Atari Unlist

I own an Atari 800 and have been trying to prevent people from LISTing my BASIC programs. Is it possible to do this?

John A. Butera

Ian Chadwick provides an interesting solution to this problem in his book Mapping the Atari, available from COMPUTE! Books. First, save a copy of your original program (this is very important because the scrambled version of the program will be almost impossible to restore). Then add these two lines to the program, replacing FILENAME with the filename you wish the scrambled version to have.

32000 FOR VARI = PEEK (130) + PEEK (131) * 256 TO PEEK (132)
   + PEEK (133) * 256 : POKE VARI, 155 : NEXT VARI
32100 POKE PEEK (138) + PEEK (139) * 256 + 2, 0 :
   SAVE "D : FILENAME" : NEW

Type CLR:GOTO 32000 in immediate mode and press RETURN. Line 32000 replaces all the program's variables with carriage returns and line 32100 saves the program to disk. This version of the program can't be LISTed or even LOADed. The only way to run it is with the command RUN "D:PROG" (substitute the name of your program for PROG).