CSIRAC

CSIRAC, Australia's first digital computer, as displayed at the Melbourne Museum

CSIRAC ( /ˈsaɪræk/; Council for Scientific and Industrial Research Automatic Computer), originally known as CSIR Mk 1, was Australia's first digital computer, and the fourth stored program computer in the world. It was first to play digital music^[1][2] and is one of only a few surviving first-generation computers (others include the Zuse Z4 and at least two Ferranti Pegasus computers).

The CSIRAC was constructed by a team led by Trevor Pearcey and Maston Beard, working in large part independently of similar efforts across Europe and the United States, and ran its first test program sometime in November 1949.

The machine was fairly representative of first-generation valve-driven computer designs. It used mercury acoustic delay lines as its primary data storage, with a typical capacity of 768 20-bit words (later doubled), supplemented by a parallel disk-type device with a total 1024-word capacity and an access time of 10 milliseconds. Its memory clock ran at 1000 Hz, and the control unit, synchronized to the clock, took two cycles to execute an instruction (later the speed was doubled to one cycle per instruction). The bus (termed the "digit trunk" in their design) is unusual compared to most computers in that it was serial—it transferred one bit at a time. The instruction set was minimal, but supported the basic set of arithmetic and logical operations, as well as conditional and relative jumps (making it possible to write a library of subroutines).

Input to the machine was performed in the form of punched paper tape, after experiments with punch cards proved unsatisfactory. The machine was controlled through a console which allowed programs to be stepped through one at a time, and featured CRT displays which showed the contents of registers. Output was through a standard teleprinter or to punch tape.

The machine, like all machines of the era, had no operating system. A high-level interpreted programming language called INTERPROGRAM was developed in 1960 by Geoff Hill. It was similar to early forms of BASIC, which was designed in 1963 for the 20-bit transistorized GE-200 series.

In 1950 or 1951, CSIRAC was used to play music, the first known use of a digital computer for the purpose. The music was never recorded, but it has been accurately reconstructed^[2].

CSIRAC, side view

In 1955, with the CSIRO's decision that computing research was outside its purview, the machine was transferred from its home at the Radiophysics Laboratory at the CSIRO in Sydney, to the University of Melbourne, where it formed Australia's only academic computing facility until late 1956. Many pioneers of computer use in Australia had their first exposure to computing there.

Most of CSIRAC's approximately 2000 valves were of the types 6SN7,^[3] 6V6,^[4] EA50 Diodes and KT66.^[5] George Semkiw later redesigned the drum read electronics to use germanium transistors.

In 1964, CSIRAC was shut down for the last time. Its historical significance was already recognised at that stage, and it was placed in storage with plans for its later exhibition in a museum.

The machine was stored in a warehouse through the 1960s and 1970s, before being set up for exhibit at Caulfield Institute of Technology^[6] from 1980 to 1992. It was then returned to storage.

Interest in the machine was revived in the 1990s, as it was realised that many of its developers were aging and precious history was being lost forever. A conference about the machine was held in 1996.

The machine finally found a permanent home in the Melbourne Museum in 2000. It has not been operable since its shutdown, but many of the programs that ran on it have been preserved, and an emulator has been written for it. The curators have decided that, aside from the cost of restoring the device, that the huge number of repairs that would be required to make it safe to operate (CSIRAC used 30 kilowatts of power in operation) would detract from its historical authenticity.

