Hi Dieter,

> MM5837 data sheet (digital noise source)
> Digital Noise Generator of the Formant Synthesizer (Book Elektor

Verlag,

> ISBN 3-921608-19-8, 1981, pages 24-25)
> Digital Noise Generator published in the magazine Elektor about

1978/1979

Thanks for those pointers - I found that book online, and through it
discovered the circuit is used in quite a few others places: the ETI
3800, 4600 & 5600, and it is also mentioned in Barry Klein's book
too, though unfortunately none of these give any decent analytical
treatment of it. However I finally managed to work through most of
the theory myself, to the point where I could deduce the period as
2^18-4, so agreeing with the brute-force calculation of the whole
sequence. If anyone is that interested, I gave the bare-bones of it
on the Synth DIY list, available in the archives here:

http://search.retrosynth.com/synth-diy/search/lookit.cgi -v0805.169

Tim