Friden 132 calculator

Friden Model 132 electronic CRT calculator
Manufacturer: Friden
Original Price: $1950 - Original Date: 1964


Photo of  Friden 132 calculator

As reported by Nicholas Bodley, its circuitry was totally discrete, using germanium
transistors and discrete diodes. The internal storage was by ultrasonic delay line.

Internal digits were represented in one of two ways: On the delay line, really simply,
by pulses within a specific time slot allotted to that digit. A number six, for instance,
was represented by six consecutive pulses. Within the electronics proper, a digit was
represented by a nonweighted 5-bit binary code that corresponded to the states in a
Johnson counter (also called a "switch-tail ring counter"). This is simply a 5-bit shift
register with its serial output connected back to its serial input with a Mobius-strip-like
"half-twist". The counters in the EC-13x calcs. had parallel input and output as well.

The code itself looked like this: 0 00000, 1 00001, 2 00011, 3 00111
4 01111, 5 11111, 6 11110, 7 11100, 8 11000, and 9 10000

The keyboard digits were mechanically coded internally this way. This machine
had no adder or arithmetic unit in the usual sense; it did its
arithmetic by counting pulses as they came out of the delay line.


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