This began when the video on the Robotron machine stopped working. I hooked up an external multisync monitor to the video outs on the motherboard. I was surprised at how simple and primitive the analog video signals are: vertical sync, horizontal sync, red, green and blue levels, and ground. I want to put a scope on the sync lines and look at their timing. I want to intercept the r,g, b lines and force a different video signal onto the monitor -- even if it's just to make the whole screen light up red or green or blue. I want to look at the Robotron schematics and see how bytes in screen memory become levels of rgb at the right times. I want to build my own video generator. I want to look at projects from the 70s and 80s that deal with analog video. I want to look at the history of video.
A large part of what makes this possible is the discovery in the Physics storeroom of the NEC multisync monitor from 1987. It seems incredibly versatile. I found manual pages for it online, which I'll link to here as soon as I refind them. In its analog mode it has the required h and v sync lines, and rgb and ground lines. And it just worked when I wired it up to the Robotron. I need to find a proper DB9 connector for it.
Stuff to do:
- Identify video signals from the motherboard
- Continuity test the video harness
- Prototype NEC connection, play
- Find a DB9, make a harness
- Soldering skills
- Video basics
- Explore schematics, how do bytes in RAM become levels of rgb at the right times?