Sinclair ZX80 / ZX81 / Z88 Forums

There are w27c512 eeproms with EPROM pinout that I often recommend. These can often be reprogrammed and about the waste: It's the question of price per piece and not 8k against 64k. If you only want to replace the original I advise to fill the 64k with 8 times the 8k. This way it doesn't matter at w...

There are 7 inch vga displays that are suitable

This is the display driver device name.
There are several display with various sizes available.
Make sure it's 320x240.
I have a 3.2 inch which is very readable and a joy to work with. I saw 3.5 inch, but not at a reasonable price.

I remember it well.

Thanks for the update. Charlie already told me some weeks ago.
Please keep in touch.
And good luck for your personal circumstances.
Cheers
Paul

Retronaut wrote: ↑Thu Jan 25, 2024 12:11 pm Don't get me wrong, the ZX80/81 were vital stepping stones, but they were certainly NOT mass market.

This may be true for the ZX80 but ZX81 sold about 2 Million at what number do you think mass market starts?

That's not what /wait is intended for. I don't know what happens to all the other z80 control lines. If you try a /busreq and wait for busack then z80 goes into tristate and you can acces the ram in any way you like for as long as you like. Of course the screen will not be updated by the zeddy. That...

The ZX81 capacitor are not known to leak but they dry out.
They are unimportant so nothing breaks if they fail.

The 1uF only needs replacing if you have a zeddy that needs more than a single try to start properly.

I have something like the first link you provided. But I never needed it. I also have the zd915 and use the following steps: First I apply flux gel Next I desolder every pin. Not from the top but horizontal. This way I can see what I'm doing and it's not necessary to work against gravity. After ever...