(file) != 0 ||
-          S_glzgetc(file) != 'c' ||
-          S_glzgetc(file) != 'h' ||
-          S_glzgetc(file) != 'e' ||
-          S_glzgetc(file) != 'z') {
+      if (get_u8(fd) != fasl_type_header ||
+          get_u8(fd) != 0 ||
+          get_u8(fd) != 0 ||
+          get_u8(fd) != 0 ||
+          get_u8(fd) != 'c' ||
+          get_u8(fd) != 'h' ||
+          get_u8(fd) != 'e' ||
+          get_u8(fd) != 'z') {
         if (verbose) fprintf(stderr, "malformed fasl-object header in %s\n", path);
-        S_glzclose(file);
+        CLOSE(fd);
         continue;
       }
 
      /* check version */
-      if (zget_uptr(file, &n) != 0) {
+      if (get_uptr(fd, &n) != 0) {
         if (verbose) fprintf(stderr, "unexpected end of file on %s\n", path);
-        S_glzclose(file);
+        CLOSE(fd);
         continue;
       }
 
@@ -723,14 +705,14 @@ static IBOOL find_boot(name, ext, fd, errorp) const char *name, *ext; int fd; IB
          /* use separate fprintf since S_format_scheme_version returns static string */
           fprintf(stderr, "need Version %s\n", S_format_scheme_version(scheme_version));
         }
-        S_glzclose(file);
+        CLOSE(fd);
         continue;
       }
 
      /* check machine type */
-      if (zget_uptr(file, &n) != 0) {
+      if (get_uptr(fd, &n) != 0) {
         if (verbose) fprintf(stderr, "unexpected end of file on %s\n", path);
-        S_glzclose(file);
+        CLOSE(fd);
         continue;
       }
 
@@ -738,7 +720,7 @@ static IBOOL find_boot(name, ext, fd, errorp) const char *name, *ext; int fd; IB
         if (verbose)
           fprintf(stderr, "%s is for machine-type %s; need machine-type %s\n", path,
                   S_lookup_machine_type(n), S_lookup_machine_type(machine_type));
-        S_glzclose(file);
+        CLOSE(fd);
         continue;
       }
 
@@ -748,58 +730,61 @@ static IBOOL find_boot(name, ext, fd, errorp) const char *name, *ext; int fd; IB
 
   if (verbose) fprintf(stderr, "version and machine type check\n");
 
-  if (S_glzgetc(file) != '(') {  /* ) */
+  if (get_u8(fd) != '(') {  /* ) */
     fprintf(stderr, "malformed boot file %s\n", path);
-    S_glzclose(file);
+    CLOSE(fd);
     S_abnormal_exit();
   }
 
   /* ( */
-  if ((c = S_glzgetc(file)) == ')') {
+  if ((c = get_u8(fd)) == ')') {
     if (boot_count != 0) {
       fprintf(stderr, "base boot file %s must come before other boot files\n", path);
-      S_glzclose(file);
+      CLOSE(fd);
       S_abnormal_exit();
     }
   } else {
     if (boot_count == 0) {
       for (;;) {
-        S_glzungetc(c, file);
        /* try to load heap or boot file this boot file requires */
-        if (zgetstr(file, buf, PATH_MAX) != 0) {
+        if (get_string(fd, buf, PATH_MAX, &c) != 0) {
           fprintf(stderr, "unexpected end of file on %s\n", path);
-          S_glzclose(file);
+          CLOSE(fd);
           S_abnormal_exit();
         }
         if (find_boot(buf, ".boot", -1, 0)) break;
-        if ((c = S_glzgetc(file)) == ')') {
+        if (c == ')') {
           char *sep; char *wastebuf[8];
-          fprintf(stderr, "cannot find subordinate boot file ");
-          S_glzrewind(file);
-          (void) S_glzread(file, wastebuf, 8); /* magic number */
-          (void) zget_uptr(file, &n); /* version */
-          (void) zget_uptr(file, &n); /* machine type */
-          (void) S_glzgetc(file);        /* open paren */
-          for (sep = ""; ; sep = "or ") {
-            if ((c = S_glzgetc(file)) == ')') break;
-            S_glzungetc(c, file);
-            (void) zgetstr(file, buf, PATH_MAX);
+          fprintf(stderr, "cannot find subordinate boot file");
+          if (LSEEK(fd, 0, SEEK_SET) != 0 || READ(fd, wastebuf, 8) != 8) { /* attempt to rewind and read magic number */
+            fprintf(stderr, "---retry with verbose flag for more information\n");
+            CLOSE(fd);
+            S_abnormal_exit();
+          }
+          (void) get_uptr(fd, &n); /* version */
+          (void) get_uptr(fd, &n); /* machine type */
+          (void) get_u8(fd);        /* open paren */
+          c = get_u8(fd);
+          for (sep = " "; ; sep = "or ") {
+            if (c == ')') break;
+            (void) get_string(fd, buf, PATH_MAX, &c);
             fprintf(stderr, "%s%s.boot ", sep, buf);
           }
           fprintf(stderr, "required by %s\n", path);
-          S_glzclose(file);
+          CLOSE(fd);
           S_abnormal_exit();
         }
       }
     }
 
    /* skip to end of header */
-    while ((c = S_glzgetc(file)) != ')') {
+    while (c != ')') {
       if (c < 0) {
         fprintf(stderr, "malformed boot file %s\n", path);
-        S_glzclose(file);
+        CLOSE(fd);
         S_abnormal_exit();
       }
+      c = get_u8(fd);
     }
   }
 
@@ -808,21 +793,27 @@ static IBOOL find_boot(name, ext, fd, errorp) const char *name, *ext; int fd; IB
     S_abnormal_exit();
   }
 
-  bd[boot_count].file = file;
+  bd[boot_count].fd = fd;
   strcpy(bd[boot_count].path, path);
   boot_count += 1;
 
   return 1;
 }
 
-static uptr zget_uptr(glzFile file, uptr *pn) {
+static octet get_u8(INT fd) {
+  octet buf[1];
+  if (READ(fd, &buf, 1) != 1) return -1;
+  return buf[0];
+}
+
+static uptr get_uptr(INT fd, uptr *pn) {
   uptr n, m; int c; octet k;
 
-  if ((c = S_glzgetc(file)) < 0) return -1;
+  if ((c = get_u8(fd)) < 0) return -1;
   k = (octet)c;
   n = k & 0x7F;
   while (k & 128) {
-    if ((c = S_glzgetc(file)) < 0) return -1;
+    if ((c = get_u8(fd)) < 0) return -1;
     k = (octet)c;
     m = n << 7;
     if (m >> 7 != n) return -1;
@@ -832,19 +823,17 @@ static uptr zget_uptr(glzFile file, uptr *pn) {
   return 0;
 }
 
-static INT zgetstr(file, s, max) glzFile file; char *s; iptr max; {
-  ICHAR c;
-
+static INT get_string(fd, s, max, c) INT fd; char *s; iptr max; INT *c; {
   while (max-- > 0) {
-    if ((c = S_glzgetc(file)) < 0) return -1;
-    if (c == ' ' || c == ')') {
-      if (c == ')') S_glzungetc(c, file);
+    if (*c < 0) return -1;
+    if (*c == ' ' || *c == ')') {
+      if (*c == ' ') *c = get_u8(fd);
       *s = 0;
       return 0;
     }
-    *s++ = c;
+    *s++ = *c;
+    *c = get_u8(fd);
   }
-
   return -1;
 }
 
@@ -861,53 +850,52 @@ static int set_load_binary(iptr n) {
   return 0;
 }
 
+static void boot_element(ptr tc, ptr x, iptr n) {
+  if (Sprocedurep(x)) {
+    S_initframe(tc, 0);
+    x = boot_call(tc, x, 0);
+  } else if (Sprocedurep(S_G.load_binary) || set_load_binary(n)) {
+    S_initframe(tc, 1);
+    S_put_arg(tc, 1, x);
+    x = boot_call(tc, S_G.load_binary, 1);
+  } else if (Svectorp(x)) {
+    /* sequence combination by vfasl, where vectors are not nested */
+    iptr i;
+    for (i = 0; i < Svector_length(x); i++)
+      boot_element(tc, Svector_ref(x, i), n);
+  }
+}
+
 static void load(tc, n, base) ptr tc; iptr n; IBOOL base; {
   ptr x; iptr i;
 
   if (base) {
-    S_G.error_invoke_code_object = S_boot_read(bd[n].file, bd[n].path);
+    S_G.error_invoke_code_object = S_boot_read(bd[n].fd, bd[n].path);
     if (!Scodep(S_G.error_invoke_code_object)) {
       (void) fprintf(stderr, "first object on boot file not code object\n");
       S_abnormal_exit();
     }
 
-    S_G.invoke_code_object = S_boot_read(bd[n].file, bd[n].path);
+    S_G.invoke_code_object = S_boot_read(bd[n].fd, bd[n].path);
     if (!Scodep(S_G.invoke_code_object)) {
       (void) fprintf(stderr, "second object on boot file not code object\n");
       S_abnormal_exit();
     }
-    S_G.base_rtd = S_boot_read(bd[n].file, bd[n].path);
+    S_G.base_rtd = S_boot_read(bd[n].fd, bd[n].path);
     if (!Srecordp(S_G.base_rtd)) {
       S_abnormal_exit();
     }
   }
 
   i = 0;
-  while (i++ < LOADSKIP && S_boot_read(bd[n].file, bd[n].path) != Seof_object);
+  while (i++ < LOADSKIP && S_boot_read(bd[n].fd, bd[n].path) != Seof_object);
 
-  while ((x = S_boot_read(bd[n].file, bd[n].path)) != Seof_object) {
+  while ((x = S_boot_read(bd[n].fd, bd[n].path)) != Seof_object) {
     if (loadecho) {
       printf("%ld: ", (long)i);
       fflush(stdout);
     }
-    if (Sprocedurep(x)) {
-      S_initframe(tc, 0);
-      x = boot_call(tc, x, 0);
-    } else if (Sprocedurep(S_G.load_binary) || set_load_binary(n)) {
-      S_initframe(tc, 1);
-      S_put_arg(tc, 1, x);
-      x = boot_call(tc, S_G.load_binary, 1);
-    } else if (Svectorp(x)) {
-      iptr j, n;
-      n = Svector_length(x);
-      for (j = 0; j < n; j += 1) {
-        ptr y = Svector_ref(x, j);
-        if (Sprocedurep(y)) {
-          S_initframe(tc, 0);
-          INITVECTIT(x, j) = boot_call(tc, y, 0);
-        }
-      }
-    }
+    boot_element(tc, x, n);
     if (loadecho) {
       S_prin1(x);
       putchar('\n');
@@ -917,7 +905,7 @@ static void load(tc, n, base) ptr tc; iptr n; IBOOL base; {
   }
 
   S_G.load_binary = Sfalse;
-  S_glzclose(bd[n].file);
+  CLOSE(bd[n].fd);
 }
 
 /***************************************************************************/
@@ -1113,7 +1101,7 @@ extern void Sbuild_heap(kernel, custom_init) const char *kernel; void (*custom_i
     }
   }
 
-  S_vfasl_boot_mode = -1; /* to static generation after compacting initial */
+  S_vfasl_boot_mode = 1; /* to static generation after compacting */
 
   if (boot_count != 0) {
     INT i = 0;
diff --git a/c/schsig.c b/c/schsig.c
index 64dff190a4..d5a92061c2 100644
--- a/c/schsig.c
+++ b/c/schsig.c
@@ -591,7 +591,7 @@ static void forward_signal_to_scheme PROTO((INT sig));
     sigprocmask(SIG_UNBLOCK,&set,(sigset_t *)0);\
 }
 
-/* we buffer up to SIGNALQUEUESIZE - 1 unhandled signals, the start dropping them. */
+/* we buffer up to SIGNALQUEUESIZE - 1 unhandled signals, then start dropping them. */
 #define SIGNALQUEUESIZE 64
 static IBOOL scheme_signals_registered;
 
diff --git a/c/thread.c b/c/thread.c
index ffe0ac9336..ffd6ca1b55 100644
--- a/c/thread.c
+++ b/c/thread.c
@@ -108,6 +108,8 @@ ptr S_create_thread_object(who, p_tc) const char *who; ptr p_tc; {
     VIRTREG(tc, i) = FIX(0);
   }
 
+  DSTBV(tc) = SRCBV(tc) = Sfalse;
+
  /* S_thread had better not do thread-local allocation */
   thread = S_thread(tc);
 
diff --git a/c/vfasl.c b/c/vfasl.c
index 70e1cd9c15..010aa7e98c 100644
--- a/c/vfasl.c
+++ b/c/vfasl.c
@@ -416,9 +416,9 @@ ptr S_vfasl(ptr bv, void *stream, iptr offset, iptr input_len)
           /* The symbol was already interned, so point to the existing one */
           INITSYMVAL(sym) = isym;
           if (S_vfasl_boot_mode > 0) {
-            IGEN gen = SegInfo(addr_get_segment(isym))->generation;
+            IGEN gen = SegInfo(ptr_get_segment(isym))->generation;
             if (gen < static_generation) {
-              printf("new %d!\n", gen);
+              printf("WARNING: vfasl symbol already interned, but at generation %d: %p ", gen, isym);
               S_prin1(isym);
               printf("\n");
             }
diff --git a/csug/intro.stex b/csug/intro.stex
index dc921120f2..7f0e1b22cb 100644
--- a/csug/intro.stex
+++ b/csug/intro.stex
@@ -97,7 +97,8 @@ Daniel, George Davidson, Matthew Flatt, Aziz Ghuloum, Bob Hieb, Andy Keep, and O
 contributed substantially to the development of {\ChezScheme}.
 {\ChezScheme}'s expression editor is based on a command-line editor for
 Scheme developed from 1989 through 1994 by C.~David Boyer.
-File compression is performed with the use of the zlib compression library
+File compression is performed with the use of the lz4 compression
+library developed by Yann Collet or the zlib compression library
 developed by Jean-loup Gailly and Mark Adler.
 Implementations of the list and vector sorting routines are based on
 Olin Shiver's opportunistic merge-sort algorithm and implementation.
diff --git a/csug/io.stex b/csug/io.stex
index db638736db..4678fab109 100644
--- a/csug/io.stex
+++ b/csug/io.stex
@@ -3390,6 +3390,15 @@ An exception is raised with condition-type \scheme{&assertion} if
 \var{obj} or any portion of \var{obj} has no external fasl representation,
 e.g., if \var{obj} is or contains a procedure.
 
+The fasl representation of \var{obj} is compressed if the parameter
+\scheme{fasl-compressed}, described below, is set to \scheme{#t},
+its default value.
+For this reason, \var{binary-output-port} generally should not be opened
+with the compressed option.
+A warning is issued (an exception with condition type \scheme{&warning}
+is raised) on the first attempt to write fasl objects to or read
+fasl objects from a compressed file.
+
 \schemedisplay
 (define bop (open-file-output-port "tmp.fsl"))
 (fasl-write '(a b c) bop)
@@ -3430,6 +3439,14 @@ corresponding to source code within an \scheme{eval-when} form with
 situation \scheme{load} or situations \scheme{visit} and \scheme{revisit})
 are never skipped.
 
