I actually remember the original advert for these things... a guy in a suit driving through the countryside on his way to an important business meeting, but OMG he forgot to finish off an important document. Car pulls into layby and guy gets out, fishes around in the back and pulls out what looks like a fridge with a handle! He plugs it into the cigarette lighter and over the top comes "Amstrad offers you a portable computer solution... the new PPC512 boasts real power on the move!" Yeah, what they didn't show you is it booting up and sucking the life out of the car battery so the business man has to call the AA and have them tow his sorry ass to the convention! He is so late and his crappy computer stats so shit he is fired, becomes a drunken bum and throws himself (chained to his laptop) into the Thames! "Amstrad offers you a portable suicide solution... the PPC512 boasts arm muscle strangling weight for any watery grave"
Nice one, now I look at it, I suppose the bag should have given it away.... The PPC512 was a lot rarer then the PPC640 to the degree that I never saw one ever, it has a crap screen, runs at a speedy 8Mhz, runs off a ton of D batteries if you want to make it portable and has a built in modem... it wasn't that bad, given the price it was one of the cheapest luggables on the market and more importantly it sold well, remember that at one point Amstrad had about 60% or so of the PC (IBM Compatable) market in the UK (add in home computers and it is probably around 70 to 80%).
Amstrad actually did better in computers than most people either care to remember or credit them for. After all, had it not been for Amstrad, you'd have never had the likes of Dell (Hmmm, are we really thanking these guys?) as Amstrad were actually the first company to provide made to order home PC units with the specifications you wanted at affordable prices. Not sure what I mean? Well, after the 8bit market ended and Alan Sugar ignored the development opportunity to produce 16bits games computers in favour of revamping the 6128 & 464 into the + series & that crappy console that was really a 6128, they devised the PC range that later became Viglen computers after Amstrad acquired them and started supply to the public. Amstrad pushed prices downwards and stopped the monopoly created by other manufacturers who refused to supply anything other than the parts they wanted you to have. I've had the pleasure of walking about a mile whilst carrying a PPC. Never again.
The PPC512 is less specced then the PPC640 (which you can find on Ebay) but sold much less, but still don't pay more then £40 for one in its case with the manuals, disks and PSU.