He later had books mentioned in other comments: "The Cheap Video Cookbook" and "Son of Cheap Video". In these he added just a few TTLs to a Kim-1 computer and generated video using mostly software.
The Sinclair ZX-80 was much closer to this than to the TV Typewriter (which was 100% hardware). Some other computers that used this technique back in the day:
The Sinclair ZX-80 was much closer to this than to the TV Typewriter (which was 100% hardware). Some other computers that used this technique back in the day:
https://en.wikipedia.org/wiki/Aamber_Pegasus
https://en.wikipedia.org/wiki/Galaksija_(computer)
And here is a recent project:
https://en.wikipedia.org/wiki/Gigatron_TTL