Sinclair ZX80 / ZX81 / Z88 Forums

To be fair Michelle I've never known the original ULAs to just give up or even fail due to the much vaunted yet unproven myth of "heat damage" , rather they bite the bullet due to human intervention such as plug/unplugging an interface when the Zeddy is powered up, shorting them out whilst working ...

The ULA is, unfortunately, the most common thing to die, at least partially. Mark also thinks it's likely what's failed in yours. vRetro sells modern replacements - https://www.vretrodesign.com/products/vla81-zx81-ula-replacement If you're in the UK they are available here - https://www.retrorevival...

I put a spreadsheet together of the pin outs/responses that people advised should be. It's on the page here - https://msknight.com/bbc/zx81-logictest.html - in Open Doc format. That might help.

Do you have any chips to swap out and test with?

Thanks. Looks like I'm in for an entertaining time doing the whole board

Just a quick update on what's happening here. Of six zeddy's... *) One was ported to a new case containing a Pi and mechanical keyboard. Was a bit of a butcher job, but it works. *) One is waiting for a wood case. Just want to get the others out of the way first. It has a ZXpand+ and waiting for joy...

I'm not sure. Is it that watch attachment thing? https://www.google.co.uk/search?sca_esv=d2fbde582ddfbd7f&q=Data+2000+computer&uds=ADvngMgoxBifNZSFCILBf-jevBfUb4LV-OnNANPHIc6V4Ihqm2gr0fTlM-Pp9foDFyRMAmFWaISwAeVU9szNYvFnx3t_Ijehb_dXimIdCPJHRkZgqp9TBrwLJQWxIwVbrNhG0X9ph7PV3DuYfHyuRpUJZQqbfQ_05y_o4AS8D...

I don't know if there is anything pre-made. If there was, it would probably be an individual doing it... so in that sense it is possible. However, I'd encourage you do pick up the soldering iron and give it a go. HDMI isn't straightforward, however. My experience and costing to build a new mechanica...

Cheers. Got some on order. Wonder if I've wrecked the thing ... oh the joys of not knowing

Thanks. I'll look that up.

The sockets are turned pin, so don't accept square pin headers.