There was significant activity in electronic music before the development of the CSIR Mk1 and before the more experimental and adventurous musical developments after World War II. At about the turn of the century, Thaddeus Cahill created the first major electronic instrument, the 'Telharmonium'. In Moscow, Leon Theremin developed an instrument that was played by the performer moving his hands near two antennae. Throughout the 1920’s and 1930’s, many other electric and electronic instruments were developed such as the ’sphärophon', the 'Dynaphone', the 'Ondes Martenot' and the 'Trautonium'. CSIRAC had a similarity to most of these instruments in that it was also used to play traditional instrumental music, and like many other instruments, it could do more.

There were other developments at this time that used electronics, which took a fresh and less musically restrictive approach to both sounds and music itself. Percy Grainger, after writing 'Free Music' for theremins and because of his interest in free music, developed his own electronic musical instruments with the assistance of Burnett Cross. Similarly, Huge Le Cain’s 'Coded Music Apparatus' also allowed control of sound synthesis by visual curves.

Most early electronic musical instruments were used to play electronic renditions of standard repertoire and not to create new music. The real history and legacy of electronic music comes from developments which happened at about the same time that CSIRAC was being planned and built. Against the background of the great artistic expansion, the spirit of freedom, reconstruction and liberation artists felt after World War II, electronic music blossomed. There were two significant emerging developments. 'Musique concrète', where music is created with recorded sounds, was establishing itself in the late 1940s through the activities of Pierre Schaeffer and Pierre Henry. Analog electronic music was the other area of intense interest where, as distinct from musique concrète, sounds are generated purely by electronic means, using oscillators, filters and so on. Some of the main composers who pioneered this work are Gottfried Michael Koenig, Karlheinze Stockhausen, Karel Goeyvaerts, and Herbert Eimert. Such musical developments were dependent on the available technology of electronic oscillators, filters and tape recorders.

In addition, at the time CSIRAC was being designed and built, John Cage, Pierre Boulez and others were writing advanced instrumental music, developing new composition theories and becoming interested in electronic music. Against this background, but in isolation, CSIRAC first played music. While the musical output of CSIRAC was unimaginative compared to many of the musical developments emerging during its early years, there was considerable imagination required to use a general computing machine to play music and there was a great deal of ingenuity required to devise the techniques and programs to play it.

From a computing perspective, it is not simple to put activities into historical context. There is a problem of definition - what combination of hardware and software capabilities constitutes a computer? Charles Babbage created some early mechanical calculators. Konrad Zuse created some early electromechanical calculators and his Z3 of 1941 has been called the first electromechanical programmable calculator. Alan Turing’s 'Colossus' was operational in 1943 and it has been called the first all-electronic programmable calculator as it had no memory and was driven by a punched paper tape. ENIAC was designed as a calculator but was later given programmable control. Eckert’s SSEC, in 1948, was a configurable calculator which could execute programmed instructions. This list could continue and fill several volumes. (There are some internet references here.) However, if one accepts the general definition of a digital computer as an all-electronic device capable of calculating and branching operations, where the data and instructions are held in some sort of rewritable memory, then the following series of events is an approximate guide to when the first all-electronic digital computers ran their first test programs.