Earlier quoted context omitted.
The oldest parts are not System 360, they run IBM 7074 assembly. Just FYI. The caching system is much newer, they have some Java proxy, there were posts about it the last year.
The manual for the 7070, which was similar, is here: http://www.bitsavers.org/pdf/ibm/7070/A22-7003-01_7070_Refer... The instruction set documentation starts at page 42.
The manual... and it's less than 300 pages... oh boy, I remember the System 3090 manual, it was several metres thick :D (in several volumes, of course)