1 'Copyright 1998 The American Cryptogram Association (ACA)
2 'One Pidgeon Drive, Wilbraham MA 01095-2604
3 'All rights reserved.

496 DEF FNSC$ = CHR$(SCREEN(PR,PC))

716   IF K1$ <> " " THEN 720
717   GOSUB 6000 'Do x'ing out
718   GOTO 760

6000 '=== Space Bar: X-out cell ===
6010 XC$ = FNSC$  'Read screen cell
6020 XS$ = "x" : XO$ = ""
6030 IF XC$ = " " THEN XO$ = XS$
6040 IF XC$ = XS$ THEN XO$ = " "
6050 IF XO$ = "" THEN 6099
6055 FOR L1 = 1 TO 4 'Rotate x-out
6060   PRINT XO$;    'thru 4 lines
6065   C = FNGC(FNGR(FNCG(C)))
6070   R=R+RI: IF R>RE THEN R=RB
6075   GOSUB 800 'Move cursor to R,C
6080 NEXT L1
6099 RETURN

FUNCTION IofC(Txt$)
  Dim Freq(127)
  N=Len(Txt$)
  For I=1 To N
    L=Asc(Mid$(Txt$,I,1))
    Freq(L)=Freq(L)+1
  Next I
  For I=32 TO 127
    F=Freq(I)
    If F>1 Then Sum=Sum+(F*(F-1))
  Next I
  IofC=Sum/(N*(N-1))
END FUNCTION