+\scheme{fasl-read} automatically decompresses the representation
+of each fasl object written in compressed format by \scheme{fasl-write}.
+Thus, \var{binary-input-port} generally should not be opened with
+the compressed option.
+A warning is issued (an exception with condition type \scheme{&warning}
+is raised) on the first attempt to write fasl objects to or read
+fasl objects from a compressed file.
+
 \schemedisplay
 (define bop (open-file-output-port "tmp.fsl"))
 (fasl-write '(a b c) bop)
@@ -3441,6 +3458,23 @@ are never skipped.
 (close-port bip)
 \endschemedisplay
 
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{fasl-compressed}{\categorythreadparameter}{fasl-compressed}
+\listlibraries
+\endentryheader
+
+\noindent
+When this parameter is set to its default value, \scheme{#t},
+\scheme{fasl-write} compresses the representation of each object
+as it writes it, often resulting in substantially smaller output
+but possibly taking more time to write and read.
+The compression format and level are determined by the
+\index{\scheme{compress-format}}\scheme{compress-format}
+and
+\index{\scheme{compress-level}}\scheme{compress-level}
+parameters.
+
 
 %----------------------------------------------------------------------------
 \entryheader
diff --git a/csug/system.stex b/csug/system.stex
index bfd3c80a55..03fac9ee9b 100644
--- a/csug/system.stex
+++ b/csug/system.stex
@@ -1251,11 +1251,6 @@ to 3 just while the remainder of file is compiled.
 \scheme{compile-script} is like \scheme{compile-file} but differs in
 that it copies the leading \scheme{#!} line from the
 source-file script into the object file.
-When the \scheme{#!} line is present it is uncompressed in the output
-file even when the parameter
-\index{\scheme{compile-compressed}}\scheme{compile-compressed} is
-set to \scheme{#t}, causing the remainder of the file to be compressed.
-This allows it to be interpreted properly by the operating system.
 
 \scheme{compile-script} permits compiled script files to be created from
 source script to reduce script load time.
@@ -1518,9 +1513,6 @@ If \var{covop} is supplied, \scheme{compile-port} sends coverage information to
 The ports are closed automatically after compilation under the assumption
 the program that opens the ports and invokes \scheme{compile-port}
 will take care of closing the ports.
-Output will be compressed only if an output port is already set up to be
-compressed, e.g., if it was opened with the \scheme{compressed}
-file option.
 
 %----------------------------------------------------------------------------
 \entryheader
@@ -1556,9 +1548,6 @@ If \var{covop} is present, \var{compile-to-port} sends coverage information to
 The ports are not closed automatically after compilation under the assumption
 the program that opens the port and invokes \scheme{compile-to-port}
 will take care of closing the port.
-Output will be compressed only if an output port is already set up to be
-compressed, e.g., if it was opened with the \scheme{compressed}
-file option.
 
 When \var{obj-list} contains a single list-structured element whose
 first-element is the symbol \scheme{top-level-program},
@@ -2781,25 +2770,6 @@ name by replacing the object-file extension (normally \scheme{.so})
 with \scheme{.wpo}, or adding the extension \scheme{.wpo} if the
 object filename has no extension or has the extension \scheme{.wpo}.
 
-%----------------------------------------------------------------------------
-\entryheader
-\formdef{compile-compressed}{\categorythreadparameter}{compile-compressed}
-\listlibraries
-\endentryheader
-
-\noindent
-When this parameter is \scheme{#t}, the default, \scheme{compile-file},
-\scheme{compile-library}, \scheme{compile-script},
-\scheme{compile-program}, \scheme{compile-to-file},
-\scheme{compile-whole-program}, and \scheme{strip-fasl-file} compress
-the object files they create.
-The compression format and level are determined by the
-\index{\scheme{compress-format}}\scheme{compress-format}
-and
-\index{\scheme{compress-level}}\scheme{compress-level}
-parameters.
-
-
 %----------------------------------------------------------------------------
 \entryheader
 \formdef{compile-file-message}{\categorythreadparameter}{compile-file-message}
@@ -3397,10 +3367,9 @@ set of tests.
 One covin file is created for each object file, with the object-file
 extension replaced by the extension \scheme{.covin}.
 Each covin file contains the printed representation of a source table
-(Section~\ref{SECTSYNTAXSOURCETABLES}), compressed when the parameter
-\scheme{compile-compressed} is true, mapping each profiled source
-expression found during the compilation of the corresponding source
-file to a count of zero.
+(Section~\ref{SECTSYNTAXSOURCETABLES}), compressed using the compression
+format and level specified by \scheme{compress-format} and
+\scheme{compress-level}.
 This information can be read via
 \index{\scheme{get-source-table!}}\scheme{get-source-table!} and used
 as a universe of source expressions to identify source expressions
diff --git a/csug/use.stex b/csug/use.stex
index 521f96ab4d..fe8a9a54f9 100644
--- a/csug/use.stex
+++ b/csug/use.stex
@@ -1011,11 +1011,9 @@ command.
 \endschemedisplay
 
 Scripts may be compiled using \index{\scheme{compile-script}}\scheme{compile-script}, which is like
-\scheme{compile-file} but differs in two ways:
-(1) it copies the leading \scheme{#!} line from the source-file script
-into the object file, and (2) when the \scheme{#!} line is present,
-it disables the default compression of the resulting file, which would
-otherwise prevent it from being recognized as a script file.
+\scheme{compile-file} but differs in that it
+copies the leading \scheme{#!} line from the source-file script
+into the object file.
 
 If {\PetiteChezScheme} is installed, but not {\ChezScheme},
 \scheme{/usr/bin/scheme} may be
diff --git a/makefiles/Mf-install.in b/makefiles/Mf-install.in
index 71bb66cee5..9f4ffc6b98 100644
--- a/makefiles/Mf-install.in
+++ b/makefiles/Mf-install.in
@@ -62,7 +62,7 @@ InstallLZ4Target=
 #                 no changes should be needed below this point                #
 ###############################################################################
 
-Version=csv9.5.3.32
+Version=csv9.5.3.33
 Include=boot/$m
 PetiteBoot=boot/$m/petite.boot
 SchemeBoot=boot/$m/scheme.boot
diff --git a/mats/6.ms b/mats/6.ms
index 345a265a37..0db61d95ac 100644
--- a/mats/6.ms
+++ b/mats/6.ms
@@ -887,6 +887,26 @@
  )
 
 (mat fasl
+  (error?
+    (separate-eval '(let ([op (open-file-output-port "testfile.ss" (file-options compressed replace))])
+                      (fasl-write 3 op))))
+  (error?
+    (separate-eval '(let ([ip (open-file-input-port "testfile.ss" (file-options compressed))])
+                      (fasl-read ip))))
+  (equal?
+    (separate-eval '(with-exception-handler
+                      (lambda (c) (unless (warning? c) (raise-continuable c)))
+                      (lambda ()
+                        (let ([op (open-file-output-port "testfile.ss" (file-options compressed replace))])
+                          (fasl-write 3 op)))))
+    "")
+  (equal?
+    (separate-eval `(with-exception-handler
+                      (lambda (c) (unless (warning? c) (raise-continuable c)))
+                      (lambda ()
+                        (let ([ip (open-file-input-port "testfile.ss" (file-options compressed))])
+                          (fasl-read ip)))))
+    "3\n")
   (pretty-equal?
     (begin
       (call-with-port
@@ -926,10 +946,10 @@
           (open-file-input-port "testfile.ss")
           (get-stuff fasl-read))
         (call-with-port
-          (open-file-input-port "testfile.ss" (file-options compressed))
+          (open-file-input-port "testfile.ss" (file-options #;compressed))
           (get-stuff fasl-read))
         (call-with-port
-          (open-file-input-port "testfile.ss" (file-options compressed))
+          (open-file-input-port "testfile.ss" (file-options #;compressed))
           (get-stuff (lambda (p)
                        (when (eof-object? (lookahead-u8 p)) (printf "done\n"))
                        (fasl-read p))))
diff --git a/mats/7.ms b/mats/7.ms
index b5dfb909cb..4ff2686c9f 100644
--- a/mats/7.ms
+++ b/mats/7.ms
@@ -47,7 +47,7 @@
      (set! aaaaa 0)
      (load "testfile.so")
      (eqv? aaaaa 7))
-   (parameterize ([compile-compressed #f])
+   (parameterize ([fasl-compressed #f])
      (printf "***** expect \"compile-file\" message:~%")
      (compile-file "testfile")
      (set! aaaaa 0)
@@ -62,7 +62,7 @@
      (load "testfile.so")
      (eqv? aaaaa -7))
    (let ((ip (open-input-string "(let ((x -3) (y -4)) (set! aaaaa (+ x y)))"))
-         (op (open-file-output-port "testfile.so" (file-options replace compressed))))
+         (op (open-file-output-port "testfile.so" (file-options replace #;compressed))))
      (compile-port ip op)
      (close-input-port ip)
      (close-port op)
@@ -98,7 +98,7 @@
       'replace)
     #t)
   (equal?
-    (call-with-port (open-file-output-port "testfile.so" (file-options replace compressed))
+    (call-with-port (open-file-output-port "testfile.so" (file-options replace #;compressed))
       (lambda (op)
         (parameterize ([compile-imported-libraries #t])
           (compile-to-port
@@ -861,19 +861,19 @@
       '(printf "qq => ~a\n" qq))
     (delete-file "testfile-mc-2a.so")
     (delete-file "testfile-mc-2.so")
-    (display-string (separate-compile '(lambda (x) (parameterize ([compile-file-message #f] [compile-imported-libraries #t] [compile-compressed #f]) (maybe-compile-program x))) 'mc-2))
+    (display-string (separate-compile '(lambda (x) (parameterize ([compile-file-message #f] [compile-imported-libraries #t] [fasl-compressed #f]) (maybe-compile-program x))) 'mc-2))
     #t)
   (begin
     (let ([p (open-file-input/output-port "testfile-mc-2a.so" (file-options no-create no-fail no-truncate))])
       (set-port-length! p 73)
       (close-port p))
-    (display-string (separate-compile '(lambda (x) (parameterize ([compile-file-message #f] [compile-imported-libraries #t] [compile-compressed #f] [import-notify #t]) (maybe-compile-program x))) 'mc-2))
+    (display-string (separate-compile '(lambda (x) (parameterize ([compile-file-message #f] [compile-imported-libraries #t] [fasl-compressed #f] [import-notify #t]) (maybe-compile-program x))) 'mc-2))
     #t)
   (begin
     (let ([p (open-file-input/output-port "testfile-mc-2.so" (file-options no-create no-fail no-truncate))])
       (set-port-length! p 87)
       (close-port p))
-    (display-string (separate-compile '(lambda (x) (parameterize ([compile-file-message #f] [compile-imported-libraries #t] [compile-compressed #f] [import-notify #t]) (maybe-compile-program x))) 'mc-2))
+    (display-string (separate-compile '(lambda (x) (parameterize ([compile-file-message #f] [compile-imported-libraries #t] [fasl-compressed #f] [import-notify #t]) (maybe-compile-program x))) 'mc-2))
     #t)
   ; make sure maybe-compile-file handles missing include files gracefully
   (begin
@@ -1174,10 +1174,10 @@
     (separate-compile
       `(lambda (x)
          (call-with-port
-           (open-file-output-port (format "~a.so" x) (file-options compressed replace))
+           (open-file-output-port (format "~a.so" x) (file-options #;compressed replace))
            (lambda (op)
              (call-with-port
-               (open-file-output-port (format "~a.host" x) (file-options compressed replace))
+               (open-file-output-port (format "~a.host" x) (file-options #;compressed replace))
                (lambda (hostop)
                  (compile-to-port
                    '((library (testfile-hop1)
@@ -5191,12 +5191,12 @@ evaluating module init
     (let ()
       (define fake-concatenate-object-files
         (lambda (outfn infn . infn*)
-          (call-with-port (open-file-output-port outfn (file-options compressed replace))
+          (call-with-port (open-file-output-port outfn (file-options #;compressed replace))
             (lambda (op)
               (for-each
                 (lambda (infn)
                   (put-bytevector op
-                    (call-with-port (open-file-input-port infn (file-options compressed)) get-bytevector-all)))
+                    (call-with-port (open-file-input-port infn (file-options #;compressed)) get-bytevector-all)))
                 (cons infn infn*))))))
       (fake-concatenate-object-files "testfile-cof1fooP.so" "testfile-cof1foo.so" "testfile-cof1P.so")
       (fake-concatenate-object-files "testfile-cof1barB.so" "testfile-cof1bar.so" "testfile-cof1B.so"))
diff --git a/mats/Mf-a6nt b/mats/Mf-a6nt
index 74ca208c14..7e532a76e9 100644
--- a/mats/Mf-a6nt
+++ b/mats/Mf-a6nt
@@ -21,6 +21,8 @@ mdclean = cat_flush.exe cat_flush.obj foreign1.exp foreign1.lib foreign1.obj for
 
 include Mf-base
 
+export MSYS_NO_PATHCONV=1
+
 foreign1.so: $(fsrc)
 	cmd.exe /c "vs.bat amd64 && cl /DWIN32 /DX86_64 /Fe$@ /I${Include} /LD /MD /nologo ../bin/$m/csv953.lib $(fsrc)"
 
diff --git a/mats/Mf-i3nt b/mats/Mf-i3nt
index 3c8da577f1..c65675f948 100644
--- a/mats/Mf-i3nt
+++ b/mats/Mf-i3nt
@@ -21,6 +21,8 @@ mdclean = cat_flush.exe cat_flush.obj foreign1.exp foreign1.lib foreign1.obj for
 
 include Mf-base
 
+export MSYS_NO_PATHCONV=1
+
 foreign1.so: $(fsrc)
 	cmd.exe /c "vs.bat x86 && cl /DWIN32 /Fe$@ /I${Include} /LD /MD /nologo ../bin/$m/csv953.lib $(fsrc)"
 
diff --git a/mats/Mf-ta6nt b/mats/Mf-ta6nt
index 23f65694b0..f8b3e8197b 100644
--- a/mats/Mf-ta6nt
+++ b/mats/Mf-ta6nt
@@ -21,6 +21,8 @@ mdclean = cat_flush.exe cat_flush.obj foreign1.exp foreign1.lib foreign1.obj for
 
 include Mf-base
 
+export MSYS_NO_PATHCONV=1
+
 foreign1.so: $(fsrc)
 	cmd.exe /c "vs.bat amd64 && cl /DWIN32 /DX86_64 /Fe$@ /I${Include} /LD /MD /nologo ../bin/$m/csv953.lib $(fsrc)"
 
diff --git a/mats/Mf-ti3nt b/mats/Mf-ti3nt
index 3c7e300574..31d6a672de 100644
--- a/mats/Mf-ti3nt
+++ b/mats/Mf-ti3nt
@@ -21,6 +21,8 @@ mdclean = cat_flush.exe cat_flush.obj foreign1.exp foreign1.lib foreign1.obj for
 
 include Mf-base
 
+export MSYS_NO_PATHCONV=1
+
 foreign1.so: $(fsrc)
 	cmd.exe /c "vs.bat x86 && cl /DWIN32 /Fe$@ /I${Include} /LD /MD /nologo ../bin/$m/csv953.lib $(fsrc)"
 
