Example of NCP Address I'm looking to provide an example of an NCP (Network Control Protocol) address for a scholarly article that I'm writing. The NCP was the protocol that was used by the ARPANet and which was introduced in RFC 33. The RFC says that hosts were addressed using a 40 bit address with the first 24 bits identifying a user, the next 8 bits addressing a host and the final 8 bits being just 8 bits that the host could use however it liked to address a process on the machine (these were early mainframes after all!). I can't find any indication though of how people actually wrote these NCP addresses at the time and the only example in the RFC, X'0100050107', I can't quite figure out. Does anyone know how they were written/formatted? (Of course, I'm tempted to just write something like 192.192.192.192.82; but I'm concerned this would be an anachronism).

The ten-digit notation is hexadecimal, as indicating with the leading _X_. Each hexadecimal digit represents four bits - ten digits of four bits = 40 bits.