I have scans of the manuals listed below. All the manuals, MU5 and its software are the work of the University of Manchester. They are made available with permission, but must not be used for gain or profit.
MU5 Hardware Manual Volume 1. This manual covers the various parts of the CPU and memory. Download (BitSavers).
MUSS User Manual. This scan probably dates from around 1980. Download.
MUSS User Manual. Issue 10. This one seems to be a later edition than the one above, dating to around 1982. It was printed by Sperry Univac because they appear to have licensed MUSS, possibly for embedded systems relating to chip design. Download.
MUSS Basic Library Manual Volume 2. Part 1. Download.
MUSS Basic Library Manual Volume 2. Part 2. Download.
MU5 MX3 High Level Languages Manual. 2nd Edition, July 1974. This manual covers MU5 Algol 60, MU5 Fortran, MU5 Atlas Autocode, MU5 Autocode and MX3 Algol 60. Download.
MUSS Languages Manual Volume 2. Issue 12. This manual covers Fortran 77, Pascal, Basic and C. Download.
MUTL Manual. This manual describes the Manchester University Target Language, which is an intermediate language for compilers. Download.
MUSS Volume 1. A manual to assist those involved with the implementation of MUSS. Volume 1 is just for the basic operating system.Download.
The MU5 Compiler Writers Manual. July 1974. Download.
The MUPL Programming Language. September 1979. This manual describes the programming language used to implement initial versions of MUSS, later versions were mostly implemented in MUSL. MUPL is described in the Morris and Ibbett book as a “cleaned up Autocode”. Download.