The world's first computer-controlled music was generated in Australia by programmer Geoff Hill on the CSIRAC computer which was designed and built by Trevor Pearcey and Maston Beard.
All MUSIC-N derivative programs have a (more-or-less) common design, made up of a library of functions built around simple signal-processing and synthesis routines (written as "opcodes" or unit generators).
In this aspect, Csound and RTcmix have since evolved to work effectively as software libraries which can be accessed through a variety of frontends and programming languages, such as C, C++, Java, Python, Tcl, Lua, Lisp, Scheme, etc., as well as other music systems such as Pure Data, Max/MSP and plugin frameworks LADSPA and VST.
A number of highly original (and to this day largely unchallenged) assumptions are implemented in MUSIC and its descendants about the best way to create sound on a computer.
Prior to the advent of low-cost digital audio gear in the late 1980s, the samples were typically sent to a DAC and recorded on analog tape.