Sinclair ZX80 / ZX81 / Z88 Forums

Thanks.. That’s good to know

A white screen with no cursor usually means ULA is working.. at least the video sync is being created. Before concluding all the ICs are wrong please check them on the working board.. At least the Z80 was not working. But check it on the other board anyway. You may have something wrong with the boar...

XavSnap wrote: ↑Sat Dec 05, 2020 8:02 pm

Code: Select all

1 FOR A=0 TO 15
2 PRINT AT 20,10;"HELLO WORLD"
3 SCROLL
4 SCROLL
5 NEXT A
6 COPY

COPY can't be use on a compressed D_file !
And SCROLL can't be use with a COPY command.

Wow. Never tried it.. what would be the behavior?

tokabln wrote: ↑Tue Jan 19, 2021 10:12 am @1024MAK:

Thanks for your feedback... I do found the problem, which is related to my external Arithmetic Coprocessor Card. Not sure why, without this card, everything works well. So I need to find the (HW/SW?) problem of my card, first.

Again, many thanks

What card is it??

the insulation part is just a plastic strip 20210214_092849-01.jpeg The metal strip is soldered to a point at the edge near the heat sink. 20210214_092644.jpg The other tip should be placed to the other side, like this, to reach the other part of the case. 20210214_092721.jpg Then both halves of the...

Just Like Mark Said..
Beware yours mispositioned.. an lacking an insulator to avoid shorting with the solder points..

Testing Q2 with the multimeter and replacing electrolytics C20, C24, C25, C30, C31 won't harm I guess.
https://www.electronics-notes.com/artic ... r-test.php

Here you can see how I modified video output of mine with the Mark's buffer mod. You can check ULA video output from the pictures. https://www.sinclairzxworld.com/viewtopic.php?f=7&t=3771&p=38736&hilit=1500+composite#p38736 Thanks... That newer board is much more compact for sure... So, if I got th...

Yeah, sorry about being terse. It’s lack of time you see. I was intending on posting some more help today, but have not had much spare time. And then today, the hot water and heating system in the house failed :twisted: , so that took priority... It failed while I was at work. The outside air tempe...

Here is the Schematics.. I don't remember where I did download it from.. credits to whoever