Sinclair ZX80 / ZX81 / Z88 Forums

Yes, at the time I started this thread the timing crystal leg was bent and was touching the resistor leg next to it. Currently no component is touching any other.

Well it wasn't the SRAM. I guess I need a ULA then (which was the problem all along, so nothing lost).

1024MAK wrote: ↑Fri Oct 01, 2021 7:21 pm You could continuity test each ULA pin (on the pin of the chip) to another node that the PCB track goes to.

I did that, but nothing unusual to report.

Thanks, I'll give that a go. I think there's a chance the ULA might live on, since I only had it powered for a few seconds in the wrong orientation. Not enough time to heat up. This board was hanging around for months and may have been handled a bit while its ULA was out. So unfortunately it's not a...

May we have a moment of silence for the dead ULA... :cry: Ah well it was damaged anyway. It wouldn't load from EAR, whether using a TZXDuino or a WESPI (which work fine with my other Zeddy) and I tested the components leading from that input to the ULA. Even tried some other ratings for the capacit...

This ZX81 has a non-working EAR port which appears to be down to the ULA. I carefully desoldered the ULA (I've done a Z80 successfully on a Spectrum before now) and socketed it. Just now I stupidly managed to insert it upside down in its socket and powered it on. With the ULA back in the correct ori...

Lardo Boffin wrote: ↑Sat Sep 04, 2021 5:04 pm Rookie numbers

Moggy wrote: ↑Sat Sep 04, 2021 6:29 pm If the ZX8-CCB becomes available...

Anyone know whether these may reappear? I've put myself on the notification list on sellmyretro, but is there any chance Pokemon might sell them within Europe?

I have gone over the photos and double checked. You are correct that A17 and A18 are mixed up for the SRAM connection but, as Paul has mentioned, this has no functional impact. I do however label A17 & A18 consistently with their actual positions on the motherboard near the card connector. Consequen...

The OZ 5.0 roms get compiled automatically every time there's a commit I think (continuous integration), which is why there are so many. Use the most recent, but be cautious if the recent commit history indicates changes to the flash memory code. OZ 5.0 is going to hit beta status soon apparently. L...

working.jpg A quick test to make sure the patient survived the procedure! reassembled.jpg Fully re-assembled. OZ5.jpg And after testing for a week or so running OZ 5.0 from Slot 1, I decided to take the plunge and update my internal flash (Slot 0) to OZ 5.0 via the <>UPD command in Index. It comple...

Owning a Rakewell flashcard for your Z88 is recommended, but it's a pain when most of its capacity immediately has to be used for the operating system upgrade to run OZ 4.7.1, or indeed the new version 5.0. You can get around this by replacing the 128K internal ROM chip with a 512K flash memory chip...