I now own a computer I've been wanting since the '80s for no reason other than it's as utterly cheap in price and quality as a fully functional home computer could get: A Timex Sinclair 1000. The picture quality is delightfully crappy. Unfortunately, half the keyboard doesn't work, which probably means its super-cheap ribbon cable kinked & broke.
Oh, wow, fantastic ideas if I can't repair the membrane keyboard, made all the better by the fact that I work next to an indy Radio Shack dealer.
A DIY ZX81 Keyboard Period Document: http://www.zx81keyboardadventure.com/2018/06/a-diy-zx81-keyboard-period-document.html
Timex Sinclair 1000 (USA's ZX-81) repair (+)
The replacement ZX81 keyboard arrived, and the ribbons look and feel much more substantial. The only cosmetic differences are a slightly different font, shift-0 is rubout instead of delete, and enter is "new line" instead. Time to clean off the gunk from the top of the case so I can put the new keyboard in.
Timex Sinclair 1000 (USA's ZX-81) repair [++]
It works! I should probably remove the RF modulator cover & see if that can be cleaned up, but it works.
The test keypresses were: P {Shift-P} 1 2 3 4 5 6 7 8 9 0 Q W E R T Y U I O P A S D F G H J K L {Space} {period} M N B V C X Z {Enter (now New Line)}
I also had a kaleidoscope program in a .wav file ready for testing. Android won't let you keep the headphone jack volume at "Marty McFly," but the Sinclair can't hear anything softer.
Tilted Goldeneye carts aside, computers generally don't like it when parts of the memory map suddenly go missing.
I left the ZX81 alone in the kaleidoscope program, and after the same long delay, it started the weird colors again. I turned the TV off and back on, and not only were the colors still there, the TV took most of a minute rolling, fading to & from static, alternately showing something & "no signal," to sync with the ZX81's signal again.
Now I've got to either dive into uncharted territory (the RF modulator) or look at a composite mod. Help & pointers appreciated.
Well, that's a new one... I left it alone for a while, then when I went back, it was doing this weird coloring thing. I started a game then took a photo: