Sinclair ZX80 / ZX81 / Z88 Forums

Moggy wrote: ↑Thu Mar 14, 2024 2:28 pm I'm fairly certain I have a Kempston interface for the 81 somewhere, which I acquired in a job lot. I have no use for it so if I can dig it out you are more than welcome to it.

Thanks very much. No rush, give me a nudge as and when and we'll sort out postage.

Thanks. Anything you could find would be much appreciated.

I'm currently trying to find the PCB for a Spectrum Kempston joystick but I'm having problems interpreting the German. Have downloaded a copy of LibrePCB in the hope that I can learn enough to alter someone elses PCB layout.

I've been reading a few things, and some conversations that were had in 2017 about nuclear power station control.... but hey ho. As I have a number of zeddys in different configurations and I'm not keen on swapping the ZXpand+ constantly on edge connectors, I was wondering if there is a modern Atari...

Cheers! Many thanks for the info. Much appreciated.

I've been running some classic 3D Monster Maze and with the Big Bang ROM it seems a bit quicker and more fun to play. However, I was wondering about the ZXpand+ ROM and whether it is more like the Big Bang, or more like 649 please. I know that I can fit a zeddy with a big bang and execute the X opti...

1024MAK wrote: ↑Sun Mar 10, 2024 11:01 am People are following the details that are widely available on the internet, even though those details are slightly misleading.

Mark

That's one reason why I'm asking the silly, awkward questions... in the hope of getting my own details slightly less misleading than everyone elses

Ah! That explains it. The resistor is present on the myretrostore 16k upgrade, so I wonder why they put it in. They also have an extra capacitor in there as well. I'm not sure why.

I think you have bunked why "some" ZX81s did not work with my hiresgames. We wanted to release a tape with all games but due to this issue we never did. Cheers. That explains it. I've noted this down on the ULAs and will put them one side, noting that other than the HiRes side of it, they are still...

I don't quite understand the need for the 10K ohm resistor that is being put between pins 27 and 28 of larger RAM chips on the zeddy. Do i really need to use it?

Grateful for any enlightenment please.

Thanks very much for this. I eventually socketed the whole board and I was using two Ferranti ULAs. After swapping pretty much everything, I reluctantly pulled a uLA81 from another motherboard (because the new stock still isn't in yet) and tried that... It worked. So I've got two partially failed UL...