MUSYS. Peter Grogono, United Kingdom, 1969

EMS was the London electronic music studio founded and run by Peter Zinovieff in 1965 to research and produce experimental electronic music. The studio was based around two DEC PDP8 minicomputers, purportedly the first privately owned computers in the world.

One of the DEC PDP8 mini-computers at EMS
One of the DEC PDP8 mini-computers at EMS

Digital signal processing was way beyond the capabilities of the 600,000 instructions-per-second, 12k RAM, DEC PDP8s; instead, Peter Grogono was tasked with developing a new musical composition and ‘sequencing’ language called MUSYS. MUSYS was designed to be an easy to use, ‘composer friendly’ and efficient (i.e. it could run within the limitations of the PDP8 and save all the data files to disk – rather than paper tape) programming language to make electronic music.  MUSYS, written in assembly language, allowed the PDP8s to control a bank of 64 filters which could be used either as resonant oscillators to output sine waves, or in reverse, to read and store frequency data from a sound source. This meant that MUSYS was a type of low resolution frequency sampler; it could ‘sample’ audio frequency data at 20 samples per second and then reproduce that sampled data back in ‘oscillator mode’. MUSYS was therefore a hybrid digital-analogue performance controller similar to Max Mathew’s GROOVE System (1970) and  Gabura & Ciamaga’s PIPER system (1965) and a precursor to more modern MIDI software applications.

“It all started in 1969, when I was working at Electronic Music Studios (EMS) in Putney, S.W. London, UK. I was asked to design a programming language with two constraints. The first constraint was that the language should be intelligible to the musicians who would use it for composing electronic music. The second constraint was that it had to run on a DEC PDP8/L with 4K 12-bit words of memory.”

The two PDP8’s were named after Zinovieff’s children Sofka (an older a PDP8/S) and Leo (a newer, faster a PDP8/L). Sofka was used as a sequencer that passed the time-events to the audio hardware (the 64 filter-oscillators,  six amplifiers, three digital/analog converters, three “integrators” (devices that generated voltages that varied linearly with time), twelve audio switches, six DC switches, and a 4-track Ampex tape-deck). Leo was used to compute the ‘score’ and pass on the data when requested by Sofka every millisecond or so;

“These devices could be controlled by a low-bandwidth data stream. For example, a single note could be specified by: pitch, waveform, amplitude, filtering, attack rate, sustain rate, and decay time. Some of these parameters, such as filtering, would often be constant during a musical phrase, and would be transmitted only once. Some notes might require more parameters, to specify a more complicated envelope, for instance. But, for most purposes, a hundred or so events per second, with a time precision of about 1 msec, is usually sufficient. (These requirements are somewhat similar to the MIDI interface which, of course, did not exist in 1970.)”



Previous to the development of MUSYS, the EMS PDP8s were used for the first ever unaccompanied performance of live computer music ‘Partita for Unattended Computer’ at Queen Elizabeth Hall, London, 1967. Notable compositions based on the MUSYS sytem include: ‘Medusa’ Harrison Birtwistle 1970, ‘Poems of Wallace Stevens’  Justin Connolly. 1970, ‘Tesserae 4’  Justin Connolly 1971, ‘Chronometer’  Harrison Birtwistle 1972, ‘Dreamtime’ David Rowland 1972, ‘Violin Concerto’  Hans Werner Henze 1972.

Audio Examples

Demonstrating the digital manipulation of a voice with the frequency sampler:

In the Beginning‘ PeterGrogono with Stan Van Der Beek 1972. “In 1972, Stan Van Der Beek visited EMS. Peter Zinovieff was away and, after listening to some of the things we could do, Stan left with brief instructions for a 15 minute piece that would “suggest the sounds of creation and end with the words ‘in the beginning was the word'”. All of the sounds in this piece are derived from these six words, heard at the end, manipulated by the EMS computer-controlled filter bank.”

Datafield‘ Peter Grogono 1970

Chimebars  Peter Grogono 1968

 MUSYS code examples

A composition consisting of a single note might look like this:

      #NOTE 56, 12, 15;

The note has pitch 56 ( from an eight-octave chromatic scale with notes numbered from 0 to 63), loudness 12 (on a logarithmic scale from 0 to 15), and duration 15/100 = 0.15 seconds. The loudness value also determines the envelope of the note.

An example of a MUSYS  program that would play fifty random tone rows:

      50 (N = 0 X = 0
      1  M=12^  K=1  M-1 [ M (K = K*2) ]
         X & K[G1]
         X = X+K  N = N+1  #NOTE M, 15^, 10^>3;
         12 - N[G1]

MUSYS evolved in 1978 into the MOUSE programming language; a small, efficient stack based interpreter.


Peter Grogono.’MUSYS: Software for an Electronic Music Studio. Software – Practice and Experience’, vol. 3, pages 369-383, 1973.

The ‘PIPER’ System James Gabura & Gustav Ciamaga, Canada, 1965

Charles Hamm, Lejaren Hiller, Salvatore Martirano, Herbert Brün, Kenneth  Gaburo at the EMS, Toronto, 1965
Charles Hamm, Lejaren Hiller, Salvatore Martirano, Herbert Brün, James Gaburo at the EMS, Toronto, 1965

PIPER was one of the earliest hybrid performance system allowing composers and musicians to write and edit music in real time using computers and analogue synthesisers. The system was developed by  James Gabura & Gustav Ciamaga Who also collaborated with Hugh Le Caine on the ‘Sonde’) at the University of Toronto (UTEMS) in 1965. With computing technology in 1965 being to weak to synthesise and control sounds in real-time a work-around was to leave the scoring and parameter control to the computer and the audio generation to an external analogue synthesiser. The PIPER system consisted two Moog oscillators and a custom built amplitude regulator to generate the sound and an IBM 6120 to store parameter input and to score the music. The computer would read and store the musicians input; keyboard notes, filter changes, note duration and so-on and allow the user to play this back and edit in real-time.

By the 1980’s such large hybrid analogue-digital performance systems like PIPER and Max Mathew’s GROOVE were obsolete due to the advent of affordable, microcomputers and analogue/digital sequencer technology.