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Pixar Image Computer

P-II Pixar Image Computer

The Pixar Image Computer (also known as the PIC for short) was a graphic designing computer originally developed by the Graphics Group (which would later become Pixar). It was designed for the high-end visualization markets.

History

In 1984, the Graphics Group, Lucasfilm's computer division, showed off the prototype of the Pixar Image Computer at the SIGGRAPH computer graphics conference, in addition to a partially-completed version of The Adventures of André & Wally B. having premiered there.

Released commercially for the first time on February 3rd, 1986, some time after Steve Jobs bought out the Graphics Group and renaming it Pixar, the Pixar Image Computer was intended for commercial and scientific high-end visualization markets, such as media production and medicine. It had a price tag of $135,000, but it had also required a $35,000 workstation from Sun Microsystems or Silicon Graphics to operate it. It proved to be ahead of its time, and had generated a lot of single sales. However, it did not sell in quantity.

In 1987, Pixar developed the second-generation Pixar II (P-II for short) image computer, a low-cost model which sold for $30,000.

In an attempt to gain a foothold in the medical market, Pixar donated ten machines to leading hospitals and sent marketing people to doctors' conventions. However, this had little effect on sales, despite the machine's ability to perform CAT scans and show perfect images of the human body. Pixar did get a contract with a manufacturer of CAT Scanners, which sold 30 machines. The terms were: Buy a million-dollar scanner, and get a $30,000 3D visualization system free. However doctors were not trained to look at 3D, and could be sued unless they looked at the individual slices, as per their training. By 1988, Pixar had only sold 120 Pixar Image Computers.

In 1988, Pixar began development of the PII-9, a nine-slot version of the P-II. This machine was coupled with the world's first RAID (Redundant Array of Independent Disks) assembly, a high performance bus, a hardware image decompression card, four Channel Processors (CHAPs), very large memory cards (VME sized card full of memory), high resolution video cards with 10-bit DACs which were programmable for a variety of frame rates and resolutions, an overlay board which ran the NeWS windowing system, and finally, the 9-slot chassis. A full-up system was quite expensive, as the 3 GiB RAID was $300,000 alone. At this time in history, most file systems could only address 2 GiB of disk.

This system was aimed at high-end government imaging applications which were done by dedicated systems produced by the aerospace industry, which cost a million dollars per seat. The PII-9 and its associated software became the prototype of the next generation of commercial "low cost" workstations.

By 1990, the Pixar was defining the state-of-the-art in commercial image processing. However, the government decided that the per-seat cost was still too high for mass deployment, and to wait for the next generation systems to achieve cost reductions. This decision was the catalyst for Pixar to lay off its hardware engineers and sell the imaging business. There were no high volume buyers in any industry. Less than 300 Pixar Image Computers were ever sold.

The imaging business was sold to Vicom in 1990 for $2,000,000. Vicom filed for Chapter 11 within a year. Many of the lessons learned from the Pixar Image Computer had transitioned into the Low Cost Workstation (LCWS) and Commercial Analyst Workstation (CAWS) program guidelines in the early and mid 1990s. The government mass deployment that drove the PII-9 development occurred in the late 1990s, in the Integrated Exploitation Capability (IEC) program.

Technical Details

Channel Processor (CHAP)

The Channel Processor (CHAP for short) is a four-way parallel (RGBA) image computer made up of four 16-bit AMD 21116 bit-slice processors (each running at 10 MHz) and four Logic Devices LMU17 16 x 16 hardware multipliers in an SIMD (Single Instruction Multiple Data) architecture, which was ideal for imagery and video applications. It can execute instructions at 40 MIPS, making it 200 times faster than a DEC VAX-11/780, which was a popular system at the time. The CHAP processed four image channels in parallel; One for red, one for blue, one for green, and one for transparency (alpha channel). The CHAPs can communicate with each other and other peripherals over a 80 MB/sec YAPBUS (Yet Another Pixar Bus), and to picture memory (VRAM) across the 240 MB/sec PBUS (Processor Access Bus).

Specs

  • No. of parallel processors per CHAP: 4
  • No. of CHAPs per system: 1 to 3
  • Data word width per processor: 16 bits
  • Clock cycle time: <100 ns
  • Control store memory: 16K words (96-bit words)
  • Scratchpad memory: 16K x 16-bit words x 4 (64K words total)
  • Memory bus bandwidth: 240 MB/sec
  • YAPBUS bandwidth: 80 MB/sec

Memory

The PIC and variations thereof can accommodate 12 to 192 MB of image memory (VRAM), storing full-color pixels at 48 bits for each pixel. The pixels use 12 bits for red, green, and blue, plus 12 bits for the alpha channel. Memory bandwidth is at 480 MB/sec.

Interfacing to Host Machines

The PIC did not have a direct user interface, meaning that it cannot be used on its own. For this, it requires a Unix-based workstation acting as a host machine to operate it (at least to provide a keyboard and mouse), from brands such as Sun Microsystems or Silicon Graphics. The system interfaces to the host machine via the SYSBUS. It is used as a special-purpose graphics system for a variety of host machines, from personal computers to supercomputers. The host machine can be positioned up to 30 feet from the PIC.

Video Output

The standard video output board of the PIC has a high standard screen resolution of 1024 x 768 pixels interlaced, and a high broadcast quality standard RGB output of 525 lines (625 lines for PAL regions). It has 3 color lookup tables (10 bits in, 10 bits out), 10 bits per DAC, and a video bandwidth of 480 MB/sec.

Chassis

The original PIC boasts a rack-mounted box chassis measuring 21" x 19" x 30" with 12 slots for expansion boards, and weighs 100 to 150 lbs (45 to 68 kg).

The minimum configuration holds six boards, comprised of one CHAP, one video board, one memory controller, and three 8 MB memory boards. This can be expanded to three CHAPs, two video boards, and six memory boards.

The P-II (Model 820204) uses a chassis that could accommodate four expansion boards, eight less than the original, considering that it is meant to be a lower cost model. A variant of the P-II features five expansion board slots. It is distinguished by a redesigned case and front faceplate. It is slightly smaller than the original PIC at 21" x 17.5" x 23.5", and weighs 140 lbs (63.5 kg).

The PII-9 uses a similar rack-mounted form factor to the original PIC, with the exception that it could accommodate nine expansion boards, rather than twelve.

Power

The PIC runs on 190 to 250 volts of AC power @ 20 amps, single phase, at 47 to 63Hz

Software

The Pixar Image Computer comes with an extensive software package, which was developed in-house by Pixar under Unix 4.2 in both the C and Assembly programming languages, for developing applications.

Trivia

  • Walt Disney Feature Animation, whose parent company later purchased Pixar in 2006, used dozens of the Pixar Image Computers for their CAPS system and was using them in production up through Pocahontas in 1995.
  • The Pixar Image Computer was only used on one Pixar film - the dream sequence of Red's Dream. This is because that the Reyes rendering environment was too complex for the system, so it had to be trimmed down to basic functions so it could work.

Gallery

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