Desk Electronic Calculators

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Monroe Epic 3000

Monroe Epic 3000

Litton Monroe Epic 3000 keyboard/printing unit and calculating unit.

Monroe Epic 3000

Electronic calculator made by Monroe in USA, introduced in 1967, serial number B996581.

Performs the standard 4 functions & square root, and is programmable.
When switched to learn mode it remembers up to 42 steps of calculation, so that thereafter all control key selections are automatic.

Display - printed output.

Size - Keyboard/printing unit - (12.5" x 17" x 9"), Calculating unit - (20" x 5" x 22").

Weight - Keyboard/printing unit - (30 lbs), Calculating unit - (30 lbs).

Made in USA, introduced 1967, and was advertised as the "First Programmable Printing Calculator", though there were previous non-printing programmable calculators (such as the Wang models and the Olivetti Programma 101).

Technology - Uses individual transistors (mainly RCA 581005B & 581024B transistors) on four boards 355 mm x 350 mm (14" x 14"), one of which has 2 delay-line memories.

Monroe produced high quality, high capability mechanical and electro-mechanical calculators. By this time they were owned by Litton Industries. Calculators like this were soon out-moded by the use of Large-Scale Integrated-Circuits (LSI)..

There were several other programmable calcuators before this one, including ones by Wang and Olivetti.

"Data and Control Systems" for October 1966 gives the following details of the Epic 2000 (lower specification model) -
"Performs an average division operation in 1/4 of a second; multiplications take 1/3 of a second; 16-digit or single-digit figures are handled at the same speed. Addition and subtraction take 1/125 of a second; square roots take 1/2 second."


Advertisement for the Monroe Epic 3000 from 1967.

"Photographed at NORAD, Colarado Springs"

"Beautifully efficient: The new Epic 3000 Electronic Printing Calculator"

"The only electronic calculator that is operator programmable. Simply push a learn button, do a problem once, and the Epic is programmed to automatically repeat similar arithmetic functions on other problems. Insures accuracy and saves time. Finds square roots in just a half second. Line by line results are printed on tapes that provide a permanent record and can be checked at any time."

Note that no mention is made of the large electronics unit.

The keyboard/printing unit.

Keyboard/printing unit

The keyboard/printing unit with cover removed.

Calculating unit with cover removed

The calculating unit with cover removed and 2 of the 4 boards hinged down for servicing.

Delay-line memory

One of the circuit boards with a delay-line memory which has been opened up, showing the 2 memories.

Delay-line memory close up

Close-up of one of the delay-line memories.

Click here to go to the page describing delay line memories.

Circuit board

One of the circuit boards.

Size 355 x 345 mm (14 x 13.6 ins).

Circuit board detail

Circuit board detail.

Transistors - RCA 581005B & 581024B.

The circuit boards have copper conductors on one side only. The red wires are enamelled copper wire which provide additional connections.

Vintage Calculators

© Text & photographs copyright Nigel Tout   2000-2015 except where noted otherwise.