diff --git a/mats/bytevector.ms b/mats/bytevector.ms
index a1305e53c2..00f100ab31 100644
--- a/mats/bytevector.ms
+++ b/mats/bytevector.ms
@@ -11286,8 +11286,11 @@
     (error? (bytevector-uncompress "hello"))
     (begin
       (define (round-trip-bytevector-compress bv)
-        (equal? (bytevector-uncompress (bytevector-compress bv))
-                bv))
+        (and
+          (equal? (let ([c-bv (#%$bytevector-compress bv 0)])
+                    (#%$bytevector-uncompress c-bv 0 (bytevector-length c-bv) (bytevector-length bv) 0))
+                  bv)
+          (equal? (bytevector-uncompress (bytevector-compress bv)) bv)))
       (round-trip-bytevector-compress (string->utf8 "hello")))
     (round-trip-bytevector-compress '#vu8())
     (round-trip-bytevector-compress (apply bytevector
@@ -11296,6 +11299,8 @@
                                                  '()
                                                  (cons (bitwise-and i 255)
                                                        (loop (+ i 1)))))))
+    (round-trip-bytevector-compress 
+      (call-with-port (open-file-input-port "prettytest.ss") get-bytevector-all))
     (error?
      ;; Need at least 8 bytes for result size
      (bytevector-uncompress '#vu8()))
diff --git a/mats/misc.ms b/mats/misc.ms
index fb6588bda6..65671fdefb 100644
--- a/mats/misc.ms
+++ b/mats/misc.ms
@@ -1784,6 +1784,9 @@
         (pretty-print '(pretty-print (not (((inspect/object sff-1a-x) 'code) 'source))))
         (pretty-print '(pretty-print (= (length (profile-dump)) preexisting-entries))))
       'replace)
+    (delete-file "testfile-sff-1a.so")
+    (delete-file "testfile-sff-1b.so")
+    (delete-file "testfile-sff-1c.so")
     (separate-compile
       '(lambda (x)
          (parameterize ([generate-inspector-information #t]
diff --git a/mats/root-experr-compile-0-f-f-f b/mats/root-experr-compile-0-f-f-f
index 9b3d5453b6..dd57ce0dec 100644
--- a/mats/root-experr-compile-0-f-f-f
+++ b/mats/root-experr-compile-0-f-f-f
@@ -4450,6 +4450,8 @@ cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<
 6.mo:Expected error in mat pretty-print: "incorrect argument count in call (pretty-format (quote foo) (quote x) (quote x))".
 6.mo:Expected error in mat pretty-print: "pretty-format: 3 is not a symbol".
 6.mo:Expected error in mat pretty-print: "pretty-format: invalid format (bad 0 ... ... 0 format)".
+6.mo:Expected error in mat fasl: "separate-eval: Warning in fasl-write: fasl file content is compressed internally; compressing the file (#<binary output port testfile.ss>) is redundant and can slow fasl writing and reading significantly
+6.mo:Expected error in mat fasl: "separate-eval: Warning in fasl-read: fasl file content is compressed internally; compressing the file (#<binary input port testfile.ss>) is redundant and can slow fasl writing and reading significantly
 6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "~a~~~s" in call to format".
 6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too many arguments for control string "~a~a~a~s" in call to format".
 6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "~a~~~s" in call to format at line 1, char 28 of testfile.ss".
diff --git a/mats/root-experr-compile-2-f-f-f b/mats/root-experr-compile-2-f-f-f
index b1008832dd..67c3f99152 100644
--- a/mats/root-experr-compile-2-f-f-f
+++ b/mats/root-experr-compile-2-f-f-f
@@ -4100,6 +4100,8 @@ cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<
 6.mo:Expected error in mat pretty-print: "incorrect argument count in call (pretty-format (quote foo) (quote x) (quote x))".
 6.mo:Expected error in mat pretty-print: "pretty-format: 3 is not a symbol".
 6.mo:Expected error in mat pretty-print: "pretty-format: invalid format (bad 0 ... ... 0 format)".
+6.mo:Expected error in mat fasl: "separate-eval: Warning in fasl-write: fasl file content is compressed internally; compressing the file (#<binary output port testfile.ss>) is redundant and can slow fasl writing and reading significantly
+6.mo:Expected error in mat fasl: "separate-eval: Warning in fasl-read: fasl file content is compressed internally; compressing the file (#<binary input port testfile.ss>) is redundant and can slow fasl writing and reading significantly
 6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "~a~~~s" in call to format".
 6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too many arguments for control string "~a~a~a~s" in call to format".
 6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "~a~~~s" in call to format at line 1, char 28 of testfile.ss".
diff --git a/mats/thread.ms b/mats/thread.ms
index 64d9e403d0..3dd289679c 100644
--- a/mats/thread.ms
+++ b/mats/thread.ms
@@ -129,7 +129,7 @@
       (lambda (start stop target)
         (let ([t (time-difference stop start)])
           (<= (abs (- (+ (time-second t) (* (time-nanosecond t) 1e-9)) target))
-              0.1))))
+              0.2))))
     (andmap procedure? (list $threads $fib $thread-check $time-in-range?)))
   ($thread-check)
   (not (= (let ([n #f])
diff --git a/release_notes/release_notes.stex b/release_notes/release_notes.stex
index ab75cc8774..e65c37cef0 100644
--- a/release_notes/release_notes.stex
+++ b/release_notes/release_notes.stex
@@ -112,6 +112,47 @@ unordered by default. An ordered guardian's objects are classified as
 inaccessible only when they are not reachable from the represetative
 of any inaccessible object in any other guardian.
 
+\subsection{Unicode Basic Multilingual Plane console I/O in Windows (9.5.3)}
+
+Console I/O now supports characters from the Unicode Basic
+Multilingual Plane in Windows. Windows consoles do not yet support the
+supplementary planes.
+
+\subsection{Incompatible fasl-format and compiled-file compression changes (9.5.3)}
+
+The fasl (fast-load) format now supports per-object compression.
+Whether the fasl writer actually performs compression is determined
+by the new \scheme{fasl-compressed} parameter, whose value defaults
+to \scheme{#t}.
+The compression format and level are determined by the
+\scheme{compress-format} and \scheme{compress-level}
+parameters.
+
+The \scheme{compile-compressed} parameter has been eliminated.
+Since compiled files are written in fasl format, the
+\scheme{fasl-compressed} parameter also now controls whether compiled
+files are compressed.
+
+Because individual portions of a fasl file are already compressed
+by default, attempting to compress a fasl file as a whole is often
+ineffective as well as inefficient both when writing and reading
+fasl objects.
+Thus, in particular, the \var{output-port} and \scheme{wpo-port}
+supplied to \scheme{compile-port} and \scheme{compile-to-port}
+should not be opened for compression.
+Similarly, external tools should not expect compiled files to be
+compressed as a whole, nor should they compress compiled files.
+
+Because compression of fasl files was previously encouraged and is
+now discouraged, the first attempt to write fasl data to or read
+fasl data from a compressed port will cause a warning to be issued,
+i.e., an exception with condition type \scheme{&warning} to be
+raised.
+
+The rationale for this change is to allow the fasl reader to seek
+past, without reading, portions of an object file that contain
+compile-time code at run time and run-time code at compile time.
+
 \subsection{Bytevector compression and compression level (9.5.3)}
 
 The procedure \scheme{bytevector-compress} now selects the level of
diff --git a/s/4.ss b/s/4.ss
index a23fb7dd38..bf0630740f 100644
--- a/s/4.ss
+++ b/s/4.ss
@@ -1,4 +1,3 @@
-"4.ss"
 ;;; 4.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,6 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 (define-who apply
   (let ()
     (define-syntax build-apply
@@ -55,12 +55,6 @@
                  cl ...))])))
     (build-apply (x1 x2 x3 x4))))
 
-(define ormap)
-(define andmap)
-(define map)
-(define for-each)
-(define fold-left)
-(define fold-right)
 (let ()
   (define length-error
      (lambda (who l1 l2)
@@ -440,3 +434,4 @@
       (unless (procedure? promise)
          ($oops who "~s is not a procedure" promise))
       (promise)))
+)
diff --git a/s/5_1.ss b/s/5_1.ss
index b0524ffad0..4315602fc2 100644
--- a/s/5_1.ss
+++ b/s/5_1.ss
@@ -1,4 +1,3 @@
-"5_1.ss"
 ;;; 5_1.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -16,6 +15,7 @@
 
 ;;; type and generic predicates
 
+(begin
 (define boolean?
    (lambda (x)
       (or (eq? x #t) (eq? x #f))))
@@ -364,3 +364,4 @@
             (or (null? s*)
                 (and (#3%symbol=? (car s*) s1)
                      (f (cdr s*))))))]))
+)
diff --git a/s/5_2.ss b/s/5_2.ss
index de579b19ea..35ff456a39 100644
--- a/s/5_2.ss
+++ b/s/5_2.ss
@@ -1,4 +1,3 @@
-"5_2.ss"
 ;;; 5_2.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -16,6 +15,7 @@
 
 ;;; list and pair functions
 
+(begin
 (define atom?
    (lambda (x)
       (not (pair? x))))
@@ -820,3 +820,5 @@
                              (loop (cdr fast) slow #t))]
                         [else
                          (return bits)]))])))))))
+
+)
diff --git a/s/5_3.ss b/s/5_3.ss
index b1e0aea996..af6ff11aec 100644
--- a/s/5_3.ss
+++ b/s/5_3.ss
@@ -1,4 +1,3 @@
-"5_3.ss"
 ;;; 5_3.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -24,6 +23,7 @@
 ;;; dangerous: -0.0, +inf.0, -inf.0, 1e100, 1e-100, 0.1
 ;;; safe: 0.0, +nan.0, 1.0, 2.0, 0.5
 
+(begin
 (eval-when (compile)
 
    (define-constant max-float-exponent
@@ -3281,3 +3281,4 @@
              [k (- end start) (- k w-1)])
             ((<= k w-1) (logor (sll m^ k) ($fxreverse m k))))))))
 )))))))
+)
diff --git a/s/5_4.ss b/s/5_4.ss
index 9036c3de07..1580505440 100644
--- a/s/5_4.ss
+++ b/s/5_4.ss
@@ -1,4 +1,3 @@
-"5_4.ss"
 ;;; 5_4.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -16,6 +15,7 @@
 
 ;;; character and string functions
 
+(begin
 (define substring
    (lambda (s1 m n)
       (unless (string? s1)
@@ -849,3 +849,4 @@
         ($compose ($decompose s #f))))
   )
 )
+)
diff --git a/s/5_6.ss b/s/5_6.ss
index 0fd4f5c4ee..25bca39b35 100644
--- a/s/5_6.ss
+++ b/s/5_6.ss
@@ -1,4 +1,3 @@
-"5_6.ss"
 ;;; 5_6.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
diff --git a/s/5_7.ss b/s/5_7.ss
index 551fe9ac24..a2ffc8435e 100644
--- a/s/5_7.ss
+++ b/s/5_7.ss
@@ -1,4 +1,3 @@
-"5_7.ss"
 ;;; 5_7.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -16,6 +15,7 @@
 
 ;;; symbol functions
 
+(begin
 (define property-list
    (lambda (s)
       (unless (symbol? s)
@@ -79,14 +79,10 @@
                 (set-cdr! prev (cdr (cdr pl)))
                 ($set-system-property-list! s (cdr (cdr pl))))
             (rp (cdr (cdr pl)) (cdr pl)))))))
+)
 
 (eval-when (compile) (optimize-level 3))
 
-(define $gensym->pretty-name)
-(define gensym-prefix)
-(define gensym-count)
-(define gensym->unique-string)
-(define gensym)
 (let ([prefix "g"] [count 0])
   (define generate-unique-name
    ; a-z must come first in alphabet.  separator must not be in alphabet.
diff --git a/s/6.ss b/s/6.ss
index 14adf00cd5..3edcffd81c 100644
--- a/s/6.ss
+++ b/s/6.ss
@@ -1,4 +1,3 @@
-"6.ss"
 ;;; 6.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,6 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 (define with-output-to-string
   (lambda (th)
     (unless (procedure? th)
@@ -502,3 +502,4 @@
                 [else (loop (fx+ i 1))]))
             (substring s (skip-sep s base n) n)))))
 )
+)
diff --git a/s/7.ss b/s/7.ss
index 219280db65..c2f618ca88 100644
--- a/s/7.ss
+++ b/s/7.ss
@@ -1,4 +1,3 @@
-"7.ss"
 ;;; 7.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -16,6 +15,7 @@
 
 ;;; system operations
 
+(begin
 (define scheme-start
   (make-parameter
     (lambda fns (for-each load fns) (new-cafe))
@@ -125,9 +125,16 @@
                       (p path)
                       (loop (cdr ls))))))))))
 
