>My similar age Acer laptop would make a nice doorstop.
The ZX-81 is pretty hard to beat as a computer-as-doorstop...
(yep, even had the wobbly 16K memory expansion. Never bothered with the hacks to "fix" the problem. I had gotten used to a similar sort of problem with the TRS-80 Model I -- the externally-mounted ribbon cable connecting the keyboard unit to expansion interface would have the annoying tendency to detach)