> Hi Silas,
>
> Well three of us have arrived at that figure independently, so I'm
> reasonably confident it is good. I have now also checked it against
> the 19-stage linear FSR equivalent, and that agrees too. Since I *do*
> have the polynomial for the 19-stage sequence, I'm working on how to
> derive the sequence length analytically, but it is taken a while to
> get back up to speed - it was about 10 years ago I last looked at all
> this stuff.
>
> The circuit is very interesting, as whilst it is certainly not a
> linear FSR in the usual sense (I can't work out if it is non-linear
> or just 'inhomogeneous', but in either case, most of the established
> theory will probably not be applicable), it very capably produces a
> good long sequence, and does not need any special circuitry to kick-
> start it into action (the inverter in the feedback loop sees to that).
>
> So far I've tracked it down to 3 other places:
>
> - Ken Stone's CGS Digital Noise (probably later than the A-117)
> - A book by Ray Marston: 'Integrated Circuit and Waveform Generator
> Handbook' (1990)
> - and the Transcendent 2000 (circa 1978 )
>
> I suspect it is originally from some short paper published ages ago
> (perhaps in something like 'Electronics Letters') - I just wish I
> could track the exact reference down, and save me probably a deal of
> work!
>
> Tim

Some other interesting places may be:

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 (I
have to find out the exact issue if you are interested, it was the basic
circuit for the Formant digital noise)

Best wishes
Dieter Doepfer