The CIRRUS Computer - Computing & Computing Science Collection

CIRRUS in operation, with R.J. Potter in the foreground, and W. Dorfl in the back room.

The CIRRUS computer was a “second generation” Australian designed and built machine, with a transistorised, magnetic core memory and a microcoded controller. It was provided with a symbolic Assembler code and a modern Compiler language. One of the original design team members, Gordon Rose, recalled the name was formed by combining letters from CSIRO, WRE and UA with the S from satellite. The name had an additional metaphorical meaning from the cirrus cloud, where the exploratory nature and initial theories were in a sense as far-reaching and sweeping as the cloud formations. Built at the University of Adelaide by the Electrical Engineering Department between 1959 and 1962, CIRRUS was intended to be suitable for scientific calculations, as well as attain maximum computing power within a ‘modest’ budget. Prior to this the University had access to the IBM 7090 held at the Weapons Research Establishment (WRE) in Salisbury, or used teams of human ‘calculators’.

The microcoded instruction sets stored in changeable read-only memory, together with multi-tasking, timesharing, interactive multi-user ability and a complex memory management, ensured CIRRUS was the first computer of its generation to have these features, a prelude to the computer designs for the next decade. It was also a significant investment by the University in the study of computers and computing science. The University underwrote the project initially to the amount of £15,000 to initiate computer research activities at the University. This received generous industry support as well. CIRRUS remained in use by the University until 1971, when its hardware maintenance issues proved to be unsustainable for operation.

CIRRUS is now a part of the University of Adelaide’s Computing & Computing Science Collection. Professor Emeritus Chris J. Barter’s article “The CIRRUS Computer: Its Design, History and Significance” explains in more detail CIRRUS’ contribution to computing history. Please click here to read more. The earliest comprehensive description of the CIRRUS design is “The Design of a Digital Computer”, Report No. 1 of the Digital Techniques Laboratory, produced by the Electrical Engineering Department of the University of Adelaide in November 1959. A brief guide to the Report can be found here, and a PDF copy of the report is available here. For more information on the people behind the CIRRUS project, please click here.

Inside view of CIRRUS mainframe