If you are really game for a challenge we could recreate the Display Circuit from the SCRUMPI 3 - two challenges met with one task...
Just saying like. I paid for access to the Journal article where he describes how it works but, they did not supply the circuit diagram he mentions - I need to chase that up.
For those who remember the Pong video I had a reply from him and he confirmed he was using a RAM expansion - this thread has some nice pictures of the backplane he made to have an external RAM board and the VDU...
https://translate.google.co.uk/trans...78640%23p78640
Scroll up a bit to see the other photo as the link is direct to one of them half way through the thread.