Current status of the HDS200 terminal:

[Linked Image from i.imgur.com]

It's missing some kind of synchronization between the Z80DMA and the SCN2674, so the video looks a bit weird. Hard to figure out what exaclty it needs without schematics or being able to trace some lines.

Bonus screenshot:

[Linked Image from i.imgur.com]

RS232 works, most keyboard keys work, so it's kind of usable.