+(set! $compressed-warning
+  (let ([warned? #f])
+    (lambda (who p)
+      (unless warned?
+        (set! warned? #t)
+        (warningf who "fasl file content is compressed internally; compressing the file (~s) is redundant and can slow fasl writing and reading significantly" p)))))
+
 (set-who! fasl-read
   (let ()
-    (define $fasl-read (foreign-procedure "(cs)fasl_read" (ptr boolean fixnum ptr) ptr))
+    (define $fasl-read (foreign-procedure "(cs)fasl_read" (int fixnum ptr) ptr))
     (define $bv-fasl-read (foreign-procedure "(cs)bv_fasl_read" (ptr int uptr uptr ptr) ptr))
     (define (get-uptr p)
       (let ([k (get-u8 p)])
@@ -136,12 +143,19 @@
               (let ([k (get-u8 p)])
                 (f k (logor (ash n 7) (fxand k #x7F))))
               n))))
-    (define (malformed p) ($oops who "malformed fasl-object header found in ~s" p))
+    (define (get-uptr/bytes p)
+      (let ([k (get-u8 p)])
+        (let f ([k k] [n (fxand k #x7F)] [bytes 1])
+          (if (fxlogbit? 7 k)
+              (let ([k (get-u8 p)])
+                (f k (logor (ash n 7) (fxand k #x7F)) (fx+ bytes 1)))
+              (values n bytes)))))
+    (define (malformed p what) ($oops who "malformed fasl-object found in ~s (~a)" p what))
     (define (check-header p)
       (let ([bv (make-bytevector 8 (constant fasl-type-header))])
         (unless (and (eqv? (get-bytevector-n! p bv 1 7) 7)
                      (bytevector=? bv (constant fasl-header)))
-          (malformed p)))
+          (malformed p "invalid header")))
       (let ([n (get-uptr p)])
         (unless (= n (constant scheme-version))
           ($oops who "incompatible fasl-object version ~a found in ~s"
@@ -153,21 +167,36 @@
              (lambda (a)
                ($oops who "incompatible fasl-object machine-type ~s found in ~s"
                  (cdr a) p))]
-            [else (malformed p)])))
+            [else (malformed p "unrecognized machine type")])))
       (unless (and (eqv? (get-u8 p) (char->integer #\()) ;)
                    (let f ()
                      (let ([n (get-u8 p)])
                        (and (not (eof-object? n)) ;(
                             (or (eqv? n (char->integer #\))) (f))))))
-        (malformed p)))
+        (malformed p "invalid list of base boot files")))
+    (define (call-with-bytevector-and-offset p len proc)
+      ;; fasl-read directly from the port buffer if it has `len`
+      ;; bytes ready, which works for a bytevector port; disable
+      ;; interrupt to make sure the bytes stay available (and
+      ;; `$bv-fasl-read` take tc-mutex, anyway)
+      ((with-interrupts-disabled
+        (let ([idx (binary-port-input-index p)])
+          (cond
+            [(<= len (fx- (binary-port-input-size p) idx))
+             (let ([result (proc (binary-port-input-buffer p) idx)])
+               (set-binary-port-input-index! p (fx+ idx len))
+               (lambda () result))]
+            [else
+             ;; Call `get-bytevector-n`, etc. with interrupts reenabled
+             (lambda ()
+               (proc (get-bytevector-n p len) 0))])))))
     (define (go p situation)
       (define (go1)
         (if (and ($port-flags-set? p (constant port-flag-file))
+                 (or (not ($port-flags-set? p (constant port-flag-compressed)))
+                     (begin ($compressed-warning who p) #f))
                  (eqv? (binary-port-input-count p) 0))
-            ($fasl-read ($port-info p)
-              ($port-flags-set? p (constant port-flag-compressed))
-              situation
-              (port-name p))
+            ($fasl-read ($port-info p) situation (port-name p))
             (let fasl-entry ()
               (let ([ty (get-u8 p)])
                 (cond
@@ -181,37 +210,36 @@
                    (go2 (eqv? situation (constant fasl-type-visit)))]
                   [(eqv? ty (constant fasl-type-visit-revisit))
                    (go2 #f)]
-                  [else (malformed p)])))))
+                  [else (malformed p "invalid situation")])))))
       (define (go2 skip?)
-        (let ([ty (get-u8 p)])
-          (cond
-            [(or (eqv? ty (constant fasl-type-fasl-size))
-                 (eqv? ty (constant fasl-type-vfasl-size)))
-             (let ([len (get-uptr p)])
-               (if skip?
-                   (begin
-                     (if (and (port-has-port-position? p) (port-has-set-port-position!? p))
-                         (set-port-position! p (+ (port-position p) len))
-                         (get-bytevector-n p len))
-                     (go1))
-                   (let ([name (port-name p)])
-                     ;; fasl-read directly from the port buffer if it has `len`
-                     ;; bytes ready, which works for a bytevector port; disable
-                     ;; interrupt to make sure the bytes stay available (and
-                     ;; `$bv-fasl-read` takes tc-mutex, anyway)
-                     ((with-interrupts-disabled
-                       (let ([idx (binary-port-input-index p)])
-                         (cond
-                          [(<= len (fx- (binary-port-input-size p) idx))
-                           (let ([result ($bv-fasl-read (binary-port-input-buffer p) ty
-                                                        idx len name)])
-                             (set-binary-port-input-index! p (+ idx len))
-                             (lambda () result))]
-                          [else
-                           ;; Call `get-bytevector-n`, etc. with interrupts reenabled
-                           (lambda ()
-                             ($bv-fasl-read (get-bytevector-n p len) ty 0 len name))])))))))]
-            [else (malformed p)])))
+        (let ([n (get-uptr p)])
+          (if skip?
+              (begin
+                (if (and (port-has-port-position? p) (port-has-set-port-position!? p))
+                    (set-port-position! p (+ (port-position p) n))
+                    (get-bytevector-n p n))
+                (go1))
+              (let* ([compressed-flag (get-u8 p)]
+                     [kind (get-u8 p)])
+                (cond
+                  [(or (eqv? compressed-flag (constant fasl-type-gzip)) (eqv? compressed-flag (constant fasl-type-lz4)))
+                   (let-values ([(dest-size dest-size-bytes) (get-uptr/bytes p)])
+                     (let* ([src-size (- n 2 dest-size-bytes)]
+                            [bv (call-with-bytevector-and-offset
+                                 p src-size
+                                 (lambda (bv offset)
+                                   ($bytevector-uncompress bv offset src-size dest-size
+                                      (if (eqv? compressed-flag (constant fasl-type-gzip))
+                                          (constant COMPRESS-GZIP)
+                                          (constant COMPRESS-LZ4)))))])
+                       ($bv-fasl-read bv kind 0 dest-size (port-name p))))]
+                  [(eqv? compressed-flag (constant fasl-type-uncompressed))
+                   (let ([len (- n 2)])
+                     (call-with-bytevector-and-offset
+                      p len
+                      (lambda (bv offset)
+                        ($bv-fasl-read bv kind offset len (port-name p)))))]
+                  [else (malformed p "invalid compression")])))))
       (unless (and (input-port? p) (binary-port? p))
         ($oops who "~s is not a binary input port" p))
       (go1))
@@ -270,7 +298,7 @@
          [(program-info? x) ($install-program-desc x)]
          [(recompile-info? x) (void)]
          [(Lexpand? x) ($interpret-backend x situation for-import? importer fn)]
-                                        ; NB: this is here to support the #t inserted by compile-file-help2 after header information
+         ; NB: this is here to support the #t inserted by compile-file-help2 after header information
          [(eq? x #t) (void)]
          ;; for vfasl combinations:
          [(vector? x) (run-vector x)]
@@ -293,15 +321,11 @@
                                       fp
                                       (loop fp))))))
                         (begin (set-port-position! ip start-pos) 0)))])
-          (port-file-compressed! ip)
           (if ($compiled-file-header? ip)
               (begin
                 (do-load-binary who fn ip situation for-import? importer)
                 (close-port ip))
               (begin
-                (when ($port-flags-set? ip (constant port-flag-compressed))
-                  (close-port ip)
-                  ($oops who "missing header for compiled file ~s" fn))
                 (unless ksrc
                   (close-port ip)
                   ($oops who "~a is not a compiled file" fn))
@@ -1563,3 +1587,4 @@
         [() (print-pass-stats #f ($pass-stats))]
         [(key) (print-pass-stats key ($pass-stats))]
         [(key psl*) (print-pass-stats key psl*)]))))
+)
diff --git a/s/Mf-base b/s/Mf-base
index 375fd02cf6..c8006135fb 100644
--- a/s/Mf-base
+++ b/s/Mf-base
@@ -33,8 +33,8 @@ i = f
 # cp0 determines the number of cp0 (source optimizer) iterations run
 cp0 = 2
 
-# cc determines whether compiled files are compressed
-cc = t
+# fc determines whether fasl objects are compressed
+fc = t
 
 # xf determines the compression foramt
 xf = (compress-format)
@@ -228,7 +228,7 @@ clean: profileclean
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(when #$p (compile-profile (quote source)))'\
@@ -257,7 +257,7 @@ clean: profileclean
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(when #$p (compile-profile (quote source)))'\
@@ -289,7 +289,7 @@ clean: profileclean
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(generate-inspector-information #$i)'\
@@ -302,7 +302,7 @@ clean: profileclean
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(when #$(xp) (compile-profile (quote source)))'\
@@ -378,7 +378,7 @@ cmacros.so: cmacros.ss machine.def layout.ss
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(generate-inspector-information #$i)'\
@@ -393,7 +393,7 @@ priminfo.so: priminfo.ss primdata.ss cmacros.so
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(generate-inspector-information #$i)'\
@@ -409,7 +409,7 @@ mkheader.so: mkheader.ss cmacros.so primvars.so env.so
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(generate-inspector-information #$i)'\
@@ -424,7 +424,7 @@ mkgc.so: mkgc.ss mkheader.so cmacros.so primvars.so env.so
              '(optimize-level 0)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(generate-inspector-information #$i)'\
@@ -439,7 +439,7 @@ nanopass.so: $(shell echo ../nanopass/nanopass/*) ../nanopass/nanopass.ss
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(generate-inspector-information #$i)'\
@@ -465,7 +465,7 @@ script.all makescript:
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(when #$p (compile-profile (quote source)))'\
@@ -508,7 +508,7 @@ script-static.all:
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(when #$p (compile-profile (quote source)))'\
@@ -537,7 +537,7 @@ script-dynamic.all:
              '(optimize-level $o)'\
              '(debug-level $d)'\
              '(commonization-level $(cl))'\
-             '(compile-compressed #$(cc))'\
+             '(fasl-compressed #$(fc))'\
              '(compress-format $(xf))'\
              '(compress-level $(xl))'\
              '(when #$p (compile-profile (quote source)))'\
diff --git a/s/back.ss b/s/back.ss
index 994d784d63..e7341caaf5 100644
--- a/s/back.ss
+++ b/s/back.ss
@@ -1,4 +1,3 @@
-"back.ss"
 ;;; back.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,6 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 (define-who trace-output-port
    ($make-thread-parameter
       (console-output-port)
@@ -155,7 +155,7 @@
         ($oops who "~s is not a procedure" x))
       x)))
 
-(define compile-compressed
+(define fasl-compressed
   ($make-thread-parameter #t (lambda (x) (and x #t))))
 
 (define compile-file-message
@@ -226,3 +226,4 @@
   ($make-thread-parameter #t (lambda (x) (and x #t))))
 
 (set! $scheme-version (string->symbol ($format-scheme-version (constant scheme-version))))
+)
diff --git a/s/bytevector.ss b/s/bytevector.ss
index be491650ed..026cbc386e 100644
--- a/s/bytevector.ss
+++ b/s/bytevector.ss
@@ -1,4 +1,3 @@
-"bytevector.ss"
 ;;; bytevector.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;;
@@ -1464,62 +1463,59 @@
     ;; Always big-endian, so that compressed data is portable.
     (define uncompressed-length-endianness (endianness big))
 
-    (define $bytevector-compress-size
+    (define fp-bytevector-compress-size
       (foreign-procedure "(cs)bytevector_compress_size" (iptr int) uptr))
-    (define $bytevector-compress
+    (define fp-bytevector-compress
       (foreign-procedure "(cs)bytevector_compress" (scheme-object iptr iptr scheme-object iptr iptr int) scheme-object))
-    (define $bytevector-uncompress
+    (define fp-bytevector-uncompress
       (foreign-procedure "(cs)bytevector_uncompress" (scheme-object iptr iptr scheme-object iptr iptr int) scheme-object))
 
-    (set-who! bytevector-compress
-      (lambda (bv)
-        (unless (bytevector? bv) (not-a-bytevector who bv))
-        (let* ([fmt ($tc-field 'compress-format ($tc))]
-               [dest-max-len ($bytevector-compress-size (bytevector-length bv) fmt)]
-               [dest-alloc-len (min (+ dest-max-len uncompressed-length-length)
-                                    ;; In the unlikely event of a non-fixnum requested size...
-                                    (constant maximum-bytevector-length))]
+    (let ()
+      (define (compress who bv fmt offset)
+        (let* ([dest-max-len (fp-bytevector-compress-size (bytevector-length bv) fmt)]
+               [dest-alloc-len (min (+ dest-max-len offset) (constant maximum-bytevector-length))]
                [dest-bv (make-bytevector dest-alloc-len)])
-          (let ([r ($bytevector-compress dest-bv
-                                         uncompressed-length-length
-                                         (fx- dest-alloc-len uncompressed-length-length)
-                                         bv
-                                         0
-                                         (bytevector-length bv)
-                                         fmt)])
-            (cond
-             [(string? r)
-              ($oops who r bv)]
-             [else
-              (let ([tag (bitwise-ior
-                           (bitwise-arithmetic-shift-left (bytevector-length bv) (constant COMPRESS-FORMAT-BITS))
-                           fmt)])
-                ($bytevector-u64-set! dest-bv 0 tag uncompressed-length-endianness who)
-                (bytevector-truncate! dest-bv (fx+ r uncompressed-length-length)))])))))
+          (let ([r (fp-bytevector-compress dest-bv offset (fx- dest-alloc-len offset) bv 0 (bytevector-length bv) fmt)])
+            (if (string? r)
+                ($oops who r bv)
+                (bytevector-truncate! dest-bv (fx+ r offset))))))
 
-    (set-who! bytevector-uncompress
-      (lambda (bv)
-        (unless (bytevector? bv) (not-a-bytevector who bv))
-        (unless (>= (bytevector-length bv) uncompressed-length-length)
-          ($oops who "invalid data in source bytevector ~s" bv))
-        (let* ([tag ($bytevector-u64-ref bv 0 uncompressed-length-endianness who)]
-               [fmt (logand tag (fx- (fxsll 1 (constant COMPRESS-FORMAT-BITS)) 1))]
-               [dest-length (bitwise-arithmetic-shift-right tag (constant COMPRESS-FORMAT-BITS))])
-          (unless (and (fixnum? dest-length)
-                       ($fxu< dest-length (constant maximum-bytevector-length)))
-            ($oops who "bytevector ~s claims invalid uncompressed size ~s" bv dest-length))
-          (let* ([dest-bv (make-bytevector dest-length)]
-                 [r ($bytevector-uncompress dest-bv
-                                            0
-                                            dest-length
-                                            bv
-                                            uncompressed-length-length
-                                            (fx- (bytevector-length bv) uncompressed-length-length)
-                                            fmt)])
-            (cond
-             [(string? r) ($oops who r bv)]
-             [(fx= r dest-length) dest-bv]
-             [else
-              ($oops who "uncompressed size ~s for ~s is smaller than expected size ~a" r bv dest-length)]))))))
+      (set-who! $bytevector-compress
+        (lambda (bv fmt)
+          (compress who bv fmt 0)))
 
+      (set-who! bytevector-compress
+        (lambda (bv)
+          (unless (bytevector? bv) (not-a-bytevector who bv))
+          (let* ([fmt ($tc-field 'compress-format ($tc))]
+                 [dest-bv (compress who bv fmt uncompressed-length-length)])
+            (let ([tag (bitwise-ior
+                         (bitwise-arithmetic-shift-left (bytevector-length bv) (constant COMPRESS-FORMAT-BITS))
+                         fmt)])
+              ($bytevector-u64-set! dest-bv 0 tag uncompressed-length-endianness who)
+              dest-bv)))))
+
+    (let ()
+      (define (uncompress who bv dest-length fmt offset src-length)
+        (unless (and (fixnum? dest-length) ($fxu< dest-length (constant maximum-bytevector-length)))
+          ($oops who "bytevector ~s claims invalid uncompressed size ~s" bv dest-length))
+        (let ([dest-bv (make-bytevector dest-length)])
+          (let ([r (fp-bytevector-uncompress dest-bv 0 dest-length bv offset src-length fmt)])
+            (cond
+              [(string? r) ($oops who r bv)]
+              [(fx= r dest-length) dest-bv]
+              [else ($oops who "uncompressed size ~s for ~s is smaller than expected size ~s" r bv dest-length)]))))
+
+      (set-who! $bytevector-uncompress
+        (lambda (bv offset len dest-length fmt)
+          (uncompress who bv dest-length fmt offset len)))
+
+      (set-who! bytevector-uncompress
+        (lambda (bv)
+          (unless (bytevector? bv) (not-a-bytevector who bv))
+          (unless (>= (bytevector-length bv) uncompressed-length-length) ($oops who "invalid data in source bytevector ~s" bv))
+          (let* ([tag ($bytevector-u64-ref bv 0 uncompressed-length-endianness who)]
+                 [fmt (logand tag (fx- (fxsll 1 (constant COMPRESS-FORMAT-BITS)) 1))]
+                 [dest-length (bitwise-arithmetic-shift-right tag (constant COMPRESS-FORMAT-BITS))])
+            (uncompress who bv dest-length fmt uncompressed-length-length (fx- (bytevector-length bv) uncompressed-length-length)))))))
 )
diff --git a/s/cafe.ss b/s/cafe.ss
index 720cfbd724..e5d2f242b3 100644
--- a/s/cafe.ss
+++ b/s/cafe.ss
@@ -1,4 +1,3 @@
-"cafe.ss"
 ;;; cafe.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,6 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 (define default-prompt-and-read
   (lambda (n)
     (unless (and (integer? n) (>= n 0))
@@ -214,3 +214,4 @@ Type e to exit interrupt handler and continue
                      (lambda ()
                        (waiter ($cafe) eval))))))))]))))
 )
+)
diff --git a/s/cback.ss b/s/cback.ss
index 7ba4544cdf..cedc90a9f9 100644
--- a/s/cback.ss
+++ b/s/cback.ss
@@ -1,4 +1,3 @@
-"cback.ss"
 ;;; cback.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,5 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 (current-eval compile)
 (define $compiler-is-loaded? #t)
+)
diff --git a/s/cmacros.ss b/s/cmacros.ss
index b720830810..ab43c68dd8 100644
--- a/s/cmacros.ss
+++ b/s/cmacros.ss
@@ -348,7 +348,7 @@
 ;; ---------------------------------------------------------------------
 ;; Version and machine types:
 
-(define-constant scheme-version #x09050320)
+(define-constant scheme-version #x09050321)
 
 (define-syntax define-machine-types
   (lambda (x)
@@ -470,8 +470,8 @@
 (define-constant fasl-type-graph-ref 18)
 (define-constant fasl-type-gensym 19)
 (define-constant fasl-type-exactnum 20)
-(define-constant fasl-type-vfasl-size 21)
-(define-constant fasl-type-fasl-size 22)
+(define-constant fasl-type-uninterned-symbol 21)
+(define-constant fasl-type-stencil-vector 22)
 (define-constant fasl-type-record 23)
 (define-constant fasl-type-rtd 24)
 (define-constant fasl-type-small-integer 25)
@@ -482,7 +482,7 @@
 (define-constant fasl-type-weak-pair 30)
 (define-constant fasl-type-eq-hashtable 31)
 (define-constant fasl-type-symbol-hashtable 32)
-; 33
+(define-constant fasl-type-phantom 33)
 (define-constant fasl-type-visit 34)
 (define-constant fasl-type-revisit 35)
 (define-constant fasl-type-visit-revisit 36)
@@ -493,11 +493,14 @@
 (define-constant fasl-type-immutable-bytevector 40)
 (define-constant fasl-type-immutable-box 41)
 
