VIDC1
The VIDC1 was a Video Display Controller chip created as an accompanying chip to the ARM CPU as used in Acorn Archimedes computer systems, its successor the VIDC20 was used in the later RiscPCs.[1]
Video
The VIDC1 can use a color depth of 1, 2, 4 or eight bits per color, from monochrome to 4 to 16 to 256 colors (the VIDC20 can go up to 16 million colors). Also included is a very small color lookup table, just 16 12-bit words, (4096 colors, in 4 bit mode). The 12 bits were split in three 4-bit RGB values, with a 4-bit high speed D-A converter for each of the three primary colors. Its single "sprite" was used for a hardware mouse pointer, which could have three different colors (two bit per pixel, including transparent). The timing generator was fully programmable, and could be clocked with an 8 to 24 MHz clock. Resolutions that could be supported were 1024x1024 in monochrome, 640x512 in 16 colors, or 640x256 in 256 colors.[2]
Sound
The VDC also supported eight-channel stereo logarithmic 8-bit PWM sound.