Sinclair ZX80 / ZX81 / Z88 Forums

I wonder how long original ULA's would stay in working order if just stored under normal (+/- room temperature, not too dry or moist air, no direct sunlight etc). Let's say, starting with little used or N ew O ld S tock parts. Maybe power up once or twice a year (under carefully controlled condition...

Power supplies using a transformer, rectifiers and smoothing capacitor(s) were very common before the cost of switch mode power supply technology fell in price. DC voltage regulation is very often used inside equipment. Practically required for digital circuitry. Before switch mode psu's became the...

Yes it's common actual supplied voltage is much higher than the nominal of about 9V (both for Spectrum and '80/81). But no-load voltages aren't very useful. Measure under load. High input voltage does not directly influence operation (since internal voltage regulator), but it does affect how much wa...

We all know that fake parts are a common problem on eBay and similar sites. But sometimes you run across an item where the "L@@K FAKE!!" is so thick it's funny. Not to mention lack of knowledge on behalf of the seller: :lol: 14,Z84C0020PEC Z84C0020 NMOS/CMOS Z80 CPU CENTRAL PROCESSING UNIT DIP-40,NR...

Pretty useless in practical sense. But nice reading material anyway. :D now then if any is clever enough to decap a ULA and photograph the final layer, it would be possible to reconstruct the exact logic hiding inside the little vlack chip :mrgreen: Getting at the bare IC die isn't the hard part... ...

Hello all, I've compiled an overview that (apart from speed and package) includes all Z80 CPU's you're likely to come across. Including 100% plug-in compatibles, NOT including almost-compatibles-with-a-few-added-pins, or pin-compatible-with-internal-additions (read: that are not a 100% functional eq...

For a novice it's impossible to remove an IC without a desolder gun. Nope. Practice! Plain iron & solder pump go a long way. I rarely damage IC OR board. But it really takes practice to remove IC's without damaging a board. If that practice is lacking, safest method is to cut pins (and take destroy...

Look closer - @ any point there's like 3 or more gliders visible in that video most of the time.

Very nice video indeed!

Welcome, Gar r y! ;) For fixing your ZX81, what tools you have available? Scope or even a simple logic probe would be very helpful. Any other ZX81's in your possession that you could swap parts with? Usually ZX81's are easy to fix, with 2 exceptions: ULA itself. If that's dead (or its video output b...

Seems to be fixed now, I was able to log in again on WoS. Thank you both Mark & Lee for the help!

Still think it was a problem with WoS site though, as I've not had similar issues elsewhere. Let's hope no other WoS are affected by this (whatever it was).