Syn4B is a control software for the 4B digital signal processor. It was developed by Philippe Prévot and the composer Neil Rolnick at Ircam, Paris, in the late seventies.
Brief History – After developing the 4B, it became clear that there was need of a control software for managing the DSP by Giuseppe Di Giugno. The Syn4B was designed for these goals, and to make the 4B the most powerful computer system for real time music composition and performance. Since the 4B was interfaced with a DEC LSI-11 microcomputer, also the Syn4B was programmed with the same assembler.
System Management – It must be said that the Syn4B was designed to work not only with the 4B, but also with the entire system, so to control the DEC LSI-11 memory, or to put in connection the 4B processor with others external controllers; all this in real time.
Open Design – According to researchers, one of the most important aims of the Syn4B had to be his open design, so to contain future developments and to limit a rapid obsolescence. Even for this, when the project 4B was closed to encourage the new 4C processor, Philippe Prévot tried to adapt the Syn4B to the new DSP, although afterwards he preferred develop the 4Ced.
Software Management – Beyond the future, the Syn4B could be management with text files and a teletypewriter. There wasn’t a graphic environment, so the Syn4b was realized as the Music N model: an alphanumeric approach and text files. The researchers tried to simplify the syntax to make more easy the use of the software. But several limitations exist for interact with the 4B.
Interact with 4B – Initially, the 4B was designed with two different approach: the first was the alphanumeric approach, based on Music N model. Another one wasn’t realized, because the 4B was rapidly retired.
Limits – All this, help to understand how limited was the Syn4B and, consequently, the 4B processor. In fact, even Neil Rolnick has underlined as this limited features of the Syn4B have pushed the research activity towards a new project that was called 4C, developed in 1978.
 Neil Rolnick, A Composer’s Notes on the Development and Implementation of Software for a Digital Synthesizer in Foundations of Computer Music, edited by Curtis Roads and John Strawn, The MIT Press, 1988.
 Gerald Bennett, Research at Ircam in 1978, Rapports IRCAM 1/78, Centre Georges Pompidou, Parigi, 1978.