The Australian built automatic computer, initially known as the CSIR Mk1 and later known as CSIRAC, was one of the world’s earliest stored program electronic digital computers. Developed in Sydney in the late 1940s by the Council for Scientific and Industrial Research (CSIR), the CSIR Mk1 ran its first program in November 1949. Trevor Pearcey, an English radio physicist, and Maston Beard, a researcher at the CSIR Radiophysics Laboratory in Sydney designed the CSIR Mk1. The first ‘programmer’ or real software engineer to work with the CSIR Mk1 was Geoff Hill, a mathematician who assisted with the logical design. Hill, who came from a musical family, programmed the CSIR Mk1 to play popular musical melodies from the very early 1950s. In 1951 the CSIR Mk1 publicly played the tune Colonel Bogey. The CSIR Mk1 was moved to Melbourne in June 1955 and renamed CSIRAC. In Melbourne, the mathematics professor Thomas Cherry programmed CSIRAC to perform music and developed a system and program such that anyone who understood standard musical notation could create a punched paper data tape for CSIRAC to perform that music. The music performed by the CSIR Mk1 may seem crude and unremarkable compared to the most advanced musical developments of the time and with what is possible now, but it is amongst the first computer music in the world and the means of production was at the leading edge of technological sophistication at the time. These first steps of using a computer in a musical sense occurred in isolation and they are interesting because it is the leap of imagination to use the flexibility of a general computer to create music and the programming ingenuity required to achieve that which is significant. CSIRAC took some initial steps in that direction.