Sinclair ZX80 / ZX81 / Z88 Forums

Quite the lively thread; I love it. I'd be happy to make you up a board That's a very gracious offer sirmorris. In the short term I still think I'd like to wire it up experimentally to prove the concept. If you can afford to wait until my chip arrives and I have time to play, anything I discover cou...

Awesome diagram PokeMon. I don't have any 74HCT02's in my junk collection, so I ordered one. With only 6 connections "external" to the chip socket, I think I'll just wire it up and let the chip float free rather than try to breadboard it. Unfortunately I didn't keep any bad 4116's to do a test with....

That's a very cool explanation PokeMon. I knew one of you tech geniuses would know how to implement it! I think even I understand your discussion well enough to wire it up. I don't know if I will, but it's interesting to think about. Maybe if I get one of my packs figured out to the point where I'm ...

I had some luck a few weeks back with a pack that had a faulty transistor, so I would check that first. Yeah, I finally broke down and bought some exact replacements, ZTX750, on eBay. Replacing the transistors in the 3 still sick packs, one made no difference, another pack heats the 4116's excessiv...

It looks right at home in there Sascha. Don't forget to tell us how it's working out!
Ian

images.jpg Holy thread resurrection Batman! Despite the fact that I've done several 32K mods, and have the chips to do more, I still have a nagging need to know how to fix the 16K RAM packs. No, I haven't diagnosed the power problems on my 3 ailing packs. But I did run into some small success,... C...

As a satisfied customer let me offer my recommendation for this neat little board. It: - is inexpensive - is easy to install with just a tiny bit of soldering - does not require removal of the circuit board from the top shell (i.e. no stress on the keyboard ribbon) - is small and mounts conveniently...

I too was shocked when I touched the ULA after the computer had been running for a time. It gets hotter than hot! Bad ULAs, burned out, are I think the 2nd leading cause of ZX81 demise, after keyboard ribbon breakdown. Unlike keyboard problems however, the only simple source of a ULA replacement is ...

Yes, having read the (thin) manual that came with it I've discovered the "shift" functions, including the editing commands. (I was wondering how to do that,...) I've put tiny stickers on in place of the missing overlay. Sorry Sascha2000; I didn't mean to interrupt and monopolize your thread. It only...

For those of you who've never seen one of these semi-mythical beasts, (which included myself until the postman made me happy yesterday), here is what they look like. The RAM pack is a Timex 1016 and works fine. So would a printer, apparently. The computer has inverse video, and is apparently very cl...