#USE "course"

PROC main (CHAN OF BYTE in, out)
  BOOL running:
  SEQ
    running := TRUE
    WHILE running
      BYTE b:
      SEQ
        in ? b
        IF
          b = 27 -- ESC
            running := FALSE
          (b >= 'a') AND (b <= 'z')
            out ! b - ('a' - 'A')
          TRUE
            out ! b
        out ! FLUSH
: