I recently purchased a Timex/Sinclair 2068 that had an 8-pin DIN socket on the back. I figured it might be a connection for an RGB monitor and, as it turns out, I was right.
This circuit looked nothing like the other RGB designs I’ve seen. Most of those use transistors to generate the sync signals; some use a 7404. This design used a 74HC00, 7408 and LM555.
I think the LM555 was used to generate a signal that would help sync up to the monitor. It may have been a non-standard monitor that needed a different frequency than normal or it may have just been over-engineering.
The circuit is a wonder of point-to-point wiring and was fitted right into the composite out jack on the 2068. Quite ingenious.
Circuit installed in the 2068. 
Component side. 
DIN connector. 
Composite from Q6. 
Orange wire is +5v. 
RGB signals on motherboard.
