Christmas 1979, Issue 5

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A few things to note; the subroutine starts at 0C60; if you have a Bits & PC’s graphics board, put E0 at 0C62. You can also load register C with the character of your choice and call 0C6D. Fun, isn’t it? (It seems to impress non-computer owners, too). Keen users of disassemblers will find some very interesting instructions mixed in with the well-known ones.

I must have been typing E 0C50NL for over a year now, and nobody told me that the E command will’ pick up three addresses, if they are there, If you type E 0C50 0C60 0C70 the program at 0C50 will be executed as normal, but all three “addresses are in the scratchpad RAM, available for use by the program. The 0C60 would be at ARG 2 (0C0E/F) and 0C70 at ARG 3 (0C10/1). This would be useful if you had a program you wanted to run repeatedly, with varying parameters, and couldn’t be bothered to put a proper keyboard input routine in, or hadn’t enough memory to do so.


The first edition of the Liverpool Software Gazette has arrived at Zilog Villas; it is produced by Microdigital, and is well worth investigation. For a start, they have included a listing of their own Nascom programming language, M5. This is normally sold for ten pounds, so you save nine pounds fifty on the first issue! There is also an article about running Sargon on a Nascom, which I expect will come in handy when I get around to translating all those funny TDL mnemonics. There was also a short article on the text oriented language, Pilot, which has given me an idea for what to write next to perplex poor Marvin. Obviously, a Nascom Pilot interpreter.... Yet another setback for the heap of half finished programs in my possession. (An example of this is the program suggested by Richard Beal, to test/​convert programs intended for other machines; to tell the truth though, all I had done was draw a circle and write “start” in it....)


The code that follows is used to draw a maze on the screen, the computer then has to try to solve the maze. The target is represented by a @ and the creature that has to solve the maze by a symbol I can’t type – 07H. You know the one I mean…​Key U,​D,​L or R to draw the maze, E to erase parts you don’t want, F to mark the finish, and then S to start. The next instruction will be at 0CB0, only you have to write it.

0CB0 Your turn.....

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