## HP9100B

My “first” computer experience.
It was a high school class, “man made world”, which got me interested in computers. Before that I was interested in Science, but mostly in math.
This class taught logic with relays, and control with an analog computer. We also learned Fortran by punching cards on an IBM 26 keypunch. Those decks of cards would go into an inter-office envelope and wander its way to the central school computer; where, later, a printout would be sent back in the same slow way.
Printer Art was the fashion then, and I printed Fonebone from Mad Magazine, and a portrait of a schoolmate, but mostly did Spirographs.
When I got into a higher math class there was a programmable calculator with a plotter. It was an HP9100B. You can see an HP9100 in the original movie “The Andromeda Strain”. The van finding the plane crash plots the triangulation with the HP9100 and plotter. In the movie it is not model HP9100B as the keyboard was slightly different between the revisions.
In free time, I had access to the calculator where I made Spirographs and Random Duckies and Vector Art and Letters.

Logic with relays used an AMF Logic Circuit Board Model 800.  It has 4 switch inputs, 4 relays, and 4 output lamps.  We used it mostly to make noise and blinking lights.  However, I once programmed it for a combinations lock, where the sequence of flipping switches enabled one relay to latch, then another — until you got all 4 relays to latch (without all clearing with a wrong switch flip) and then light a lamp.

Analog control used an AMF Educational Computer Model 665/D.  It has an integrator, differentiator, 2 mixers, and knobs.  We used it mostly to make circles or watch exponential decay.  I figured out how to use a diode to take the maximum between a Sin and Cosine wave, put that on the display Y axis, then combine the Sin and Cosine on the X axis to make a Heart.

At one point, a few enthusiastic students of the class visited the school district computer.  Not much to see, a big iron box here, another big iron box there…  I asked how large the accumulator was, the answer being “32 bits”.  What I actually wanted to know was physical size.  I suspect it would have been multiple boards, but we never got to peer inside the cabinets.  But: *** now I get to peer inside of cabinets ***