CSIRAC was the first automatic electronic stored program computer in Australia, and the fourth of its type in the world.

CSIRAC stands for Commonwealth Scientific and Industrial Research Organisation Automatic Computer. The machine was developed by the Council of Scientific and Industrial Research (CSIR, later renamed CSIRO) at its Radiophysics Laboratory in Sydney. CSIRAC ran its first program in November 1949 and commenced regular operation at the Laboratory in 1951. It was transferred to the Department of Physics at The University of Melbourne in 1955, where it was in service from 1956 until 1964.

The development of CSIRAC was led by scientist Trevor Pearcey and engineer Maston Beard. It began as an experiment in high-speed electronic computing for processing increasing amounts of data being generated in scientific fields, including radio astronomy and meteorology.

CSIRAC was one of the first machines in the world to have a ‘stored program’, which allowed computer programs and data to be accessed instantaneously. Previous machines had to be programmed before each new operation.

Working with CSIRAC

CSIRAC is large and complex: its components cover 40 square metres and weigh approximately two tonnes. It required a specialised team, which included Melbourne engineers Ron Bowles and Jurij Semkiw, for maintenance and programming operations.

Ron and Jurij normally began their working day with CSIRAC with a one hour ‘warming-up’ period. During this time, they gradually activated over 2000 valves used to process data. A stable power supply was essential for the efficient operation of the machine. On one occasion, an unexpected fluctuation in power supply occurred when someone plugged in an electric jug in a nearby tearoom and overloaded the entire computer!

Photo of Ron Bowles making adjustments to CSIRAC

Maintenance engineer Ron Bowles makes adjustments to CSIRAC
Source: The University of Melbourne / © Herald and Weekly Times

Programs and data were fed into CSIRAC via paper tape. CSIRAC’s main memory for storing the programs and data consisted of electronic circuitry and a series of metal tubes containing mercury, called ‘acoustic delay lines’. The memory was temperature-controlled and, like the power supply, had to be kept constant. On hot days in summer the computer was often switched off to prevent it from overheating.

Each new project that CSIRAC computed required a custom written program. Early programmers had to be experts in CSIRAC ‘machine code’. After 1960, a more user-friendly language, INTERPROGRAM, allowed programmers to write instructions in English.

CSIRAC was able to operate up to 1000 times faster than the best mechanical calculators of the day. But calculations on the computer could still take hours and even days to complete. People sometimes worked through the night waiting for results.

CSIRAC and a modern laptop (2004)

The table below compares CSIRAC to a modern laptop:


CSIRAC, 1949

Laptop, 2004

Processing speed

500–1000 Hz

2000 million Hz

Memory capacity

2000 bytes

600 million bytes


40 sq m

0.2 sq m


2500 kg

2.5 kg

Power consumption

30 000 watts

10 watts


2000 valves

Microchip equivalent to tens of millions of valves

CSIRAC at work

During its regular operation in Sydney, CSIRAC functioned as a computing service for scientists and engineers. Users normally sent in their programs for CSIRAC staff to execute.  Programs undertaken on the computer in Sydney included water behaviour simulations for the Snowy Mountains Hydroelectric Authority and studies in road and air traffic congestion.

Photo of Ron Bowles at the CSIRAC console

Ron Bowles at the CSIRAC console, University of Melbourne, 1956
Source: The University of Melbourne

CSIRAC was transferred to The University of Melbourne in 1955 under the care of Dr Frank Hirst. Its arrival enabled the University to establish one of the earliest Computer Science departments in the world.

CSIRAC users in Melbourne took a hands-on approach, writing programs and physically operating the computer. Programs run on CSIRAC included the first electronically computed 24 hour weather forecast in Australia, and the calculation of housing loan repayments for university staff.

In Melbourne CSIRAC inspired a new degree of public awareness about the potential of computers. Demonstrations at university open days were a favourite with visitors, who could see CSIRAC calculate such things as reflex reaction times and predictions for the patterns of bouncing balls.

After CSIRAC was decommissioned in 1964, Computer Laboratory manager Dr Frank Hirst arranged the donation of CSIRAC to Museum Victoria. The computer now forms part of the Museum’s Technology Collection. In 2004 CSIRAC was put on display in the Science and Life Gallery at Melbourne Museum.

Further Reading

Beard, M and Pearcey, T. 1984. The Genesis of an Early Stored-Program Computer: CSIRAC. Annals of the History of Computing 6(2) 106.

McCann, D. and Thorne, P.  2000. The Last of the First: CSIRAC: Australia’s First Computer. Department of Computer Software Engineering, The University of Melbourne.

Comments (8)

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Ron Collis 19 August, 2011 21:10
I was involved in your early days with the Victorian Government Actuary and requests for loan repayment schedules for Government Authorities.
dorothy byers 10 April, 2012 20:49
I just love your CSIRAC pages of very computers do you have some info on them?dorothy
Discovery Centre 11 April, 2012 12:15
Hi Dorothy, there are some more resources listed at the bottom of the page, and further resources listed down the right hand side, hope this helps!
Sheridan Williams 21 October, 2012 04:45
I work at the National Museum of Computing (home of Colossus and the WITCH) at Bletchley Park and will be in Melbourne from 1-3 Nov. I'd love to come and see CSIRAC and take some photographs, would this be possible?
Discovery Centre 21 October, 2012 10:51

Hi Sheridan

CSIRAC is currently on display at the Melbourne Museum on the lower ground floor. This is a free area of the museum and you are more than welcome to take photographs of CSIRAC.

Helen McHugh 21 May, 2013 10:06
I am Brain McHugh's daughter. I went looking on goggle to see mentions of him with CSIRAC and could find nothing. He and Geoff Hill were the first 2 programmers on CSIRAC. He is mentioned in the book Last of the First
Discovery Centre 25 May, 2013 15:32

Hi Helen,

The following Museum Victoria webpages have information and images relating to your father; Photograph - Brian McHugh, 1990s, CSIRO Division of Radiophysics, 1952.

Mrs Judy Astall 7 May, 2014 16:47
Frank Hirst was my father's cousin and I remember as a child going to an open day at Melbourne Uni. to see CSIRAC. Absolutely fascinating and I have never forgotten it. Imagine to my surprise going to Melb. Museum one time and seeing film and press clippings of CSIRAC and Uncle Frank. It is just amazing at how technology has advanced since 1956 and I really can't help but be proud that a member of my family has helped it along the way.
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