80-Bus News

The Defence

Space Invader

Changing all locations marked equal to each other for the same character is essential.

Reading 80-BUS News issue 1 regarding changing over the ‘line feed’ and ‘newline’ keys, I made an attempt to do this under software control, the following being the result. N.B. EPROM blower is essential.

Change Nas-Sys 1 location 05A8 to 89, 05AB to 0F, 0585 to 09 and 05B9 to 8E and swap over the keytops for L.F. and Newline.

One problem, ESCape works OK in machine code routines, however to escape from BASIC (usually shift and newline twice) requires shift L.F. followed by shift newline. I cannot find the reason, I suspect something in the BASIC chip. Has anyone the answer? [Ed. – Yep, the BASIC ROM does shortened keyboard scans directly whilst RUNning programs, and is looking for the specific key depressions that correspond with the original shift and newline key positions.]

While in the Nas-Sys EPROM why not change locations 03BC to 03C4 (Nas-Sys 1 message) to your own, my own displays MIKES m/c, a very personal message. Location 0077, normally 5F, is the cursor blink character, changing to B6 will give you the little man.

Going back to messages, I have a second EPROM with software for the IVC from Gemini which I fitted at 0494 (load command for paper tapes). If you want a longer message than the 8 available at 03BC then put a jump to 0494 from 03BC and put your message from 0494. (The software at 0494 is my own and not from Gemini.)

Lastly, still in Nas-Sys, I changed location 07BE to 00B0 which gives me my Bits and PCs toolkit by simply typing D on the keyboard and newline.

Mike Trim, Ashton in Makerfield.

MONITOR, Naspen & Reset

As a relatively new convert to the 80-BUS and the associated products I have a lot to learn and I am greatly indebted to your magazine and its two predecessors for their assistance in my learning process. May I take this opportunity of wishing the new title a long and successful publication run.

My learning curve has now extended far enough that I am in a position to make some rather hesitant contributions to the store of knowledge that I have so far drawn on so heavily.

MONITOR.COM AGAIN

I rather regret that I did not receive my back copies of Micropower, that other magazine, including Chris Blackmore’s article on MONITOR.COM until after I had devised my own solution to the problem. However, your readers may be interested in a different approach. I dis-assembled Nas-Sys 3 using NAS-DIS, identified the references to VRAM and the work space from the published listing, and then re-compiled the resulting source code with a revised origin at 100H, VRAM set to F800H and the work space unchanged at 0C00H. Locations 100 – 102H were changed to a jump to new code at 900H – 0BFFH which writes appropriate jumps into the Restart locations, adds support for an EPSON Printer and adds disk routines. One advantage