CSIRAC is listed on the Victorian Heritage Register and is included a Heritage Overlay. ^[7]

Defining characteristics of some early digital computers of the 1940s (In the history of computing hardware)

Name	First operational	Numeral system	Computing mechanism	Programming	Turing complete
Zuse Z3 (Germany)	May 1941	Binary floating point	Electro-mechanical	Program-controlled by punched 35 mm film stock (but no conditional branch)	Yes (1998)
Atanasoff–Berry Computer (US)	1942	Binary	Electronic	Not programmable—single purpose	No
Colossus Mark 1 (UK)	February 1944	Binary	Electronic	Program-controlled by patch cables and switches	No
Harvard Mark I – IBM ASCC (US)	May 1944	Decimal	Electro-mechanical	Program-controlled by 24-channel punched paper tape (but no conditional branch)	No
Colossus Mark 2 (UK)	June 1944	Binary	Electronic	Program-controlled by patch cables and switches	No
Zuse Z4 (Germany)	March 1945	Binary floating point	Electro-mechanical	Program-controlled by punched 35 mm film stock	Yes
ENIAC (US)	July 1946	Decimal	Electronic	Program-controlled by patch cables and switches	Yes
Manchester Small-Scale Experimental Machine (Baby) (UK)	June 1948	Binary	Electronic	Stored-program in Williams cathode ray tube memory	Yes
Modified ENIAC (US)	September 1948	Decimal	Electronic	Read-only stored programming mechanism using the Function Tables as program ROM	Yes
EDSAC (UK)	May 1949	Binary	Electronic	Stored-program in mercury delay line memory	Yes
Manchester Mark 1 (UK)	October 1949	Binary	Electronic	Stored-program in Williams cathode ray tube memory and magnetic drum memory	Yes
CSIRAC (Australia)	November 1949	Binary	Electronic	Stored-program in mercury delay line memory	Yes

See also

• Electronic music
• Computer music
• SILLIAC Sydney University's first computer

References

Notes

1. ^ "CSIRAC: Australia’s first computer". http://www.csiro.au/science/ps4f.html. Retrieved 2007-12-21. 
2. ^ ^{a b} Fildes, Jonathan (2008-06-17). "Oldest computer music unveiled". BBC News Online. http://news.bbc.co.uk/1/hi/technology/7458479.stm. Retrieved 2008-06-18. 
3. ^ 6SN7 Double Triode, 8 pin, 3.8W heater
4. ^ 6V6 Beam Power Pentode, 8 pin, 2.8W heater
5. ^ KT66 Beam Tetrode, 8 pin, 8.2W heater
6. ^ http://museumvictoria.com.au/collections/items/761661/slide-csirac-computer-trevor-pearcey-1965-1975
7. ^ "CSIRAC, Victorian Heritage Register (VHR) Number H2217". Victorian Heritage Database (Heritage Victoria). http://vhd.heritage.vic.gov.au/#detail_places;114928. Retrieved 2010-09-16 

Bibliography

• Beard, M.; Pearcey T. (1984). "The Genesis of an Early Stored-Program Computer: CSIRAC". IEEE Annals of the History of Computing (IEEE) 6 (2): 106–115. doi:10.1109/MAHC.1984.10014. 
• Deane, John (1997). CSIRAC: Australia's first computer. Australian Computer Museum Society. pp. 45p. ISBN 0-6463-4081-6. 
• Doornbusch, Paul (2005). The Music of CSIRAC, Australia's first computer music. Common Ground. ISBN 1-86335-569-3. http://thehumanities.cgpublisher.com/product/pub.61/prod.10. 
• McCann, Doug; Thorne, Peter (2000). The Last of The First, CSIRAC: Australias First Computer. University of Melbourne Computing Science. ISBN 0-7340-2024-4. http://www.bookshop.unimelb.edu.au/catalogue/niagra.php?ITEMNO=9780734020246.  – A timeline and history of CSIRAC, as well as a collection of presentations from the 1996 conference on the machine.
• Pearcey, Trevor (1988). A History of Australian Computing. Chisholm Institute of Technology. pp. 192p. ISBN 0947186948.   —  An excellent history of computing in Australia, regrettably out of print and very scarce.

External links

• CSIRAC homepage – From the Computation Laboratory at the University of Melbourne's Dept of Computer Science and Software Engineering
• Australian National Treasure - CSIRAC – Television segment on CSIRAC
• The Computer 'CSIRAC' – 1965 film
• The Music Of CSIRAC – Paul Doornbusch's book review