Sinclair ZX80 questions

Tony Duell wrote: Out of interest, what was so bad about them that wasn't typical of that class of machine around that time? Admittedly without having been involved at the time, it seems with hindsight that there were an awful lot of similar machines around that sort of era with odd design quirks, very limited power, poor-quality PCBs etc. The construction guide says: "both regulators and a heatsink should be fitted to all Atoms". I've never seen one with only a single regulator, but doubtless a few individuals building from kits tried it. The manual gives the minimal system with 2KB of memory as around 750mA draw, so that's within the capabilities of some 7805 variants and not others... More common is that the regulators have been bypassed or removed entirely and an external supply is used. It's rare-ish to find an Atom with regulators and heatsink still intact (maybe 25% are like this). Rarer still is to find an Atom using an external supply where someone's actually done as the manual says and indicated on the back that the machine's wired for 5V regulated input rather than 8V unregulated - I expect there are a lot of toasted Atoms still floating around! cheers J.