Computer controlled operation of Ultraviolet Spectrometer and Polarimeter on SMM

One of the computer controlled instruments on the NASA Solar Maximum Mission spacecraft is the Ultraviolet Spectrometer and Polarimeter (UVSP). The computer used has a 31 command instruction set with 4096 words of 16 bit 12 microsecond memory. This has proven capable of driving an instrument with four controllable optical path mechanisms and multiple detectors. The software provided handles time-based and asynchronous interrupts, manages stepper motor timing, controls detector gate timing logic, does simple detector data evaluation, has a variable experiment definition feature, and a command mode function allowing result conditional experiment execution.