Here is my list of interesting reads about the HP 9100.
The 9100 Project
This web site tells the story of the HP 9100. Excellent, a must read!
9100A desktop calculator
HP 9100A on HP’s virtual museum.
The Museum of HP Calculators
Lots of nice pictures and information about the HP 9100, including technology, programming, and more.
HP Computer Museum
One of the best resources for vintage HP computing.
The Italian Museum of HP Calculators
One of the jewels in this collection is a very nice HP 9100A and an HP 9160A Marked Card Reader.
HP 9100 Programmable Calculator
Web site of another HP 9100 enthusiast.
Computer Asylum / HP 9100B
Nice pictures of the 9100B assembly and parts (link broken, any information welcome).
HP-9100A Complete Teardown
Even more nice pictures of all the innards.
HP Calculator Patents
United States Patents regarding HP calculators, including the HP 9100.
Moon Landing Simulator for the HP 9100
The famous game, enjoy!
HP 9100B on Flickr
Pictures of my own HP 9100B system.
Computer Structures: Readings and Examples
G. Gordon Bell and Allen Newell, 1971 by McGraw-Hill, Inc.
Chapter 20 is about the HP 9100A calculator.
Computers Changed History
A Timeline of how computers changed history.