Sinclair ZX80 / ZX81 / Z88 Forums

Thanks Moggy :) As nobody else seems to be doing it, I'm considering supplying sets of the decals via sellmyretro in case other people want to finish off their ZX80 in the same way. decal-set.jpg Take my money! I had a bit of a retro-brighting mishap with the main ZX80 logo on my later moulded mode...

Yes, it's nice to have my main Speccy going again with perfect picture etc. I even oiled the tape mech, it's not perfect but loads and saves well. I like the grey +2 because: 1. They're cheap compared to the original 128k. 2. Microdrive compatibility (unlike all the later versions). 3. Cassette deck...

Fixed! It totally was the 40058. It now has the PCF1306P fitted... which is of course even older than the original, but that's fine, there's a socket in case that dies.

The multiplexer for all the DRAM chips is IC10 (which goes by one of these part numbers depending on when it was made: PCF1306P, ZX8401, 40058). Mark Aha. I do actually have a broken issue 6A 48k board that had an issue and I've been using as spares. It has it's PCF1306P present, but obviously I do...

With my 'scope out I had a look at the ram address lines. The top row (IC17 - 24) all have nice square activity (the top row in the pic below). The bottom row (IC25 - 32) shows weirdness, not proper square waves and some that peak in the middle somewhere, neither high nor low (bottom line in the pic...

I just tried the Brendan Alford diagnostic ROM and the screen is illegible and then there are all 8 red bars in the border. Deary me.

Can you burn EPROM chips? Mark Yes. You think it's the ROM? Or you mean to burn a diagnostic ROM? I do actually have the original saved ROM data somewhere. I have the plug in DiagRom and that is obviously more focussed on 48k models but I did manage to get through to the 128k menu and it reported a...

I swapped all the RAM (fortunately I'd socketed it all a while ago as this is my main tinkering Spectrum) and that changed nothing. I checked all the original RAM in another Spectrum and it seemed fine. When I start it I get variations of this: 20201122_172121_resized.jpg Sometimes there are a lot o...

Well it certainly fixed the screen using an original PSU for now, but I seem to have done some damage to something else now as I get random patterns and junk on the (perfect) screen! Going to have to investigate.

No, not actually dumping them in the bin, but dumping the contents of them properly, i.e. sector by sector to make an exact duplicate of the original.... I have a vDrive ZX which is probably the most convenient way of copying data from original mdvs to an SD card (and then to a modern computer) but ...