OK. This is the very computer that started it all for me.
As you can see, it isn’t in original condition. There are a few mods and, unfortunately, the processor is missing! I think I put it in someone’s ZX81 some years ago. I’m sure I have another somewhere under all this junk…
Note that I never did build the RF modulator shown on the circuit diagram. After the first batch or so of machines were produced NASCOM started to include a ready-built, screened Astec unit which is fitted to the underside of my PCB.
 Main circuit diagram |
 Keyboard circuit diagram |
 Video circuit diagram |
This computer came fitted with the Nasbug 1.T2 monitor software, which I upgraded pretty quickly! I say “fitted”, but that’s in the broadest sense as the whole thing came as a kit. The keyboard and RF modulator were pre-built but that’s all. The kit came with two books. They became known as “the easy book” and “the hard book” – the construction manual being considered “easy” at that time!
The keyboard was rather unusual by today’s standards – and not at all easy to work with as it was driven and decoded by routines in the monitor. The keys were of the Licon magnetic transformer type. These are completely contactless. Because of the way in which this type of keyboard works it is completely free of contact “bounce”. The reset key is a standard switch type. I’ve gone into much more detail on the keyboard Here.
The “hard” book!
If any reader remembers a book called “The Cheap Video Cookbook” by Don Lancaster, it is instructive to compare the Nascom 1 video circuit with one of the schematics in that book. If I remember correctly they were both based on a system originally described (by Don?) in Wireless World.
The Nascom-1 was designed with little capability for expansion. A single-sided card edge connector at one end brought out various signals, but they were not buffered so were incapable of driving address and data bus signals to many external devices. In addition, there was a problem with the processor clock at the edge connector, which caused timing problems. That is where the Buffer Board came in. This was an 8″ square card which interfaced the Nascom-1 edge connector to a versatile 80-way bus system – the same one which was later native to the Nascom-2.
Andrew has provided me with this rather nice PDF of a Henry’s Radio brochure. I find it particularly interesting because it includes prices for the various bits of Nascom-1 kit. Nascom Brochure Oct 1978. The cost of a basic Nascom-1 (£197.50) would be about £1040 today. We spent a lot of money on this stuff.
Well, how exciting can you get? A Nascom-1 kit ready to dive into.
The contents of the box are revealed. Then it’s just a bit of soldering to go…. 🙂
Apparently there was a bit of a problem at the design stage. The PCB design was sub-contracted to an Irish company who were using an early PCB CAD package to lay the board out. Unfortunately, the process was time consuming and costly. When the design came through it was found to be unnecessarily large and it was too expensive to change.
nascom.info 
Ah, happy days! Thanks for jolting my memory of my first computer. I spent many happy hours building and “improving” my Nascom 1, eventually expanding the memory to 48k and adding an Ikon tape drive in place of the cassette.
What an excellent write up on NASCOM, lots of good information, thank you. I currently own a NASCOM 1 with NasBug.T4 fitted in excellent working condition. I housed it a Dragon 32 case utilising the Dragon power supply..