Sinclair ZX80 / ZX81 / Z88 Forums

Hello and welcome to our forum Staffan!



I hope you enjoy this forum

You are welcome to ask questions!

Mark

The cursor is not likely to be off-screen, more likely is that the video contrast (voltage) is wrong. Hence the K cursor may be there, just not visible. If the picture size was incorrect, I would expect a rolling image, due to incorrect sync. Keep in mind that the transistor type composite modificat...

Ahh, I was going to reply the other day, must have forgotten

As the Opus also uses it's own ROM, has the previous owner fitted or modified the MF1 board with a switch or some other method to disable/prevent it's ROM and RAM from being paged in?

Mark

Hello and welcome to our forum Luke!



I hope you enjoy this forum

You are welcome to ask questions!

Mark

voorsk wrote: ↑Tue Apr 02, 2024 3:34 pm I tried before, and it didn't complain, altho the message is still in my outbox. I can think of a couple more things to post, just in case.

As Moggy says, a PM/DM will sit in your outbox until the recipient reads it. Only then will it move to your sent box.

Mark

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 ...