Page 4 of 7
Re: ZX21 Project ZX81 Replacement PCB
Posted: Fri Dec 18, 2020 7:33 pm
by blittled
Can't wait to see how it works!
. I'm going to start looking into replacement ULAs. I don't want to cannibalize the ZX81s I have to build another one. I know this will be opensource so it'll be up to me to find a pcb fab house and send the gerbers to them.... unless someone makes a run of pcbs and sells them. [Hint]
Re: ZX21 Project ZX81 Replacement PCB
Posted: Fri Dec 18, 2020 10:48 pm
by fordp2002
I am looking forward to getting it going. I may have some spare PCBs when I have finished. It is called the ZX21 for a reason I am not expecting to have it finished this year but I am hopeful for next year.
Re: ZX21 Project ZX81 Replacement PCB
Posted: Sat Dec 19, 2020 1:14 am
by 1024MAK
Which bright spark is gonna point out that there are less than twelve tinkering days to the new year, ahh, that would be me then
If there are any spare PCBs, I would like one please.
Mark
Re: ZX21 Project ZX81 Replacement PCB
Posted: Sat Dec 19, 2020 5:07 pm
by XavSnap
Re: ZX21 Project ZX81 Replacement PCB
Posted: Sat Dec 19, 2020 6:16 pm
by fordp2002
XavSnap wrote: ↑Sat Dec 19, 2020 5:07 pm
Kicad Project:
Thanks for the screenshots.
When I get time I want to get the 3D models right on most of the parts. I hope if anybody else has ideas they can start making use of the ZX21 project.
Re: ZX21 Project ZX81 Replacement PCB
Posted: Sun Dec 20, 2020 5:22 pm
by fordp2002
I am still missing some bits.
Re: ZX21 Project ZX81 Replacement PCB
Posted: Sun Dec 20, 2020 6:52 pm
by 1024MAK
Still, it’s coming along
Mark
Re: ZX21 Project ZX81 Replacement PCB
Posted: Sun Dec 20, 2020 8:14 pm
by fordp2002
I have added quite a few more bits since that picture and I have ordered the remaining passives from Farnell. £50 but I have ordered plenty for projects for a few years (of those values).
Oh and I spotted in time I had two RAM chips and no ROM chip above, Doh.
Re: ZX21 Project ZX81 Replacement PCB
Posted: Thu Dec 24, 2020 4:15 pm
by fordp2002
All the bits for a standard ZX81 are now it fitted. It is powered on and the clock is ticking.
On to troubleshooting now.
Re: ZX21 Project ZX81 Replacement PCB
Posted: Thu Dec 24, 2020 4:45 pm
by fordp2002
Massive progress, it somewhat works.
Some keys on the keyboard are not working yet.