Sinclair ZX80 / ZX81 / Z88 Forums

Hi!

If I'm creating a new circuit to connect to the ZX81 is it possible to:

1. Pull the WAIT signal LOW
2. Update the RAM of the ZX81
3. Release the WAIT signal

and then the RAM is updated by the external circuit.

Is that possible?

Maybe this topic should be moved to the Spectrum section.

I believe using the SD-Formatter program to format your card before usage is a good idea. I believe there is also an issue that firmware cannot be updated from a large SD-card. I think the firmware update might only work on a SD card formatted with FAT16. I cannot remember. I just know I have an old...

I have one of these, that with an electro magnet suck once, and when you release the button, blows all solder out again. So it's not very good. However it's better than none at all.

https://a.co/d/hodRSQB

You have conflict in the address space. I'm not an electronics expert, but I believe two different signal is comming to the bus at the same time, which makes it a coincident who is winning the signal competition. At best the Zeddy wont work. At worst you destoy one of the chips. Anyone please correc...

That's a good resource you've gathered. Maybe you should add a link to it in your signature. You can simply add a signature to all your post in you profile here at the forum. This would make it easy for us to find the link, because we just need to find one of your posts.

We also have a Spectrum section on this forum. Feel free to ask there.

That's a brilliant job. And it looks gorgeous with the expensive keycaps.

I've received your book with 81 games for Christmas. I believe you also worked on a book with programming examples for 1k games. Has that been released as a physical book yet?

So you have changed the famale jack on the board to a 3 signal connector?