HACKER BASHER One of our most frequent requests is for ways of making your programs hacker proof (personally I feel pleased that anybody would want to see how I wrote a program). I.J. Rogers has sent us the method he uses. One method is to make a program unmergeable and this can be done by POKING the line length of the first line in the program with 255. When the program is saved and someone tries to MERGE it the computer thinks it hasn't enough memory and refuses to accept it! Due to the way in which Sinclair BASIC is stored you have to add a little more to your program than a simple POKE, but this isn't a lot and it is very easy. The secret is to include the following lines: 1 POKE 23758,0: GO TO 5 5 main program starts here 9999 POKE 23758,255: SAVE "PROGRAM" LINE 1 SAVE your program by using the instruction GO TO 9999 and verify it with VERIFY "" as per usual. Now NEW your computer and try to MERGE the program. Mind you it is not much use on its own as you can still load it and BREAK the program to list it. To make it completely foolproof you will have to use one of the POKEs which cause a crash if anyone tries to break it as the first line of your program. i.e. 5 POKE 65364,0: POKE 65365,0 [This is assuming that RAMTOP is at the default location of 65367. JimG] And, just to make life really difficult, you may have to use a bit of extra code to find the start of the BASIC line if you have a microdrive or disk unit attached; i.e. POKE (PEEK 23635+256*PEEK 23636)+3, 255 or 0