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Virtual Museum > The electronic revolution > CRT Display
In 1968, Hewlett-Packard Company announced a new product that will become almost a legend in the calculator world: the HP9100A.
Here is the announcment in the HP Journal of September 1968


The HP9100A was the equivallent of a large size computer in a small footprint, small enough in fact to fit on a regular desk top.


As you can see on the picture above, the machine was constructed as a "tank", with a very sturdy aluminium case, and a large size keyboard to easily enter all the numbers and functions. The display was using a CRT (Cathode Ray Tube), which was not really unusual at that time, because this technology was well understood for television, and easily applicable to computers.

The keyboard was also very well organized, depending on the functions:


On the left, all statistical or geometric functions: Sin, Cos, ex, ln(x) , log(x), etc...

On the middle left, computer related functions including the hexadecimal letters (a through f). The arrow keys were used to move content in the specific registers.

On the middle right, the standard number keyboard with 4 basic operations and square root

On the right, comparison functions used for programming

Yes, this was a programmable computer, and you coould even write your program on a small magnetic card. Then you could retrieve it later and read it from this card using the card reader on the top of the keyboard. This card reader was manual, meaning that you had to push and pull the card yourself. This was a good method and avoided the later problems they had on the HP41, with the gummy wheel or slow motor.

But the really surprising thing when you open such a calculator, is that there is no Integrated Circuit used, only discrete components: Diodes, transistors, resistors, etc. The most interesting board is the backplane, which is only a collection of hundreds of diodes and resistors, as you see on the picture below:


closer view



The rest of the boards were mainly flip-flops, and a big core memory board to keep the data in memory.

(more details about the one I own)

See below a small video to describe the one I was able to acquire recently.
This page has been seen times since August 2015
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