-(define-constant fasl-type-stencil-vector 42)
+(define-constant fasl-type-begin 42)
 
-(define-constant fasl-type-begin 43)
-(define-constant fasl-type-phantom 44)
-(define-constant fasl-type-uninterned-symbol 45)
+(define-constant fasl-type-uncompressed 43)
+(define-constant fasl-type-gzip 44)
+(define-constant fasl-type-lz4 45)
+
+(define-constant fasl-type-fasl 100)
+(define-constant fasl-type-vfasl 101)
 
 (define-constant fasl-type-terminator 127)
 
@@ -1532,6 +1535,8 @@
    [U64 instr-counter]
    [U64 alloc-counter]
    [ptr parameters]
+   [ptr DSTBV]
+   [ptr SRCBV]
    [double fpregs (constant asm-fpreg-max)]))
 
 (define tc-field-list
diff --git a/s/compile.ss b/s/compile.ss
index 41763d2f32..16ceb4a94f 100644
--- a/s/compile.ss
+++ b/s/compile.ss
@@ -1,4 +1,3 @@
-"compile.ss"
 ;;; compile.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -16,14 +15,6 @@
 
 ;;; use fixnum arithmetic in code building & output routines
 
-(define compile)
-(define $compile-backend)
-(define compile-file)
-(define $c-make-code)
-(define make-boot-header)
-(define make-boot-file)
-(define vfasl-convert-file)
-
 (let ()
 (import (nanopass))
 (include "types.ss")
@@ -551,9 +542,9 @@
                    [enable-error-source-expression (enable-error-source-expression)]
                    [enable-unsafe-application (enable-unsafe-application)]
                    [enable-type-recovery (enable-type-recovery)])
-      (emit-header op (constant machine-type))
-      (when hostop (emit-header hostop (host-machine-type)))
-      (when wpoop (emit-header wpoop (host-machine-type)))
+      (emit-header op (constant scheme-version) (constant machine-type))
+      (when hostop (emit-header hostop (constant scheme-version) (host-machine-type)))
+      (when wpoop (emit-header wpoop (constant scheme-version) (host-machine-type)))
       (let cfh0 ([n 1] [rrcinfo** '()] [rlpinfo** '()] [rfinal** '()])
         (let ([x0 ($pass-time 'read do-read)])
           (if (eof-object? x0)
@@ -807,40 +798,30 @@
         (close-port op))))
 
   (define with-object-file
-    (case-lambda
-      [(who ofn p) (with-object-file who ofn #t p)]
-      [(who ofn compressed-okay? p)
-       (call-with-port/cleanup ofn
-         ($open-file-output-port who ofn
-           (if (and compressed-okay? (compile-compressed))
-               (file-options replace compressed)
-               (file-options replace)))
-         p)]))
+    (lambda (who ofn p)
+      (call-with-port/cleanup ofn
+        ($open-file-output-port who ofn
+          (file-options replace))
+        p)))
 
   (define with-host-file
     (lambda (who ofn p)
       (if ofn
           (call-with-port/cleanup ofn
             ($open-file-output-port who ofn
-              (if (compile-compressed)
-                  (file-options replace compressed)
-                  (file-options replace)))
+              (file-options replace))
             p)
           (p #f))))
 
   (define with-wpo-file
-    (case-lambda
-      [(who ofn p) (with-wpo-file who ofn #t p)]
-      [(who ofn compressed-okay? p)
-       (if (generate-wpo-files)
-           (let ([ofn (new-extension "wpo" ofn)])
-             (call-with-port/cleanup ofn
-               ($open-file-output-port who ofn
-                 (if (and compressed-okay? (compile-compressed))
-                     (file-options replace compressed)
-                     (file-options replace)))
-               p))
-           (p #f))]))
+    (lambda (who ofn p)
+      (if (generate-wpo-files)
+          (let ([ofn (new-extension "wpo" ofn)])
+            (call-with-port/cleanup ofn
+              ($open-file-output-port who ofn
+                (file-options replace))
+              p))
+          (p #f))))
 
   (define with-coverage-file
     (lambda (who ofn p)
@@ -859,7 +840,7 @@
 
 (set! $compile-host-library
   (lambda (who iofn)
-    (let ([ip ($open-file-input-port who iofn (file-options compressed))])
+    (let ([ip ($open-file-input-port who iofn)])
       (on-reset (close-port ip)
         (let loop ([rx1* '()] [rcinfo* '()] [rother* '()])
           (let ([x1 (fasl-read ip)])
@@ -870,7 +851,7 @@
                  (unless (null? rother*) ($oops 'compile-library "unexpected value ~s read from file ~s that also contains ~s" (car rother*) iofn (car rx1*)))
                  (with-object-file who iofn
                    (lambda (op)
-                     (emit-header op (constant machine-type))
+                     (emit-header op (constant scheme-version) (constant machine-type))
                        (let loop ([x1* (reverse rx1*)] [rrcinfo** (list rcinfo*)] [rlpinfo** '()] [rfinal** '()])
                          (if (null? x1*)
                              (compile-file-help2 op (reverse rrcinfo**) (reverse rlpinfo**) (reverse rfinal**))
@@ -950,7 +931,6 @@
                                    (loop)))))
                            (get-bv))
                          (begin (set-port-position! ip start-pos) #f)))])
-              (port-file-compressed! ip)
               (if ($compiled-file-header? ip)
                   (let loop ([rls '()])
                     (let ([x (fasl-read ip)])
@@ -993,7 +973,7 @@
               [else ($oops who "unable to locate expanded library file for library ~s" path)])))
         (define read-binary-file
           (lambda (path fn libs-visible?)
-            (call-with-port ($open-file-input-port who fn (file-options compressed))
+            (call-with-port ($open-file-input-port who fn)
               (lambda (ip)
                 (on-reset (close-port ip)
                   (if ($compiled-file-header? ip)
@@ -1570,18 +1550,17 @@
 
   (define finish-compile
     (lambda (who msg ifn ofn hash-bang-line x1)
-      (with-object-file who ofn #f
+      (with-object-file who ofn
         (lambda (op)
           (with-coverage-file who ofn
             (lambda (source-table)
               (when hash-bang-line (put-bytevector op hash-bang-line))
-              (when (compile-compressed) (port-file-compressed! op))
               (parameterize ([$target-machine (constant machine-type-name)]
                              ; dummy sfd for block-profile optimization
                              [$sfd (make-source-file-descriptor ifn #xc7 #xc7c7)]
                              [$block-counter 0])
                 (when source-table ($insert-profile-src! source-table x1))
-                (emit-header op (constant machine-type))
+                (emit-header op (constant scheme-version) (constant machine-type))
                 (let-values ([(rcinfo* lpinfo* final*) (compile-file-help1 x1 msg)])
                   (compile-file-help2 op (list rcinfo*) (list lpinfo*) (list final*))))))))))
 
@@ -1590,7 +1569,7 @@
       (with-wpo-file who ofn
         (lambda (wpoop)
           (when wpoop
-            (emit-header wpoop (host-machine-type))
+            (emit-header wpoop (constant scheme-version) (host-machine-type))
             ($with-fasl-target (host-machine-type)
               (lambda ()
                 (parameterize ([$target-machine (machine-type)])
@@ -1732,7 +1711,7 @@
 (let ()
   (define emit-boot-header
     (lambda (op machine bootfiles)
-      (emit-header op (constant machine-type) (map path-root (map path-last bootfiles)))
+      (emit-header op (constant scheme-version) (constant machine-type) (map path-root (map path-last bootfiles)))
       (when (null? bootfiles)
         (parameterize ([$target-machine machine] [$sfd #f])
           (c-print-fasl ($np-boot-code 'error-invoke) op (constant fasl-type-visit-revisit))
@@ -1758,7 +1737,7 @@
                 (emit-boot-header op machine bootfile*))
               (for-each
                 (lambda (infn)
-                  (let ([ip ($open-file-input-port who infn (file-options compressed))])
+                  (let ([ip ($open-file-input-port who infn)])
                     (on-reset (close-port ip)
                       (if ($compiled-file-header? ip)
                           (begin
@@ -1822,26 +1801,23 @@
     (let ([->vfasl (foreign-procedure "(cs)to_vfasl" (scheme-object) scheme-object)]
           [vfasl-can-combine? (foreign-procedure "(cs)vfasl_can_combinep" (scheme-object) boolean)])
       (lambda (in-file out-file bootfile*)
-        (let ([op ($open-file-output-port who out-file
-                    (if (compile-compressed)
-                        (file-options replace compressed)
-                        (file-options replace)))])
+        (let ([op ($open-file-output-port who out-file (file-options replace))])
           (on-reset (delete-file out-file #f)
             (on-reset (close-port op)
               (when bootfile*
                 (emit-boot-header op (constant machine-type-name) bootfile*))
+              (emit-header op (constant scheme-version) (constant machine-type))
               (let ([ip ($open-file-input-port who in-file (file-options compressed))])
                 (on-reset (close-port ip)
                   (let* ([write-out (lambda (x)
-                                      (emit-header op (constant machine-type))
                                       (let ([bv (->vfasl x)])
-                                        (put-u8 op (constant fasl-type-visit-revisit))
-                                        (put-u8 op (constant fasl-type-vfasl-size))
-                                        (put-uptr op (bytevector-length bv))
-                                        (put-bytevector op bv)))]
+                                        ($write-fasl-bytevectors op (list bv) (bytevector-length bv)
+                                                                 (constant fasl-type-visit-revisit) (constant fasl-type-vfasl))))]
                          [write-out-accum (lambda (accum)
                                             (unless (null? accum)
-                                              (write-out (list->vector (reverse accum)))))])
+                                              (if (null? (cdr accum))
+                                                  (write-out (car accum))
+                                                  (write-out (list->vector (reverse accum))))))])
                     (let loop ([accum '()])
                       (let ([x (fasl-read ip)])
                         (cond
@@ -1856,7 +1832,45 @@
                          [else
                           (loop (cons x accum))]))))
                   (close-port ip)))
-              (close-port op))))))))
+              (close-port op)))))))
+  )
+
+(set-who! $write-fasl-bytevectors
+  (lambda (p bv* size situation kind)
+    (define (append-bvs bv*)
+      (if (and (pair? bv*)
+               (null? (cdr bv*)))
+          (car bv*)
+          (let f ([bv* bv*] [n 0])
+            (if (null? bv*)
+                (if (fixnum? n)
+                    (make-bytevector n)
+                    ($oops 'fasl-write "fasl output is too large to compress"))
+                (let ([bv1 (car bv*)])
+                  (let ([m (bytevector-length bv1)])
+                    (let ([bv2 (f (cdr bv*) (+ n m))])
+                      (bytevector-copy! bv1 0 bv2 n m)
+                      bv2)))))))
+    (put-u8 p situation)
+    (if (and (>= size 100) (fasl-compressed))
+        (let* ([fmt ($tc-field 'compress-format ($tc))]
+               [bv (append-bvs bv*)]
+               [uncompressed-size-bv (call-with-bytevector-output-port (lambda (bvp) (put-uptr bvp (bytevector-length bv))))]
+               [bv ($bytevector-compress bv fmt)])
+          (put-uptr p (+ 2 (bytevector-length uncompressed-size-bv) (bytevector-length bv)))
+          (put-u8 p 
+                  (cond
+                    [(eqv? fmt (constant COMPRESS-GZIP)) (constant fasl-type-gzip)]
+                    [(eqv? fmt (constant COMPRESS-LZ4)) (constant fasl-type-lz4)]
+                    [else ($oops 'fasl-write "unexpected $compress-format value ~s" fmt)]))
+          (put-u8 p kind)
+          (put-bytevector p uncompressed-size-bv)
+          (put-bytevector p bv))
+        (begin
+          (put-uptr p (+ size 2))
+          (put-u8 p (constant fasl-type-uncompressed))
+          (put-u8 p kind)
+          (for-each (lambda (bv) (put-bytevector p bv)) bv*)))))
 
 (let ()
   (define (libreq-hash x) (symbol-hash (libreq-uid x)))
@@ -1872,7 +1886,7 @@
               (let ([ip* (reverse rip*)])
                 (with-object-file who outfn
                   (lambda (op)
-                    (emit-header op (constant machine-type))
+                    (emit-header op (constant scheme-version) (constant machine-type))
                     (c-print-fasl `(object ,(make-recompile-info
                                               (vector->list (hashtable-keys import-ht))
                                               (vector->list (hashtable-keys include-ht))))
@@ -1903,7 +1917,6 @@
                      [ip ($open-file-input-port who fn)])
                 (on-reset (close-port ip)
                   ;; NB: Does not currently support files beginning with a #! line.  Add that here if desired.
-                  (port-file-compressed! ip)
                   (unless ($compiled-file-header? ip) ($oops who "missing header for compiled file ~s" fn))
                   (let ([rcinfo (fasl-read ip)])
                     (unless (recompile-info? rcinfo) ($oops who "expected recompile info at start of ~s, found ~a" fn rcinfo))
@@ -1936,12 +1949,14 @@
          ($oops who "~s is not a textual input port" ip))
        (unless (and (output-port? op) (binary-port? op))
          ($oops who "~s is not a binary output port" op))
+       (when ($port-flags-set? op (constant port-flag-compressed)) ($compressed-warning who op))
        (when sfd
          (unless (source-file-descriptor? sfd)
            ($oops who "~s is not a source-file descriptor or #f" sfd)))
        (when wpoop
          (unless (and (output-port? wpoop) (binary-port? wpoop))
-           ($oops who "~s is not a binary output port or #f" wpoop)))
+           ($oops who "~s is not a binary output port or #f" wpoop))
+         (when ($port-flags-set? wpoop (constant port-flag-compressed)) ($compressed-warning who wpoop)))
        (when covop
          (unless (and (output-port? covop) (textual-port? covop))
            ($oops who "~s is not a textual output port or #f" covop)))
@@ -1950,7 +1965,8 @@
          ($oops who "compiler for ~s is not loaded" machine))
        (when hostop
          (unless (and (output-port? hostop) (binary-port? hostop))
-           ($oops who "~s is not a binary output port or #f" hostop)))
+           ($oops who "~s is not a binary output port or #f" hostop))
+         (when ($port-flags-set? hostop (constant port-flag-compressed)) ($compressed-warning who hostop)))
        (let ([source-table (and covop (make-source-table))])
          (let ([fp (and (port-has-port-position? ip)
                         (let ([fp (port-position ip)])
@@ -1985,12 +2001,14 @@
          ($oops who "~s is not a proper list" sexpr*))
        (unless (and (output-port? op) (binary-port? op))
          ($oops who "~s is not a binary output port" op))
+       (when ($port-flags-set? op (constant port-flag-compressed)) ($compressed-warning who op))
        (when sfd
          (unless (source-file-descriptor? sfd)
            ($oops who "~s is not a source-file descriptor or #f" sfd)))
        (when wpoop
          (unless (and (output-port? wpoop) (binary-port? wpoop))
-           ($oops who "~s is not a binary output port or #f" wpoop)))
+           ($oops who "~s is not a binary output port or #f" wpoop))
+         (when ($port-flags-set? wpoop (constant port-flag-compressed)) ($compressed-warning who wpoop)))
        (when covop
          (unless (and (output-port? covop) (textual-port? covop))
            ($oops who "~s is not a textual output port or #f" covop)))
@@ -1999,7 +2017,8 @@
          ($oops who "compiler for ~s is not loaded" machine))
        (when hostop
          (unless (and (output-port? hostop) (binary-port? hostop))
-           ($oops who "~s is not a binary output port or #f" hostop)))
+           ($oops who "~s is not a binary output port or #f" hostop))
+         (when ($port-flags-set? hostop (constant port-flag-compressed)) ($compressed-warning who hostop)))
        (if (and (= (length sexpr*) 1) (pair? (car sexpr*)) (eq? (caar sexpr*) 'top-level-program))
            (let ([library-collector (make-parameter '())])
              (parameterize ([$require-libraries library-collector])
@@ -2080,10 +2099,10 @@
             (if (and (eqv? (read-char ip) #\#)
                      (eqv? (read-char ip) #\!)
                      (memv (lookahead-char ip) '(#\space #\/)))
-                ; copy #! line.  open output file w/o compression
-                (with-object-file who out #f
+                ; copy #! line
+                (with-object-file who out
                   (lambda (op)
-                    (with-wpo-file who out #f
+                    (with-wpo-file who out
                       (lambda (wpoop)
                         (with-coverage-file who out
                           (lambda (source-table)
@@ -2104,12 +2123,8 @@
                                             (when wpoop (put-u8 wpoop n)))
                                           (let ([fp (+ fp 1)])
                                             (if (char=? c #\newline) fp (loop fp)))))])
-                              ; compress remainder of file if requeseted
-                              (when (compile-compressed)
-                                (port-file-compressed! op)
-                                (when wpoop (port-file-compressed! wpoop)))
                               (compile-file-help op #f wpoop source-table machine sfd ((if r6rs? $make-read-program $make-read) ip sfd fp) out))))))))
-                ; no #! line.  open output file w/ compression, if so directed
+                ; no #! line
                 (with-object-file who out
                   (lambda (op)
                     (set-port-position! ip start-pos)
diff --git a/s/cp0.ss b/s/cp0.ss
index 74825ca0ae..b6b865a3cc 100644
--- a/s/cp0.ss
+++ b/s/cp0.ss
@@ -1,4 +1,3 @@
-"cp0"
 ;;; cp0.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
diff --git a/s/cpcommonize.ss b/s/cpcommonize.ss
index dd29d5944f..18ef45661f 100644
--- a/s/cpcommonize.ss
+++ b/s/cpcommonize.ss
@@ -1,4 +1,3 @@
-"cpcommonize.ss"
 ;;; cpcommonize.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,6 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 (define-who commonization-level
   ($make-thread-parameter
     0
@@ -576,3 +576,4 @@
             x
             (let ([worthwhile-size (expt 2 (fx- 10 level))])
               (cpcommonize2 (cpcommonize1 (cpcommonize0 x) worthwhile-size))))))))
+)
diff --git a/s/cpletrec.ss b/s/cpletrec.ss
index 2bb04998a8..5b4cfb2055 100644
--- a/s/cpletrec.ss
+++ b/s/cpletrec.ss
@@ -1,4 +1,3 @@
-"cpletrec.ss"
 ;;; cpletrec.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
diff --git a/s/cpnanopass.ss b/s/cpnanopass.ss
index ea88226b37..63571eeecd 100644
--- a/s/cpnanopass.ss
+++ b/s/cpnanopass.ss
@@ -1,4 +1,3 @@
-"cpnanopass.ss"
 ;;; cpnanopass.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;;
@@ -18201,6 +18200,6 @@
   (set! $track-dynamic-closure-counts track-dynamic-closure-counts)
 
