Sinclair ZX80 / ZX81 / Z88 Forums

You can't force a NMI. A NMI is a non-maskable interrupt which is a hardware signal. Machine code can jump to the address where the NMI routine is, but it's not quite the same. Machine code can HALT the processor, just execute the HALT instruction. But this will not do what you want on a ZX81. I pre...

can a " twisted " cable solve this ? Not with a twisted cable designed for PCs, as it will also twist the motor on line, but the Opus only has a single (common to all drives) motor on signal, as it uses a Shugart interface. Shugart interface Floppy Drive Interface Pin Function 2 /DCD Disk Change De...

sP1d3r wrote: ↑Sun Mar 31, 2024 8:51 am Many thanks, my Android 13 phone only said that the site took too long to respond.

Its someone's personal server at home I believe, at least, it was when I first discovered this very useful site.

Mark

sP1d3r wrote: ↑Sat Mar 30, 2024 10:47 am

Lardo Boffin wrote: ↑Fri Mar 29, 2024 12:14 pm I believe you can configure these to be used as master / slave RAM packs:

https://k1.spdns.de/Vintage/Sinclair/80 ... Manual.txt

The link is broken, BTW.

The link that Lardo posted?

It works for me.

Anyway, I've attached a copy.

Mark

With your Kempston joystick interface fitted, test the signals I mentioned in my earlier post to see if any are flatlining or otherwise wrong. So, test these pins on the Z80: Pin Signal 6 Clock 7 D4 8 D3 9 D5 10 D6 12 D2 13 D7 14 D0 15 D1 17 /NMI (should be always high) 18 /HALT (should normally be ...

Not sure it's the ULA. Depending on which version (there were a surprising number not including the various clones), a basic Kempston joystick interface only typically uses the eight data bus lines (D0 to D7), address line A5 (and sometimes A6 and A7), /RD, /IORQ and sometimes /M1. And obviously, +5...

Yes, I think you can use those.

Mark

Hello and welcome to our forum Graham! :D :D :D I hope you enjoy this forum :D You are welcome to ask questions! I've not heard of the ULAdigitizer before. It looks like it either copies the video data from the ULA data bus when the ULA reads the video data from the 'lower' RAM, or when the Z80 wri...

No, you can use any computer language that was/is available for the Sinclair machine you are using.

Mark

No

Mark