CSIRAC main-frame thermonic valve (vacuum tube) technology stored-memory digital electronic computer. 768 words storage in mercury delay lines, 20 bit words. Comprises multiple metal cabinets containing power unit, CPU and processing circuitary, printers, storage delay lines, hard disk drive storage unit, paper tape readers and punches.

Originally known as CSIR Mark 1, CSIRAC computer was designed in 1947 by Trevor Pearcey and Maston Beard at the Division of Radiophysics, of the Council for Scientific & Industrial Research (CSIR - today known as CSIRO). Construction was commenced in Sydney in 1948, and the first program was run in 1949. The machine was in full operation by 1951. It embodied many features novel at the time and was able to operate more than 1000 times faster than the best mechanical calculators. CSIRAC is generally acknowledged as the first stored-memory electronic computer in Australia and it today the world's only complete surviving first-generation digital electronic stored-memory computer.

In 1955 the computer was transferred to the University of Melbourne, Computation Laboratory, where it was renamed CSIRAC, and continued to operate until November 1964.

The date range (1949-1964) is given to indicate that changes were made to the structure and circuitry over the period of CSIRAC's working life. CSIRAC is listed on the Victorian Heritage Register, Number H2217 and has been awarded a National Engineering Heritage Landmark plaque by Engineers Australia.

Physical Description

CSIRAC at Melbourne consisted of two rows of cabinets, a control console, input and output devices, test equipment and an off-line paper tape editing area. There were nine cabinets, five in the front row and four in the back. Cool air was blown up through all the cabinets from the basement below. The auxiliary memory (disk drive) occupied the middle space that would have been occupied by a cabinet in the back row. The five front row cabinets contained (from left to right viewed from the front) power supplies, input and output circuitry, clock and control circuits, arithmetical circuits and memory control circuits. The four back row cabinets contained (from left to right viewed from the front) power supplies, auxiliary store control circuits, 'disk drive', auxiliary test power supplies and memory control circuits.


CSIRAC was the fourth stored program computer in the world and the first one in Australia. It is the only intact first generation computer left on the planet.

More Information