   (set! $track-static-closure-counts track-static-closure-counts)
-)
 
-(define $optimize-closures (make-parameter #t (lambda (x) (and x #t))))
+  (set! $optimize-closures (make-parameter #t (lambda (x) (and x #t))))
+)
diff --git a/s/cprep.ss b/s/cprep.ss
index e8e969f12a..e43357de62 100644
--- a/s/cprep.ss
+++ b/s/cprep.ss
@@ -1,4 +1,3 @@
-"cprep.ss"
 ;;; cprep.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
diff --git a/s/cpvalid.ss b/s/cpvalid.ss
index 3b63f5cb54..00edf94c72 100644
--- a/s/cpvalid.ss
+++ b/s/cpvalid.ss
@@ -1,4 +1,3 @@
-"cpvalid.ss"
 ;;; cpvalid.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -17,10 +16,10 @@
 ;;; see comments relating to both cpvalid and cpletrec at front of
 ;;; cpletrec.ss
 
+(begin
 (define undefined-variable-warnings
   ($make-thread-parameter #f (lambda (x) (and x #t))))
 
-(define $cpvalid)
 (let ()
   (import (nanopass))
   (include "base-lang.ss")
@@ -572,3 +571,4 @@
               (enable-unsafe-variable-reference))
           x
           (cpvalid x)))))
+)
diff --git a/s/date.ss b/s/date.ss
index 6527372738..1dbbba37f4 100644
--- a/s/date.ss
+++ b/s/date.ss
@@ -1,4 +1,3 @@
-"date.ss"
 ;;; date.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
diff --git a/s/engine.ss b/s/engine.ss
index d23dc432a5..01fea2b650 100644
--- a/s/engine.ss
+++ b/s/engine.ss
@@ -1,4 +1,3 @@
-"engine.ss"
 ;;; engine.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -29,10 +28,6 @@
 ;;;   *timer*   the saved timer interrupt handler
 
 
-(define make-engine)
-(define engine-block)
-(define engine-return)
-
 (let ()
 
 (define-threaded *exit*)
diff --git a/s/enum.ss b/s/enum.ss
index faa76c48ff..b5384ad216 100644
--- a/s/enum.ss
+++ b/s/enum.ss
@@ -1,4 +1,3 @@
-"enum.ss"
 ;;; enum.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -27,24 +26,6 @@
 ;;  should throw an error if its argument is not a symbol.  We have chosen to
 ;;  not include that check, but if the standard is updated, this may need to be changed.
 
-(define $enum-set-members)
-
-(define enum-set?)
-(define make-enumeration)
-(define enum-set-universe)
-(define enum-set-indexer)
-(define enum-set-constructor)
-(define enum-set->list)
-(define enum-set-member?)
-(define enum-set-subset?)
-(define enum-set=?)
-(define enum-set-union)
-(define enum-set-intersection)
-(define enum-set-difference)
-(define enum-set-complement)
-(define enum-set-projection)
-
-
 (let ()
 
 ;;;;;;;;
diff --git a/s/env.ss b/s/env.ss
index 9be6eae36a..3c653be6c4 100644
--- a/s/env.ss
+++ b/s/env.ss
@@ -1,4 +1,3 @@
-"env.ss"
 ;;; env.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,5 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 ($make-base-modules)
 ($make-rnrs-libraries)
+)
diff --git a/s/event.ss b/s/event.ss
index 042167936d..a1dd6e712f 100644
--- a/s/event.ss
+++ b/s/event.ss
@@ -1,4 +1,3 @@
-"event.ss"
 ;;; event.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,10 +13,6 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
-(define set-timer)
-(define enable-interrupts)
-(define disable-interrupts)
-
 (let ()
 (define stop-event-timer
    (lambda ()
diff --git a/s/exceptions.ss b/s/exceptions.ss
index c1998059e8..562a8e84fa 100644
--- a/s/exceptions.ss
+++ b/s/exceptions.ss
@@ -1,4 +1,3 @@
-"exceptions.ss"
 ;;; exceptions.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -29,6 +28,7 @@ TODO:
  - deal with error? and warning? mats
 |#
 
+(begin
 (let ()
   (define (warning-only? c)
     (and (warning? c) (not (serious-condition? c))))
@@ -739,3 +739,4 @@ TODO:
             (condition fwcond ($make-src-condition src start?))
             fwcond))))
 )
+)
diff --git a/s/expeditor.ss b/s/expeditor.ss
index 04e554d4b6..11204209bc 100644
--- a/s/expeditor.ss
+++ b/s/expeditor.ss
@@ -1,4 +1,3 @@
-"expeditor.ss"
 ;;; expeditor.ss
 ;;; R. Kent Dybvig
 ;;; August 2007
diff --git a/s/fasl-helpers.ss b/s/fasl-helpers.ss
index d60bbb570a..a2c27cef3c 100644
--- a/s/fasl-helpers.ss
+++ b/s/fasl-helpers.ss
@@ -135,8 +135,8 @@
 
 (define emit-header
   (case-lambda
-    [(p mtype) (emit-header p mtype '())]
-    [(p mtype bootfiles)
+    [(p version mtype) (emit-header p version mtype '())]
+    [(p version mtype bootfiles)
      (define (put-str p s)
        (let ([n (string-length s)])
          (do ([i 0 (fx+ i 1)])
@@ -146,7 +146,7 @@
                ($oops #f "cannot handle bootfile name character ~s whose integer code exceeds 255" c))
              (put-u8 p k)))))
      (put-bytevector p (constant fasl-header))
-     (put-uptr p (constant scheme-version))
+     (put-uptr p version)
      (put-uptr p mtype)
      (put-u8 p (char->integer #\())           ; )
      (let f ([bootfiles bootfiles] [sep? #f])
diff --git a/s/fasl.ss b/s/fasl.ss
index e41f94495e..18ce2e4040 100644
--- a/s/fasl.ss
+++ b/s/fasl.ss
@@ -1,4 +1,3 @@
-"fasl.ss"
 ;;; fasl.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -659,10 +658,7 @@
                                     begins)))
                       (proc p)
                       (extractor))])
-        (put-u8 p situation)
-        (put-u8 p (constant fasl-type-fasl-size))
-        (put-uptr p size)
-        (for-each (lambda (bv) (put-bytevector p bv)) bv*))))
+        ($write-fasl-bytevectors p bv* size situation (constant fasl-type-fasl)))))
 
   (define (extract-begins t)
     (let ([ht (table-hash t)])
@@ -700,7 +696,8 @@
     (lambda (x p)
       (unless (and (output-port? p) (binary-port? p))
         ($oops who "~s is not a binary output port" p))
-      (emit-header p (constant machine-type-any))
+      (when ($port-flags-set? p (constant port-flag-compressed)) ($compressed-warning who p))
+      (emit-header p (constant scheme-version) (constant machine-type-any))
       (fasl-one x p)))
 
   (define-who fasl-file
@@ -716,7 +713,7 @@
             (delete-file out #f))
           (on-reset
             (close-port op)
-            (emit-header op (constant machine-type-any))
+            (emit-header op (constant scheme-version) (constant machine-type-any))
             (let fasl-loop ()
               (let ([x (read ip)])
                 (unless (eof-object? x)
@@ -727,7 +724,7 @@
 
 (define fasl-base-rtd
   (lambda (x p)
-    (emit-header p (constant machine-type-any))
+    (emit-header p (constant scheme-version) (constant machine-type-any))
     (let ([t (make-table)])
       (bld-graph x t #f 0 #t really-bld-record)
       (start p t (constant fasl-type-visit-revisit) (lambda (p) (wrf-graph x p t #f really-wrf-record))))))
@@ -750,7 +747,6 @@
   (set! $fasl-base-rtd (lambda (x p) ((target-fasl-base-rtd (fasl-target)) x p)))
   (set! fasl-write (lambda (x p) ((target-fasl-write (fasl-target)) x p)))
   (set! fasl-file (lambda (in out) ((target-fasl-file (fasl-target)) in out))))
-)
 
 (when ($unbound-object? (#%$top-level-value '$capture-fasl-target))
   (let ([ht (make-hashtable values =)])
@@ -767,3 +763,4 @@
           [else ($oops who "unrecognized machine type ~s" mt)])))))
   
 ($capture-fasl-target (constant machine-type))
+)
diff --git a/s/foreign.ss b/s/foreign.ss
index 4420780756..d68c32e152 100644
--- a/s/foreign.ss
+++ b/s/foreign.ss
@@ -1,4 +1,3 @@
-"foreign.ss"
 ;;; foreign.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,10 +13,6 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
-"foreign.ss"
-(define remove-foreign-entry)
-(define load-shared-object)
-(define foreign-entry?)
 (let ()
    (define $foreign-address-name
       (foreign-procedure "(cs)foreign_address_name" (void*)
diff --git a/s/format.ss b/s/format.ss
index f42712d973..fed633d3b0 100644
--- a/s/format.ss
+++ b/s/format.ss
@@ -1,4 +1,3 @@
-"format.ss"
 ;;; format.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
diff --git a/s/front.ss b/s/front.ss
index 402973f8dc..d6ff185fce 100644
--- a/s/front.ss
+++ b/s/front.ss
@@ -1,4 +1,3 @@
-"front.ss"
 ;;; front.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,6 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 (define-who make-parameter
   (case-lambda
     [(init guard) (#2%make-parameter init guard)]
@@ -269,3 +269,4 @@
     [(x env-spec records? compiling-a-file outfn) ((current-expand) x env-spec records? compiling-a-file outfn)]))
 
 (define $compiler-is-loaded? #f)
+)
diff --git a/s/ftype.ss b/s/ftype.ss
index ce9ab7108b..fea18e0381 100644
--- a/s/ftype.ss
+++ b/s/ftype.ss
@@ -1,4 +1,3 @@
-"ftype.ss"
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
 ;;; Licensed under the Apache License, Version 2.0 (the "License");
@@ -228,6 +227,7 @@ ftype operators:
    appropriate size for int and unsigned.
 |#
 
+(begin
 (let ()
   (include "types.ss")
   (define-syntax rtd/fptr
@@ -2057,3 +2057,4 @@ ftype operators:
 (define-syntax ftype-spin-lock! (lambda (x) ($trans-ftype-locked-op! #'ftype-spin-lock! x #'$fptr-spin-lock!)))
 (define-syntax ftype-unlock! (lambda (x) ($trans-ftype-locked-op! #'ftype-unlock! x #'$fptr-unlock!)))
 (define-syntax ftype-set! (lambda (x) ($trans-ftype-set! x)))
+)
diff --git a/s/inspect.ss b/s/inspect.ss
index 1bd56e3fd8..7f28535e66 100644
--- a/s/inspect.ss
+++ b/s/inspect.ss
@@ -1,4 +1,3 @@
-"inspect.ss"
 ;;; inspect.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -29,8 +28,7 @@
 ; ---port info should include file descriptor, perhaps provide access
 ;    location in file
 
-(define inspect)
-
+(begin
 (let ()
 
 (define-syntax make-dispatch-table
@@ -3074,3 +3072,5 @@
 (define object-counts (foreign-procedure "(cs)object_counts" () ptr))
 
 (define object-backreferences (foreign-procedure "(cs)object_backreferences" () ptr))
+
+)
diff --git a/s/interpret.ss b/s/interpret.ss
index 11a7dcf2d7..896a1cc87c 100644
--- a/s/interpret.ss
+++ b/s/interpret.ss
@@ -1,4 +1,3 @@
-"interpret.ss"
 ;;; interpret.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -730,6 +729,6 @@
 (set! $interpret-backend
   (lambda (x situation for-import? importer ofn)
     (interpret-Lexpand x situation for-import? importer ofn (expand/optimize-output))))
+(current-eval interpret)
 )
 
-(current-eval interpret)
diff --git a/s/io.ss b/s/io.ss
index bf52ffb571..541a7f39a5 100644
--- a/s/io.ss
+++ b/s/io.ss
@@ -1,4 +1,3 @@
-"io.ss"
 ;;; io.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;;
@@ -80,6 +79,7 @@ implementation notes:
     so we instead use an input-mode flag in the port header.
 |#
 
+(begin
 (set-who! file-buffer-size
   ($make-thread-parameter $c-bufsiz
     (lambda (x)
@@ -6307,3 +6307,4 @@ implementation notes:
   ; utf8->string, etc., are in prims.ss, since they are used by
   ; foreign procedures argument and return values
 )
+)
diff --git a/s/library.ss b/s/library.ss
index bddad668a8..274d45c037 100644
--- a/s/library.ss
+++ b/s/library.ss
@@ -27,8 +27,6 @@
    (generate-interrupt-trap #f)
    ($track-dynamic-closure-counts #f))
 
