80-Bus News

NAS­COM(?) 1.5(?)

Finally a letter from Steve Waites which I reproduce below:

“Back in the dark annals of history I had a perfectly good and working Nascom 1 + RAM A card. Simple but effective. Then I left to work in America so the poor old computer got left behind. Two years later I returned, and found that the old Nascom had pined itself away to an early demise. Checking the boards I found several of the 2102 RAMs and a few TTL chips had gone to the great semiconductor heaven. In desperation, and because I only had two weeks in England, I grabbed all the relavent software and made the decision to rebuild and upgrade. Several months of hard effort later I now welcome the Nascom 1.5. Why 1.5? Well its no longer a Nascom 1, nor is it quite a Nascom 2. My additions are an enhanced RS232 port, 18K of CMOS RAM on the main board plus 4118 RAMs for the video and user areas. Oh yes it also has a sound chip, a battery backed RAM area, graphics, and the memory is fully decoded in 2K blocks by a 74LS154.

“So far so good – everything works wonderfully – now to my question. Is there anyway that I can get my ZEAP (level 2.1 in ROM) to output continuously to the UART port as I usually use my computer with a slave CRT connected to the RS232 interface rather than the internal video. Also, but not quite so important, I have the Bits & PCs programmers toolkit. It won’t accept commands from the remote CRT keyboard. Both Nas-Sys and BASIC have no problems in this respect, so what is the difference?”

Perhaps some of you ZEAP hackers can write in with a solution for Steve. I believe that ZEAP writes directly into the bottom line of the NAS­COM display. This is done for speed, as outputing a character at a time via Nas-Sys would have an impact on the already slow assembly speed of ZEAP. How much of ZEAP’s output goes this way I have no idea. As for the Bits & PCs toolkit, this uses its own input and output tables, and also utilises UIN and UOUT. I assume that a small error must exist in this somewhere which prevents it scanning the serial input port. Perhaps some enterprising person who is using the toolkit can send in a suitable patch that can be published in a subsequent issue of the NEWS?

Ta Ta.

References:

1. HART J.F, CHENEY E.W. et al,“Computer Approximations”, Pub: John Wiley 1978
2. SCHMID H., “Decimal Computation”, Pub: John Wiley 1974
3. MYERS G.J., “The Art of Software Testing”, Pub: John Wiley 1979.
4. BRUCE R.C., “Software debugging for Microcomputers”, Reston Publ. Co. 1980

Arfon Speech Board – #50. 16K RAM A board – #15. 32K RAM B board – #40. Easicomp PSG board (minus AY-3-8910 chip) – #10. Machine Code Programming for the Nascom Book – #2. Phone Kevin on ____-_____ (evenings).

IBM Selectric KBD printer, ex. 2741, with hardware/​sofware interface for Nascom & Nas-Sys. Uses 8 bits of PIO. Previously IBM maintained, in excellent working order. Sensible offers please to Ian on Ipswich (____) ______.