Issue 1 board

Discussions about Sinclair ZX80 and ZX81 Hardware
Post Reply
poglad
Posts: 133
Joined: Mon Mar 24, 2014 3:11 pm
Location: Aberdeen, Scotland

Issue 1 board

Post by poglad »

Hi all,

I and someone else (maybe someone here?) managed to secure a ZX81 issue 1 motherboard each from eBay last night, for about a tenner apiece. Nice! Sold as tested and working, but in the photo it looks a real mess. I think they were built from kits. I'll post some pics when it arrives, and you can all let me know if I've been sold a dud! :)

My own original ZX81 is down in England at the moment. I'm not sure what issue it is, but I went through 2 or 3 replacements during the guarantee period so the one I ended up with may have been one of the final issues. That final replacement was at the end of 1983. Anyway, it's certainly not an issue 1, so I've expanded my collection a little.
User avatar
1024MAK
Posts: 5101
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Issue 1 board

Post by 1024MAK »

If it's not an issue 1, then if it is a UK ZX81, it must be an issue 3. As no issue 2 boards have been found.

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
Looking forward to summer later in the year.
poglad
Posts: 133
Joined: Mon Mar 24, 2014 3:11 pm
Location: Aberdeen, Scotland

Re: Issue 1 board

Post by poglad »

I'm 99% sure that's what it is. But you never know, with Sinclair's habit of fixing returns and reselling them. So I won't know for certain until I get my hands on it again! :lol:
Moggy
Posts: 3231
Joined: Wed Jun 18, 2008 2:00 pm

Re: Issue 1 board

Post by Moggy »

I saw those two boards and one of them had the later ULA fitted. The type face on that ULA was slightly different to the norm IE big bright and bold covering nearly the whole of the chip, a bit of a rarity perhaps?
Last edited by Moggy on Thu Jul 03, 2014 9:40 pm, edited 1 time in total.
poglad
Posts: 133
Joined: Mon Mar 24, 2014 3:11 pm
Location: Aberdeen, Scotland

Re: Issue 1 board

Post by poglad »

They looked to me like the owner had swapped chips back and forth perhaps... so either a rarity or an anachronism lol. But the chips look to be socketed, so it shouldn't be hard to improve the authenticity of it in future if appropriate.
Post Reply