The Vidiot (formally known as “Video Hybrid”) is a small custom board that takes the digital RGB signal from Denise (4 bits per Red, Green and Blue component) and translates it to a 16-level analogue signal per component suitable for display on analog TVs and or monitors.
It is found on the Amiga 2000 (but not on the early “german” Amiga 2000-A), Amiga 500, Amiga 3000, CDTV and the Amiga 500 Plus and is universal (PAL / NTSC agnostic).
The Amiga 1000 and the early “german” Amiga 2000-A (which is based on the Amiga 1000 anyway) implement an onboard equivalent to the Vidiot.
The Amiga 3000 and Amiga 3000T use two Vidiots, the second one for the onboard flicker fixers VGA port.
The Vidiot consists of three resistor networks (one for each 4-bit colour component).
Roughly, each of the 4 bits activates or not a resistor. With proper wiring and resistor values, the 16 possible 4-bit combinations produce 16 resistance levels which result in the 16 necessary voltage levels for each component’s analog signal.
An additional function of the Vidiot is the production of a monochrome composite video signal, on the Amiga 2000, Amiga 500 and Amiga 500 Plus.
On the Amiga 3000, CDTV and Amiga 3000T this function of Vidiot is unused. The colour composite signal commonly available on the CDTV comes from a separate board connected to the video slot.