Sinclair ZX80 / ZX81 / Z88 Forums

Hi, I am getting back into ZX81 (well really TS1000 for me) development. I wrote BASIC programs as a kid, then went on to a career in all sorts of programming, but now I am removed from that life and want a piece of it back. I don't have the time and attention span at the moment to learn Z80 assembl...

Temporarily jumper the two pins on the motherboard keyboard connectors that make "V" and if it registers with the computer, then it's definitely a membrane problem.

I would also like to see how double buffering is done on ZX81. I am just playing around with z88dk right now and not getting too far with that.

Wondering if there will be another run? *Just* missed out on this one.

And here's the new TS 1000, which I just fitted with PokeMon's keyboard upgrade and composite video, and equipped with the ZXpand+ for new adventures. Yeah, I need a new place to put it.

Conclusion: I still think it's the ULA but I'm not sure. I bought a second "like new in box" TS 1000 and I'll use that going forward for my TS 1000/ZX81 adventures. I don't want to risk damaging its good ULA by swapping it into this TS 1000. Also, by reading old threads on this forum, I found a diff...

I used the ZX81 Tape Converter you referenced extensively to revive my 30+ year old programs stored on dodgy bargain cassettes. It has a realtime program listing so as you correct dropouts and errors, you can see results immediately. I revived my dumb old BASIC creations and thanks to ZXpand, I can ...

The modulator can be the cause of some video picture distortion. I can't really tell from the photo you posted. Mark The degradation appears as solid black and white lines running across each character cell, one scan line high, randomly appearing. Seems like a problem in image generation, thus my f...

I would guess this is heat related as a turn off and cool down temporarily cures it. My views on heat sinking a chip in an enclosed environment with no air movement through the case are well known here and suffice to say I find it a redundant exercise. My intention is to put the case back together ...

Ok, one last picture and I'll quit littering this board with pictures of my mess. I received my ZXpand+ today and it's pretty cool. Having something cool on my TS1000 meant I had it turned on longer than when I've just been troubleshooting it. The result is that the screen starts to become corrupted...