Binary keypad front panel

Eric Smith spacewar at
Fri Mar 3 14:46:12 CST 2017

On Mar 3, 2017 12:58 PM, "John Wilson via cctalk" <cctalk at>
> It occurred to me that lots of old machines had binary front panels
> (switches and lights) and lots of machines had keypad front panels (octal
> or hex, with 7-segment LEDs), but I'd never seen a binary keypad front
> panel.

It wasn't a computer, but the first commercial frequency-synthesized
scanning receiver, the Tennellec Memoryscan, circa 1974, used a binary
keypad. It came with a fat book listing a 16-bit binary code for each
frequency the scanner could receive. You could program up to 16 such codes
into the scanner.

My grandfather bought one for my grandmother when I was 10 years old, and I
was put in charge of programming in the codes for the frequencies my
grandmother selected. Since I already new binary, I worked out formulas for
the codes so that I wouldn't have to use the book. That way I could program
the scanner in only ten times the time.

It did come in handy some years later when my grandmother wanted to changes
the frequencies, but the code book had been lost.

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