From Computer History Museum:
We are releasing scanned printer listings and/or machine-readable source code for four early versions of CP/M dating from 1975 to 1979. Some versions are incomplete, but please don't ask us for what is missing because we are releasing everything we have.
This material is provided for non-commercial use only. All the files are combined into one ZIP file with four directories representing the four versions.
The zip file is a 170MB download.
Although my first (and longest job) was with Burroughs/Unisys mainframes, CP/M was the OS of choice at university back then (early and mid-80s), actually the MP/M version.
Good memories.