Sinclair ZX80 / ZX81 / Z88 Forums

Transistors connections / pin-outs are normally viewed from below, whereas ICs/chips are normally viewed from above. Also the Ferranti E-line plastic packages have the front with the printing on and the curved corners, unlike the more TO92 cased transistors where the front with the printing is the ...

Mark, thanks for the reply and the link for the french schematics. So it's factory fitted, not a mod. Still, one thing seems odd to me. According to the Ferranti ZTX310 series datasheet I find online, the collector and emitter seem to be switched. If I follow the datasheet, it would seem that the em...

Hi! Bought a couple ZX81, one of them from France. Decided to open this one and it's an Issue 3 with 184E ULA. What's noteworthy is this mod between the board and the modulator input, check the red box on the diagram I made and the pics on Imgur. Just a begginer in electronics but seems that its pur...

Hello to all! Just bought a couple of ZX81, waiting for delivery. Been a ZX Spectrum fan since my teen years (and having a fairly large collection ranging through all models, from my original 48k rubber model to a recently bought +3, and quite a few peripherals), decided to learn how to make the mos...