-"library.ss (includes #<void> just before)"
-
 (eval-when (compile)
 (define-syntax define-library-entry
   (lambda (x)
@@ -142,8 +140,6 @@
 ;;; set up $nuate for overflow
 (define $nuate ($closure-code (call/1cc (lambda (k) k))))
 
-"making closure counters!"
-
 (set! #{raw-ref-count bhowt6w0coxl0s2y-1} '#[#{profile-counter b5vnnom9h4o4uny0-2} 0])
 (set! #{raw-create-count bhowt6w0coxl0s2y-2} '#[#{profile-counter b5vnnom9h4o4uny0-2} 0])
 (set! #{raw-alloc-count bhowt6w0coxl0s2y-3} '#[#{profile-counter b5vnnom9h4o4uny0-2} 0])
diff --git a/s/mathprims.ss b/s/mathprims.ss
index 381f807469..2f5b7648b1 100644
--- a/s/mathprims.ss
+++ b/s/mathprims.ss
@@ -1,4 +1,3 @@
-"mathprims.ss"
 ;;; mathprims.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,6 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 (eval-when (compile)
 
   (define-syntax define-relop
@@ -771,3 +771,4 @@
          [else (noncflonum-error 'cfl-conjugate x)])))
 
 )
+)
diff --git a/s/mkgc.ss b/s/mkgc.ss
index a30a2da9eb..107b5a2a4b 100644
--- a/s/mkgc.ss
+++ b/s/mkgc.ss
@@ -953,6 +953,11 @@
       (trace (tc-compress-format tc))
       (trace (tc-compress-level tc))
       (trace (tc-parameters tc))
+      (case-mode
+       [(sweep)
+        (set! (tc-DSTBV tc) Sfalse)
+        (set! (tc-SRCBV tc) Sfalse)]
+       [else])
       (let* ([i : INT 0])
         (while
          :? (< i virtual_register_count)
diff --git a/s/newhash.ss b/s/newhash.ss
index 4a17c2c9a7..0dcbc6c5cb 100644
--- a/s/newhash.ss
+++ b/s/newhash.ss
@@ -1,4 +1,3 @@
-"newhash.ss"
 ;;; newhash.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
diff --git a/s/pdhtml.ss b/s/pdhtml.ss
index 15e929e2a4..5d45e24f6e 100644
--- a/s/pdhtml.ss
+++ b/s/pdhtml.ss
@@ -1,4 +1,3 @@
-"pdhtml.ss"
 ;;; pdhtml.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;;
@@ -56,6 +55,7 @@
 ;;;  source annotation around the transformer output so that the source info for t>
 ;;;  when expression is transferred to the generated if expression.
 
+(begin
 (let ()
   (include "types.ss")
   (module (make-tracker tracker-profile-ct)
@@ -1535,3 +1535,4 @@
         (unless (or (eq? color #f) (string? color)) ($oops who "~s is not a string or #f" color))
         color)))
 )
+)
diff --git a/s/pretty.ss b/s/pretty.ss
index 5d4e995d67..3127334d94 100644
--- a/s/pretty.ss
+++ b/s/pretty.ss
@@ -1,4 +1,3 @@
-"pretty.ss"
 ;;; pretty.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -24,6 +23,7 @@
 ;;;; EXPORTED VARIABLES
 
 ;;; pretty tries to fit things within line length
+(begin
 (define pretty-line-length
    ($make-thread-parameter
       75
@@ -797,3 +797,4 @@
     (wr (prty-obj x) p)
     (write-char #\> p)))
 )
+)
diff --git a/s/primdata.ss b/s/primdata.ss
index 182cde33fa..5539bb54bd 100644
--- a/s/primdata.ss
+++ b/s/primdata.ss
@@ -921,7 +921,6 @@
   (command-line [sig [() -> (list)] [(sub-list) -> (void)]] [flags])  ; not restricted to 1 argument
   (command-line-arguments [sig [() -> (list)] [(sub-list) -> (void)]] [flags])
   (commonization-level [sig [() -> (ufixnum)] [(sub-ufixnum) -> (void)]] [flags])
-  (compile-compressed [sig [() -> (boolean)] [(ptr) -> (void)]] [flags unrestricted])
   (compile-file-message [sig [() -> (boolean)] [(ptr) -> (void)]] [flags unrestricted])
   (compile-interpret-simple [sig [() -> (boolean)] [(ptr) -> (void)]] [flags unrestricted])
   (compile-imported-libraries [sig [() -> (boolean)] [(ptr) -> (void)]] [flags unrestricted])
@@ -966,6 +965,7 @@
   (expand-output [sig [() -> (maybe-textual-output-port)] [(maybe-textual-output-port) -> (void)]] [flags])
   (expand/optimize-output [sig [() -> (maybe-textual-output-port)] [(maybe-textual-output-port) -> (void)]] [flags])
   (exit-handler [sig [() -> (procedure)] [(procedure) -> (void)]] [flags])
+  (fasl-compressed [sig [() -> (boolean)] [(ptr) -> (void)]] [flags unrestricted])
   (file-buffer-size [sig [() -> (ufixnum)] [(sub-fixnum) -> (void)]] [flags])
   (generate-allocation-counts [sig [() -> (boolean)] [(ptr) -> (void)]] [flags unrestricted])
   (generate-covin-files [sig [() -> (boolean)] [(ptr) -> (void)]] [flags unrestricted])
@@ -1831,10 +1831,12 @@
   ($build-invoke-program [flags single-valued])
   ($build-library-exts [flags single-valued])
   ($byte-copy! [flags single-valued])
+  ($bytevector-compress [flags])
   ($bytevector-ref-check? [sig [(sub-uint ptr ptr) -> (boolean)]] [flags pure])
   ($bytevector-set!-check? [sig [(sub-uint ptr ptr) -> (boolean)]] [flags discard])
   ($bytevector-set! [flags single-valued])
   ($bytevector-set-immutable! [sig [(bytevector) -> (void)]] [flags true])
+  ($bytevector-uncompress [flags])
   ($capture-fasl-target [flags single-valued])
   ($c-error [flags])
   ($check-heap-errors [flags single-valued])
@@ -1865,6 +1867,7 @@
   ($compile-host-library [flags single-valued])
   ($compound-condition-components [flags discard true])
   ($compound-condition? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable])
+  ($compressed-warning [flags])
   ($compute-composition [flags single-valued])
   ($compute-size [flags single-valued])
   ($constituent?  [sig [(char) -> (boolean)]] [flags pure mifoldable safeongoodargs])
@@ -2394,6 +2397,7 @@
   ($visit [flags single-valued])
   ($visit-library [flags single-valued])
   ($with-fasl-target [flags single-valued])
+  ($write-fasl-bytevectors [flags single-valued])
   ($write-pretty-quick [flags single-valued])
   ($xscript-port? [sig [(port) -> (boolean)]] [flags discard])
 )
diff --git a/s/prims.ss b/s/prims.ss
index 2cf077a0e7..1496e74913 100644
--- a/s/prims.ss
+++ b/s/prims.ss
@@ -1,4 +1,3 @@
-"prims.ss"
 ;;; prims.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -19,6 +18,7 @@
    (run-cp0 (default-run-cp0))
    (generate-interrupt-trap #f))
 
+(begin
 ;;; hand-coded primitives
 
 (define-who $hand-coded
@@ -2679,3 +2679,5 @@
   (lambda (x v)
     (unless (wrapper-procedure? x) ($oops who "~s is not a wrapper procedure" x))
     ($closure-set! x 2 v)))
+
+)
diff --git a/s/primvars.ss b/s/primvars.ss
index 9e5523a675..bc8dd2806f 100644
--- a/s/primvars.ss
+++ b/s/primvars.ss
@@ -1,4 +1,3 @@
-"primvars.ss"
 ;;; primvars.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
diff --git a/s/print.ss b/s/print.ss
index 3e6c216f1d..19bf1f2d74 100644
--- a/s/print.ss
+++ b/s/print.ss
@@ -1,4 +1,3 @@
-"print.ss"
 ;;; print.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;;
@@ -14,6 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 (eval-when (compile)
 (define-constant cycle-node-max 1000)
 
@@ -611,7 +611,7 @@ floating point returns with (1 0 -1 ...).
 (define wrhelp
    (lambda (x r lev len d? env p)
      (define void? (lambda (x) (eq? x (void))))
-     (define black-hole? (lambda (x) (eq? x '#0=#0#)))
+     (define black-hole? (lambda (x) (eq? x '#3=#3#)))
      (define base-rtd? (lambda (x) (eq? x #!base-rtd)))
      (if-feature pthreads
        (begin
@@ -1383,3 +1383,4 @@ floating point returns with (1 0 -1 ...).
       (unless (or (not x) (and (fixnum? x) (fx> x 0)) (and (bignum? x) ($bigpositive? x)))
         ($oops 'print-precision "~s is not a positive exact integer or #f" x))
       x)))
+)
diff --git a/s/read.ss b/s/read.ss
index b71e21935d..c0efc00da0 100644
--- a/s/read.ss
+++ b/s/read.ss
@@ -1,4 +1,3 @@
-"read.ss"
 ;;; read.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -18,6 +17,7 @@
 ;(define read)
 ;(define $read)
 
+(begin
 (let ()
 (include "types.ss")
 
@@ -1872,3 +1872,4 @@
   (char-name 'alarm #\bel)
   (char-name 'nel #\nel)
   (char-name 'ls #\ls))
+)
diff --git a/s/record.ss b/s/record.ss
index 335b4eb6aa..140f386c16 100644
--- a/s/record.ss
+++ b/s/record.ss
@@ -1,4 +1,3 @@
-"record.ss"
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
 ;;; Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/s/reloc.ss b/s/reloc.ss
index 60261c0a4a..f93691232f 100644
--- a/s/reloc.ss
+++ b/s/reloc.ss
@@ -1,4 +1,3 @@
-"reloc.ss"
 ;;; reloc.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -14,6 +13,7 @@
 ;;; See the License for the specific language governing permissions and
 ;;; limitations under the License.
 
+(begin
 (define $reloc
   (lambda (type item-offset code-offset)
     (make-reloc type item-offset code-offset
@@ -57,8 +57,6 @@
                         (bitwise-arithmetic-shift-left (reloc-item-offset r) (constant reloc-item-offset-offset))))
                     (mkc1 r* (fx+ n 1))))))))))
 
-(define $make-cinst)
-(define $make-vtable)
 (let ()
 (set! $make-cinst
   (lambda (build-sinst vtable)
@@ -100,3 +98,4 @@
                         r)
                   (constant ptr-bytes)))))))
 )
+)
diff --git a/s/strip.ss b/s/strip.ss
index f1a95c5a5b..a933eac0b2 100644
--- a/s/strip.ss
+++ b/s/strip.ss
@@ -89,6 +89,14 @@
                 (let ([k (read-byte p)])
                   (f k (logor (ash n 7) (fxand k #x7F))))
                 n)))))
+    (define read-uptr/bytes
+      (lambda (p)
+        (let ([k (read-byte p)])
+          (let f ([k k] [n (fxand k #x7F)] [bytes 1])
+            (if (fxlogbit? 7 k)
+                (let ([k (read-byte p)])
+                  (f k (logor (ash n 7) (fxand k #x7F)) (fx+ bytes 1)))
+                (values n bytes))))))
     (define read-byte-or-eof
       (lambda (p)
         (get-u8 p)))
@@ -101,6 +109,12 @@
       (let ([y (read-byte p)])
         (unless (eqv? y x)
           (bogus "expected byte ~s, got ~s from ~a" x y (port-name p)))))
+    (define read-bytevector
+      (lambda (p n)
+        (let ([bv (make-bytevector n)])
+          (do ([i 0 (fx+ i 1)])
+              ((fx= i n) bv)
+            (bytevector-u8-set! bv i (read-byte p))))))
     (define read-string
       (lambda (p)
         (let ([n (read-uptr p)])
@@ -116,13 +130,24 @@
             (fasl-type-case ty
               [(fasl-type-header) (read-header p)]
               [(fasl-type-visit fasl-type-revisit fasl-type-visit-revisit)
-               (let ([situation ty])
-                 (let ([ty (read-byte p)])
-                   (fasl-type-case ty
-                     [(fasl-type-fasl-size)
-                      (let ([size (read-uptr p)])
-                        (fasl-entry situation (read-fasl p #f)))]
-                     [else (bogus "expected fasl-size in ~a" (port-name p))])))]
+               (let* ([situation ty]
+                      [size (read-uptr p)]
+                      [compressed-flag (read-byte p)]
+                      [kind (read-byte p)])
+                 (unless (eqv? kind (constant fasl-type-fasl))
+                   (bogus "unexpected fasl kind ~a" (port-name p)))
+                 (fasl-type-case compressed-flag
+                   [(fasl-type-gzip fasl-type-lz4)
+                    (let-values ([(dest-size dest-size-bytes) (read-uptr/bytes p)])
+                      (let* ([src-size (- size 2 dest-size-bytes)]
+                             [bv (read-bytevector p src-size)]
+                             [bv ($bytevector-uncompress bv 0 src-size dest-size
+                                   (if (eqv? compressed-flag (constant fasl-type-gzip))
+                                       (constant COMPRESS-GZIP)
+                                       (constant COMPRESS-LZ4)))])
+                        (fasl-entry situation (read-fasl (open-bytevector-input-port bv) #f))))]
+                   [(fasl-type-uncompressed) (fasl-entry situation (read-fasl p #f))]
+                   [else (bogus "expected compression flag in ~a" (port-name p))]))]
               [else (bogus "expected header or situation in ~a" (port-name p))]))))
     (define (read-header p)
       (let* ([bv (constant fasl-header)] [n (bytevector-length bv)])
@@ -203,13 +228,7 @@
                      ((fx= i n) v)
                    (vector-set! v i (read-iptr p))))))]
           [(fasl-type-bytevector fasl-type-immutable-bytevector)
-           (fasl-bytevector
-             ty
-             (let ([n (read-uptr p)])
-               (let ([bv (make-bytevector n)])
-                 (do ([i 0 (fx+ i 1)])
-                     ((fx= i n) bv)
-                   (bytevector-u8-set! bv i (read-byte p))))))]
+           (fasl-bytevector ty (read-bytevector p (read-uptr p)))]
           [(fasl-type-base-rtd) (fasl-tuple ty '#())]
           [(fasl-type-rtd) (read-record p g (read-fasl p g))]
           [(fasl-type-record) (read-record p g #f)]
@@ -446,52 +465,44 @@
           [reloc (type-etc code-offset item-offset fasl) (build! fasl t)]
           [indirect (g i) (build! (vector-ref g i) t)])))
 
+    (include "fasl-helpers.ss")
+
     (define write-entry
       (lambda (p x)
+        (define (append-bvs bv*)
+          (let f ([bv* bv*] [n 0])
+            (if (null? bv*)
+                (if (fixnum? n)
+                    (make-bytevector n)
+                    ($oops 'fasl-write "fasl output is too large to compress"))
+                (let ([bv1 (car bv*)])
+                  (let ([m (bytevector-length bv1)])
+                    (let ([bv2 (f (cdr bv*) (+ n m))])
+                      (bytevector-copy! bv1 0 bv2 n m)
+                      bv2))))))
         (fasl-case x
           [header (version machine dependencies)
-           (write-header p version machine dependencies)]
+           (emit-header p version machine dependencies)]
           [entry (situation fasl)
            (let ([t (make-table)])
              (build! fasl t)
-             (let ([bv (call-with-bytevector-output-port
-                         (lambda (p)
-                           (let ([n (table-count t)])
-                             (unless (fx= n 0)
-                               (write-byte p (constant fasl-type-graph))
-                               (write-uptr p n)))
-                           (write-fasl p t fasl)))])
-               (write-byte p situation)
-               (write-byte p (constant fasl-type-fasl-size))
-               (write-uptr p (bytevector-length bv))
-               (put-bytevector p bv)))]
+             ($fasl-start p t situation
+               (lambda (p) (write-fasl p t fasl))))]
           [else (sorry! "unrecognized top-level fasl-record-type ~s" x)])))
 
