I own two HP minicomputers, an older HP 2114B, with core memory, and a newer 1000 M Series HP 2112B, with semiconductor memory. The book, pictured below, belonged to me when I took Computer Science 436 at the University of Wisconsin one summer, which employed an HP 2114B. Towards the end of that course, I wrote an emulator for the HP 2114B CPU.
The HP 2114B
I acquired my HP 2114B, along with a couple of paper tape readers and an HP 2780A Disk Drive from a gentleman near Eau Claire, WI, who had rescued them from an ignominious end in a dumpster. I had the HP 2114B running, at one point (and it might even still work), but the disk drive does not work (yet). An interesting feature of the HP2114B is the switch used for address and control. Rather than the more typical lever / toggle switch arrangement, it uses capacitive touch switches, with embedded lights and a little audible clicker for touch feedback.
At the bottom of the rack you can see my HP 2748A paper tape reader. I also have a separate HP2748B paper tape reader.
I have lots of software for this machine on paper tape.
The HP 1000 M Series 2112B
The HP 2112B’s arrival in the collection was the result of a trade. (You can visit the Data General page to read the story). This computer is quite similar to the HP 2114B. Like most of the machines in the collection, this one still works (or at least did when I last tried it). However, I am short of peripherals and controllers for it — please see my wish list.