I have this:
A Pocket Guide to Hewlett Packard Computers (early/mid '70s?)
covering the 2116B, 2115A, and 2114A sections:
Specifications and Basic Operation Manual
Assembler Reference Manual
Basic Control System Reference Manual
Fortran Reference Manual
Program Library Reference Manual
BASIC Language Reference Manual
Most of these have been scanned and OCR'd and can be found at
Jeff Moffat's site:
http://oscar.taurus.com/~jeff/hp2100
(that's typed from memory, may be wrong).
Of course, someone who has actual hardware might want actual
books; since all I've got are simulators, reasonable facsimilies
are OK.
Regards,
-dq