-    (define write-header
-      (lambda (p version machine dependencies)
-        (put-bytevector p (constant fasl-header))
-        (write-uptr p version)
-        (write-uptr p machine)
-        (write-byte p (char->integer #\())
-        (let f ([dependencies dependencies])
-          (unless (null? dependencies)
-            (write-byte p (car dependencies))
-            (f (cdr dependencies))))
-        (write-byte p (char->integer #\)))))
-
     (define write-graph
       (lambda (p t x th)
         (let ([a (eq-hashtable-ref (table-ht t) x #f)])
           (cond
             [(not a) (th)]
             [(cdr a)
-             (write-byte p (constant fasl-type-graph-def))
-             (write-uptr p (car a))
+             (put-u8 p (constant fasl-type-graph-def))
+             (put-uptr p (car a))
              (set-cdr! a #f)
              (th)]
             [else
-             (write-byte p (constant fasl-type-graph-ref))
-             (write-uptr p (car a))]))))
+             (put-u8 p (constant fasl-type-graph-ref))
+             (put-uptr p (car a))]))))
 
     (define write-fasl
       (lambda (p t x)
@@ -501,42 +512,42 @@
           [pair (vfasl)
            (write-graph p t x
              (lambda ()
-               (write-byte p (constant fasl-type-pair))
-               (write-uptr p (fx- (vector-length vfasl) 1))
+               (put-u8 p (constant fasl-type-pair))
+               (put-uptr p (fx- (vector-length vfasl) 1))
                (vector-for-each (lambda (fasl) (write-fasl p t fasl)) vfasl)))]
           [tuple (ty vfasl)
            (write-graph p t x
              (lambda ()
-               (write-byte p ty)
+               (put-u8 p ty)
                (vector-for-each (lambda (fasl) (write-fasl p t fasl)) vfasl)))]
           [string (ty string)
            (write-graph p t x
              (lambda ()
-               (write-byte p ty)
+               (put-u8 p ty)
                (write-string p string)))]
           [gensym (pname uname)
            (write-graph p t x
              (lambda ()
-               (write-byte p (constant fasl-type-gensym))
+               (put-u8 p (constant fasl-type-gensym))
                (write-string p pname)
                (write-string p uname)))]
           [vector (ty vfasl)
            (write-graph p t x
              (lambda ()
-               (write-byte p ty)
-               (write-uptr p (vector-length vfasl))
+               (put-u8 p ty)
+               (put-uptr p (vector-length vfasl))
                (vector-for-each (lambda (fasl) (write-fasl p t fasl)) vfasl)))]
           [fxvector (ty viptr)
            (write-graph p t x
              (lambda ()
-               (write-byte p ty)
-               (write-uptr p (vector-length viptr))
-               (vector-for-each (lambda (iptr) (write-iptr p iptr)) viptr)))]
+               (put-u8 p ty)
+               (put-uptr p (vector-length viptr))
+               (vector-for-each (lambda (iptr) (put-iptr p iptr)) viptr)))]
           [bytevector (ty bv)
            (write-graph p t x
              (lambda ()
-               (write-byte p ty)
-               (write-uptr p (bytevector-length bv))
+               (put-u8 p ty)
+               (put-uptr p (bytevector-length bv))
                (put-bytevector p bv)))]
           [record (maybe-uid size nflds rtd pad-ty* fld*)
            (if (and strip-source-annotations? (fasl-annotation? x))
@@ -545,51 +556,51 @@
                  (lambda ()
                    (if maybe-uid
                        (begin
-                         (write-byte p (constant fasl-type-rtd))
+                         (put-u8 p (constant fasl-type-rtd))
                          (write-fasl p t maybe-uid))
-                       (write-byte p (constant fasl-type-record)))
-                   (write-uptr p size)
-                   (write-uptr p nflds)
+                       (put-u8 p (constant fasl-type-record)))
+                   (put-uptr p size)
+                   (put-uptr p nflds)
                    (write-fasl p t rtd)
                    (for-each (lambda (pad-ty fld)
-                               (write-byte p pad-ty)
+                               (put-u8 p pad-ty)
                                (field-case fld
                                  [ptr (fasl) (write-fasl p t fasl)]
-                                 [byte (n) (write-byte p n)]
-                                 [iptr (n) (write-iptr p n)]
-                                 [single (n) (write-uptr p n)]
+                                 [byte (n) (put-u8 p n)]
+                                 [iptr (n) (put-iptr p n)]
+                                 [single (n) (put-uptr p n)]
                                  [double (high low)
-                                  (write-uptr p high)
-                                  (write-uptr p low)]))
+                                  (put-uptr p high)
+                                  (put-uptr p low)]))
                      pad-ty* fld*))))]
           [closure (offset c)
            (write-graph p t x
              (lambda ()
-               (write-byte p (constant fasl-type-closure))
-               (write-uptr p offset)
+               (put-u8 p (constant fasl-type-closure))
+               (put-uptr p offset)
                (write-fasl p t c)))]
           [flonum (high low)
            (write-graph p t x
              (lambda ()
-               (write-byte p (constant fasl-type-flonum))
-               (write-uptr p high)
-               (write-uptr p low)))]
+               (put-u8 p (constant fasl-type-flonum))
+               (put-uptr p high)
+               (put-uptr p low)))]
           [large-integer (sign vuptr)
            (write-graph p t x
              (lambda ()
-               (write-byte p (constant fasl-type-large-integer))
-               (write-byte p sign)
-               (write-uptr p (vector-length vuptr))
-               (vector-for-each (lambda (uptr) (write-uptr p uptr)) vuptr)))]
+               (put-u8 p (constant fasl-type-large-integer))
+               (put-u8 p sign)
+               (put-uptr p (vector-length vuptr))
+               (vector-for-each (lambda (uptr) (put-uptr p uptr)) vuptr)))]
           [eq-hashtable (mutable? subtype minlen veclen vpfasl)
            (write-graph p t x
              (lambda ()
-               (write-byte p (constant fasl-type-eq-hashtable))
-               (write-byte p mutable?)
-               (write-byte p subtype)
-               (write-uptr p minlen)
-               (write-uptr p veclen)
-               (write-uptr p (vector-length vpfasl))
+               (put-u8 p (constant fasl-type-eq-hashtable))
+               (put-u8 p mutable?)
+               (put-u8 p subtype)
+               (put-uptr p minlen)
+               (put-uptr p veclen)
+               (put-uptr p (vector-length vpfasl))
                (vector-for-each
                  (lambda (pfasl)
                    (write-fasl p t (car pfasl))
@@ -598,12 +609,12 @@
           [symbol-hashtable (mutable? minlen equiv veclen vpfasl)
            (write-graph p t x
              (lambda ()
-               (write-byte p (constant fasl-type-symbol-hashtable))
-               (write-byte p mutable?)
-               (write-uptr p minlen)
-               (write-byte p equiv)
-               (write-uptr p veclen)
-               (write-uptr p (vector-length vpfasl))
+               (put-u8 p (constant fasl-type-symbol-hashtable))
+               (put-u8 p mutable?)
+               (put-uptr p minlen)
+               (put-u8 p equiv)
+               (put-uptr p veclen)
+               (put-uptr p (vector-length vpfasl))
                (vector-for-each
                  (lambda (pfasl)
                    (write-fasl p t (car pfasl))
@@ -612,10 +623,10 @@
           [code (flags free name arity-mask info pinfo* bytes m vreloc)
            (write-graph p t x
              (lambda ()
-               (write-byte p (constant fasl-type-code))
-               (write-byte p flags)
-               (write-uptr p free)
-               (write-uptr p (bytevector-length bytes))
+               (put-u8 p (constant fasl-type-code))
+               (put-u8 p flags)
+               (put-uptr p free)
+               (put-uptr p (bytevector-length bytes))
                (write-fasl p t name)
                (write-fasl p t arity-mask)
                (if strip-inspector-information?
@@ -625,52 +636,28 @@
                    (write-fasl p t (fasl-atom (constant fasl-type-immediate) (constant snil)))
                    (write-fasl p t pinfo*))
                (put-bytevector p bytes)
-               (write-uptr p m)
+               (put-uptr p m)
                (vector-for-each (lambda (reloc) (write-fasl p t reloc)) vreloc)))]
           [small-integer (iptr)
-           (write-byte p (constant fasl-type-small-integer))
-           (write-iptr p iptr)]
+           (put-u8 p (constant fasl-type-small-integer))
+           (put-iptr p iptr)]
           [atom (ty uptr)
-           (write-byte p ty)
-           (write-uptr p uptr)]
+           (put-u8 p ty)
+           (put-uptr p uptr)]
           [reloc (type-etc code-offset item-offset fasl)
-           (write-byte p type-etc)
-           (write-uptr p code-offset)
-           (when (fxlogtest type-etc 2) (write-uptr p item-offset))
+           (put-u8 p type-etc)
+           (put-uptr p code-offset)
+           (when (fxlogtest type-etc 2) (put-uptr p item-offset))
            (write-fasl p t fasl)]
           [indirect (g i) (write-fasl p t (vector-ref g i))])))
 
-    (define write-byte
-      (lambda (p x)
-        (put-u8 p x)))
-
-    (define-who write-uptr
-      (lambda (p n)
-        (unless (>= n 0)
-          (sorry! "received negative input ~s" n))
-        (let f ([n n] [cbit 0])
-          (if (and (fixnum? n) (fx<= n 127))
-              (write-byte p (fxlogor n cbit))
-              (begin
-                (f (ash n -7) 128)
-                (write-byte p (fxlogor (logand n #x7f) cbit)))))))
-
-    (define write-iptr
-      (lambda (p x)
-        (let f ([n (if (< x 0) (- x) x)] [cbit 0])
-          (if (and (fixnum? n) (fx<= n 63))
-              (write-byte p (fxlogor (if (< x 0) #x80 0) (fxsll n 1) cbit))
-              (begin
-                (f (ash n -7) 1)
-                (write-byte p (fxlogor (fxsll (logand n #x7f) 1) cbit)))))))
-
     (define write-string
       (lambda (p x)
         (let ([n (string-length x)])
-          (write-uptr p n)
+          (put-uptr p n)
           (do ([i 0 (fx+ i 1)])
             ((fx= i n))
-            (write-uptr p (char->integer (string-ref x i)))))))
+            (put-uptr p (char->integer (string-ref x i)))))))
 
     (module (fasl-program-info? fasl-library/rt-info? fasl-recompile-info?)
       (import (nanopass))
@@ -700,7 +687,6 @@
             (on-reset (close-port ip)
               (let* ([script-header (read-script-header ip)]
                      [mode (and script-header (unless-feature windows (get-mode ifn)))])
-                (port-file-compressed! ip)
                 (let loop ([rentry* '()])
                   (set! fasl-count (fx+ fasl-count 1))
                   (let ([entry (read-entry ip)])
@@ -728,7 +714,6 @@
                   (on-reset (delete-file ofn #f)
                     (on-reset (close-port op)
                       (when script-header (put-bytevector op script-header))
-                      (when (compile-compressed) (port-file-compressed! op))
                       (for-each (lambda (entry) (write-entry op entry)) entry*)
                       (close-port op)
                       (unless-feature windows (when mode (chmod ofn mode)))))))))))))
@@ -898,19 +883,16 @@
                          (let ([script-header1 (read-script-header ip1)]
                                [script-header2 (read-script-header ip2)])
                            (if (equal? script-header1 script-header2)
-                               (begin
-                                 (port-file-compressed! ip1)
-                                 (port-file-compressed! ip2)
-                                 (let loop ()
-                                   (set! fasl-count (fx+ fasl-count 1))
-                                   (let ([entry1 (read-entry ip1)] [entry2 (read-entry ip2)])
-                                     (if (eof-object? entry1)
-                                         (or (eof-object? entry2)
-                                             (and error? (bogus "~a has fewer fasl entries than ~a" ifn1 ifn2)))
-                                         (if (eof-object? entry2)
-                                             (and error? (bogus "~a has fewer fasl entries than ~a" ifn2 ifn1))
-                                             (and (fluid-let ([cmp-ht (make-eq-hashtable)]
-                                                              [gensym-table (make-hashtable string-hash string=?)])
-                                                    (fasl=? entry1 entry2))
-                                                  (loop)))))))
+                               (let loop ()
+                                 (set! fasl-count (fx+ fasl-count 1))
+                                 (let ([entry1 (read-entry ip1)] [entry2 (read-entry ip2)])
+                                   (if (eof-object? entry1)
+                                       (or (eof-object? entry2)
+                                           (and error? (bogus "~a has fewer fasl entries than ~a" ifn1 ifn2)))
+                                       (if (eof-object? entry2)
+                                           (and error? (bogus "~a has fewer fasl entries than ~a" ifn2 ifn1))
+                                           (and (fluid-let ([cmp-ht (make-eq-hashtable)]
+                                                            [gensym-table (make-hashtable string-hash string=?)])
+                                                  (fasl=? entry1 entry2))
+                                                (loop))))))
                                (and error? (bogus "script headers ~s and ~s differ" script-header1 script-header2)))))))))))])))))
diff --git a/s/strnum.ss b/s/strnum.ss
index 5a3f74f168..6ad3ccc481 100644
--- a/s/strnum.ss
+++ b/s/strnum.ss
@@ -1,4 +1,3 @@
-"strnum.ss"
 ;;; strnum.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -94,6 +93,7 @@ restriction, with string->number returning #f and the reader raising
 an exception.
 |#
 
+(begin
 (let ()
 ;;   (mknum-state <state name>
 ;;                <expression if end of string found>
@@ -542,3 +542,4 @@ an exception.
      (unless (inexact? x)
        ($oops who "a precision is specified and ~s is not inexact" x))
      (parameterize ([print-radix r] [print-precision m]) (format "~a" x))]))
+)
diff --git a/s/syntax.ss b/s/syntax.ss
index 425f30410b..792a452263 100644
--- a/s/syntax.ss
+++ b/s/syntax.ss
@@ -1,4 +1,3 @@
-"syntax.ss"
 ;;; syntax.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;; 
@@ -4867,7 +4866,6 @@
                                           fp
                                           (loop fp))))))
                             (begin (set-port-position! ip start-pos) 0)))])
-              (port-file-compressed! ip)
               (if ($compiled-file-header? ip)
                   (let ([x (fasl-read ip)])
                     (close-port ip)
@@ -5210,7 +5208,6 @@
                                             fp
                                             (loop fp))))))
                               (begin (set-port-position! ip start-pos) 0)))])
-                (port-file-compressed! ip)
                 (unless ($compiled-file-header? ip) ($oops who "missing header for compiled file ~s" fn))
                 (let ([x (fasl-read ip)])
                   (unless (recompile-info? x) ($oops who "expected recompile info at start of ~s, found ~a" fn x)))
@@ -7510,6 +7507,7 @@
 
 (current-expand sc-expand)
 
+(begin
 ;;; syntax-rules/syntax-case aux keywords
 (define-syntax ...
   (lambda (x)
@@ -10344,3 +10342,4 @@
 
 (set-who! $annotation-options (make-enumeration '(debug profile)))
 (set-who! $make-annotation-options (enum-set-constructor $annotation-options))
+)
diff --git a/s/trace.ss b/s/trace.ss
index 31f1248ddb..49f84eba91 100644
--- a/s/trace.ss
+++ b/s/trace.ss
@@ -1,4 +1,3 @@
-"trace.ss"
 ;;; trace.ss
 ;;; Copyright 1984-2017 Cisco Systems, Inc.
 ;;;