NYT -- IBM began development work on Columbia's flight computers in 1972, nine years before the first spacecraft was launched. The company chose the best and most appropriate pieces of technology from its various products and its research laboratories, and came up with a hybrid machine, the IBM AP-101.
Over the years, shuttle scientists have installed improvements to the AP-101, like solid-state electronics for its memory instead of magnetic disks. Yet the basic design of the five onboard AP-101 computers — black cubes about 18 inches on a side — remains the same.
The programming language used for these unusual machines is similarly tailored for its task. It is called HAL/S (high-order assembly language/shuttle), and was specially developed for space-flight applications like instantaneous handling of streams of data from shuttle sensors.
The AP-101 computers process data at a tiny fraction of the rate of today's personal computers. Yet today's computers need a lot of processing firepower because they routinely handle big graphics, as well as audio and video files. All of that is important for people playing computer games or downloading music over the Internet but not relevant to the shuttle's performance.
Steve Lohr]
6:45:21 AM 
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