I'm doing some research on Bob Leland W8GBT who in the 70s formed a company with a couple of ham buddies to produce a video display RTTY converter called the Viditype model 872:

It was a competitor to the HAL RVD-1002 and was produced in the 1973-76 timeframe.  I'd be very interested in hearing from anyone  who remembers them, or might have used one or has one.

Thanks and 73,

Bob W9RAN