The Hewlett-Packard HP2100A minicomputer.
I used such computers in high school from 1971 to 1975. The model contained 8K words (16K bytes) and ran a BASIC interpreter.
About 10 years later I acquired two of these minis fully loaded with 64K bytes (one was an HP2100S version - containing floating point support) as well as an ASR-33 teletype, magnetic tape deck, paper tape reader, card reader, and drum printer. Unfortunately I had to give them up because the storage fees were becoming burdensome.
See my collection here. Sadly I no longer have anything.
I retained a soft spot for programming using the front-panel switches and writing in machine language.
In 2002 I started writing an emulator in C. Several interesting programming ideas came out of that. That was not completed.
I think this minicomputer was the perfect computer.
In the mean time enjoy the animated GIF screen grab below. The emulator is running a "light blinking program". I've written many such programs for recreation and to make the computer look more "Hollywood". After all, computers are supposed to do something.
As an aside, a similar light blinking program was implemented in 1981 on a Tandem T/16 super mini computer system while I was taking courses at the Tandem Computers Inc. corporate office in Toronto. After the initial shock it delighted the technicians, instructors and staff so much that they asked for my permission to have the program remain running on their flagship demo system. This was viewable from their lobby through a big glass wall to impress customers!
Revised 3 Oct 2015