PU-104 was a key generator for perforated paper tape, made around 1986 by Rohde & Schwarz (R&S) in München (Munich, Germany). The device was able to create long sequences of truly random numbers and send them to external paper tape puncher via its built-in V.24 interface.
I'm trying to understand how random noise was sampled by the CPU. I don't think that they used an dedicated analogue to digital converter, but rather went directly from analogue to digital logic. I can't follow what happens after the noise enters the purple square in the following schematic extract:-
The extract is from the complete user manual at https://www.cryptomuseum.com/crypto/rs/pu104/files/pu104s2_manual.pdf. See pages 24-27 of the PDF file. The 'bottom' board photograph clearly shows two PM156 op-amps which I cannot locate on the schematics. They're not of a style I'm accustomed to.
It don't know why there are two schematics.