Applications of transputers to astronomical instruments

The application of parallel processing techniques based on transputers to astronomical instruments under development at the Royal Observatory Edinburgh is discussed. On the COSMOS photographic plate measuring machine, a data farm of transputers allows backgrounds to be determined in real time instead of requiring 1.5 h of offline VAX processing per plate. Transputers have been adopted as the embedded processors in a submillimeter bolometer array instrument, and their use is planned in demanding future applications such as thermal infrared array instruments and data compression applied to remote observing. The techniques of interfacing transputers to external hardware and to VAX/VMS computers are discussed. It is concluded that the use of transputers allows one to reconcile the often competing requirements of performance, flexibility, and ease of use. The frequency existence of geometric parallelism allows easy exploitation of the power of parallel processing. Although debugging facilities on transputer systems are less complete than on VAXes, for example, the use of standard high-level languages allows much code development work to be done independently of the hardware