Editing Pixar Image Computer (section)

== Design ==
The P-II could have two Channel Processors, or Chaps. The chassis could hold 4 cards. The PII-9 could hold 9 cards (4 Chaps, 2 video processors, 2 Off Screen Memory (OSM) cards, and an Overlay Board for the [[NeWS]] windowing system). NeWS was extended to control the image pipeline for roaming, image comparison, and stereo image viewing.

Each Chap is a 4-way parallel ([[RGBA color space|RGBA]]) image computer.<ref name="Levinthal" /> This was a [[SIMD]] architecture, which was good for imagery and video applications. It processed four image channels in parallel, one for red, one for green, one for blue, and one for the [[alpha channel]] (whose inventors have connections to Pixar).<ref name="AutoFZ-2" /><ref name="Porter" /> The Chaps did 16-bit integer arithmetic.

The memory for images only stored 12 bits per color channel (or 48 bits per pixel).<ref name=":0" /> 4 bits of extra precision were added to the end when loaded into the Chaps.

A [[Unix]] host machine was generally needed to operate it (to provide a keyboard and mouse for user input). The system could communicate image data externally over an 80M<!-- Is this megabytes or megabits? --> per second "Yapbus" or a 2M per second multibus to other hosts, data sources, or disks, and had a performance measured equivalent to 200 [[VAX Unit of Performance|VUPS]], or 200 times the speed of a [[VAX-11/780]].<ref name="AutoFZ-6" />{{For what?|date=March 2021|reason=Does this refer to the P-II or the PII-9?}}