As part of my obsession with old home computers, I recently spent some time looking around ZX80 and ZX81 sites on the Net. If anyone's interested in building a ZX80 from scratch and you have some electronics experience, may I recommend Grant Searle's site. One point regarding this site: Mr. Searle moved it from Freeserve to BT Openworld, but forgot to change a couple of links on the new page: ZX80 A4 schematic & ZX80 A3 schematic.
I have a ZX80 of my own around here somewhere - it's upstairs in the junk room, needing to be repaired: it has a problem with its voltage regulator and some damage to the double-sided PCB which will require care to fix. The main problem is that I've lost it: it's in a carrier bag somewhere in the mess that is the storeroom.
(04-Oct-03: It's not in the storeroom - I've lost it! I turned the house upside-down looking for it and have had no luck. If anyone has a spare ZX80 that they'd like to sell, any chance of lobbing it this way? You'd be rewarded handsomely, of course. :)