Non Stop Basic

by Chris Fox


Issue 28

Jul/Aug 87


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Prevent your BASIC programs from being listed or stopped with this simple routine


How often have you written a BASIC program that you want to protect from accidental BREAKs or SYSTEM RESETs? Perhaps you want to prevent others from seeing the listing or simply want to make your program look more professional? Worry no more, for NON STOP BASIC will do just this for you.

The program is quite simple. It stores a machine code routine at location $100 (thus leaving Page 6 free for other programs) and simply disables the Break key and uses IOCB # to print' RUN' on the screen,' RETURN' it, and pass control back to BASIC. The SYSTEM RESET key is vectored to the program through CASINI so your own BASIC program will be run from the RESET key.


There are a few problems you may run into with NON STOP. Firstly any BASIC errors will stop the program so all errors must be properly trapped. Secondly, any statement which opens the Editor (e.g. Graphics calls) normally re-enables the Break key. NON STOP handles this by using a stage 1 VBI to constantly disable the Break key but if you use your own VBI you may have problems. If you do use a Stage 1 VBI, change line 32050 to a REM and ensure that your VBI routine disables the Break key. This can be done by adding the following instructions to your routine.

LDA $10


ORA #40

STA $10

Finally some programs 'ERROR' or crash when run a second time. If you can't identify and alleviate this problem, then I am afraid that you won't be able to use NON STOP properly.


Simplicity itself! Just type in the listing and LIST it to disk or cassette. Load, or write, your program and ENTER the NON STOP listing. Change the first line of your program to GOSUB 32000 and you are away!

Now when you write a program to keep the kids quiet, they will have to play it and not mess around with your code!


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