The acronym 4B indicates the second digital signal processor designed by Italian physicist Giuseppe Di Giugno at Ircam in Paris.

Brief History – After developing the 4A, between Naples and Paris, Peppino Di Giugno start working immediately to the 4B; the first realized entirely at Ircam, the research center directed by Pierre Boulez, that open the activity exactly in these years. The 4B project was made with a collaboration of Hal Alles, that moved to the Ircam together with Max Mathews by Bell Labs. Even Alles, at Bell Labs in 1977, had worked to a digital synthesizer, as Di Giugno in Europe.

Technical features – The work for the 4B finished in 1977. According to the guidelines of this project, the 4B will have been interfaced with a DEC LSI-11 microcomputer, managed via OS installed on a floppy disk, so the 4B would have worked in real time. All the system was equipped with a memory that, thanks to the LSI-11, allowed users to save and recall data and so they were able to use not only fixed waveforms but also arbitrary. In particular, the speed of calculation of the 4B allowed the simultaneous use of 4 different waveform.[1] We remind that the 4B was equipped with 4 DAC and 64 oscillators for each, so for a total of 256 oscillators. The 4B processor permitted even the Frequency Modulation synthesis.[1]

Real Time/Deferred Time – Although designed for real time performance, as we noticed early, the 4B digital processor could run even in deferred time, in this way the composers could take advantage by software still powerful but not implement for real time, such as the famous Music V, moreover available at Ircam.[1]

Control Software – Previously we have noticed also that the 4B had four DAC as output, but we must say also that it had not ADC to import audio samples.[2] For this, a control software named Syn4B was developed at Ircam by Philippe Prévot e Neil Rolnick.


For this topic I’ve read:

[1] Hal Alles, Giuseppe Di Giugno, The 4B: A One-Card 64-Channel Digital Synthesizer in Foundations of Computer Music, A cura di Curtis Roads e John Strawn.
[2] Neil Rolnick, A Composer’s Notes on the Development and Implementation of Software for a Digital Synthesizer in Foundations of Computer Music, a cura di Curtis Roads e John Strawn, The MIT Press, 1988.
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