STICdigitizer (for Intellivision) - c0pperdragon/LumaCode GitHub Wiki
This board can be installed into a vintage Intellivision game console to create a lumacode representation of the display. This lumacode signal can be processed with a compatible upscaler to deliver a pixel-perfext HDMI display.
Theory of operation
The circuitry is quite simple as all video information is available in digital form, so all that is needed is to serialize the 5-bit color+sync information to lumacode which can be done with a flip-flop, a multiplexer and some logic gates.
Installation details
Solder the mod board to the underside of the mainboard, just under the STIC chip. Use the "1" marking to get the orientation correct. Bring out the lumacode signal with some wire and maybe install a permanent RCA socket to the case.
To avoid using the RF signal altogether, consider installing an A/V mod. Please refer to other sources on how to do this, as this goes beyond the scope of this documentation.
There is a great video from Mark showing how to do this installation.
Details on color encoding
The Intellivision uses a 16-color palette so every pixel needs 4 bits to encode its color. This is done by two lumacode samples, the first encodes the two most significant bits, the second sample the two least significant bits. Assignment of colors to these indizes can be found in this wikipedia arcticle