How exactly does the Microtan 65 video circuit work?

[BulletMagnet83]

I've been looking for a simple-ish discrete logic video circuit, and this one seems like the closest thing to what I want. The problem is, I can only find the same broad description copy-pasted across several different sites, and my google game isn't strong enough to find an "idiot's guide" to such a thing. I have a schematic, but it's pretty poor and I'm finding it a little difficult to follow.

Does anyone have a very detailed block diagram for this sort of display, or know of any recommended reading that would allow me to teach myself? It would probably be easier to use a 6845 (which looks like it does the same job only better), but bog-standard 74xx parts will probably be available brand-new for the rest of my life, and doing it that way might be more fun

[Alex Eisenhut]

Not sure what you're after, but Don Lancaster's TV Typewriter might be what I think you want?

http://www.swtpc.com/mholley/RadioElectronics/TV_Typewriter.htm