ZX21 Project ZX81 Replacement PCB

[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]

[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.

[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

[XavSnap]

Kicad Project:

[fordp2002]

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.

[fordp2002]

I am still missing some bits.

[1024MAK]

Still, it’s coming along

Mark

[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.

[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.

[fordp2002]

Massive progress, it somewhat works.
Some keys on the keyboard are not working yet.