Search found 349 matches

by RetroTechie
Wed Aug 15, 2018 7:27 am
Forum: SALES
Topic: ZX81 ULA
Replies: 65
Views: 9174

Re: ZX81 ULA

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...
by RetroTechie
Wed Aug 15, 2018 6:53 am
Forum: Hardware
Topic: PSU Voltages.
Replies: 5
Views: 808

Re: PSU Voltages.

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...
by RetroTechie
Sat Aug 11, 2018 3:01 am
Forum: Hardware
Topic: PSU Voltages.
Replies: 5
Views: 808

Re: PSU Voltages.

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...
by RetroTechie
Thu Jul 26, 2018 2:49 am
Forum: SALES
Topic: Fakeness overload
Replies: 0
Views: 1431

Fakeness overload

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...
by RetroTechie
Fri Jul 20, 2018 10:33 pm
Forum: Sinclair Misc
Topic: Ferranti ULA doc may be of interest
Replies: 12
Views: 2287

Re: Ferranti ULA doc may be of interest

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... ...
by RetroTechie
Thu Jul 05, 2018 10:21 pm
Forum: Sinclair Misc
Topic: Z80 CPU part number cross reference
Replies: 1
Views: 312

Z80 CPU part number cross reference

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...
by RetroTechie
Thu Jul 05, 2018 9:22 pm
Forum: SALES
Topic: ZX81 ULA
Replies: 65
Views: 9174

Re: ZX81 ULA

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...
by RetroTechie
Wed Jun 27, 2018 7:18 pm
Forum: Software
Topic: ZX81 Youtube videos
Replies: 2
Views: 1060

Re: ZX81 Youtube videos

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

Very nice video indeed!
by RetroTechie
Wed Jun 27, 2018 7:08 pm
Forum: Welcome Area
Topic: Hello
Replies: 4
Views: 541

Re: Hello

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...
by RetroTechie
Wed Jun 13, 2018 9:38 pm
Forum: ZX Spectrum Lounge
Topic: Any WoS admins on here?
Replies: 5
Views: 2554

Re: Any WoS admins on here?

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

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).