Once upon a time....
There were a bunch of these in the early hobby channel,
say, around 1981... the seller had complete instructions
for interfacing them, and included some rudimentary code
for using overstrikes to simulate characters bot available
in its 5-level (Murray?) coding scheme.
They were going for $150 at the time, and I still could
kick myself for not grabbing one, they looked pretty cool.
Anyone got a garage full of them?
-dq