Sinclair ZX80 / ZX81 / Z88 Forums

I have a Chinese EPROM programmer and before I started putting the sockets/resistors/caps etc on the board I thought I should probably check all the chips as their age and source was unknown (I wasn't bothered about the Z80 as I have some known good spares of those). I was able to use the same progr...

I bet the EPROM is empty for a start! With mine I also got a couple of wrong 74XX chips, so also check those are all correct.

Oh yes, I have those alternate EPROM connections on mine too, never noticed that! Well, in that case, that looks ok.

Here we are. Back is marked with the transistor positions (both are BC239C) and C for capacitor, R for resistor.

Any idea why the circuit is broken where those two wires come out next to that resistor at the bottom?

Yes of course. I would have removed it all, but it looks like I'll have to remove the switches and 5v socket to get the board out. The CR-TB switch just choses between 2 different resistors and neither position seems to make contact so I'll take everything out and clean it all up.

Hello, I got this homemade device with a selection of ZX81 bits and pieces a couple of months ago. It's clearly designed to go between the ZX81 and the cassette recorder. I'd be interested to know more about what it may actually do though, from those that understand these things! It appears to requi...

There's still a German language one, that is apparently also available in English (or is bi-lingual, I'm not sure) and comes with a 3.5in Disk on the cover. I subscribed a couple of weeks ago, so will report back when I get one. It's Speccy-scene.de (not the most modern or informative website, but y...

I can't speak for the OP, but I got mine on ebay from a Russian (who seemed to have Chinese connections). It seems very well made and as far as I can tell, it's (in terms of traces) an exact copy of an original. Here are some pics. It came with all the IC's and crystal, most of which look 2nd hand -...

I have one of these but haven't finished it yet. Is that just a plain socket under the ROM? Are you sure the ROM is right? The kit that I got included a ROM chip (2732) but there was no data on it. I have a 2732 to 2532 adapter for when I make mine.

Thanks so much for that insight, both of you. I feel I've learnt something again, something very basic, but it has clicked (I think) and is my mini revelation for today. Those pokes, which end up at the beginning of the REM statement, due to them being at addresses 16514 onwards, are assembly langua...

Thanks very much Paul and Mark. I'll convert the .p to a wav, load it, make the changes and see how I get on.