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Monroe EPIC 3000 Technology

From a technology perspective the EPIC 3000 is a machine of two parts, electronic and mechanical, future and past.


EPIC 3000
EPIC 3000

The electronic part uses Ge transistors for DTL logic and a magnetostrictive delay line for memory.

The EPIC machines featured learn-mode programming, where a series of keystroke steps could be memorised and then recalled to be run in the same sequence with different inputs. There were no test, branch or loop facilities other than arranging for the sequence to loop from the final instruction back to the first. Programs were lost at power-off, there was no facility to store or reload programs.


The electronic logic is built into a slim and stylish floor case. Three large boards carry most of the logic and a fourth board holds the magnetostrictive delay memory. The electronic construction is unusual, with large boards that are semi-permanently wired into a backplane. Field service by board-swapping would not have been easy. The construction of each board is also unusual, they are single-sided and have dense on-board interconnectons with lacquered coppper wires.


EPIC 3000
The interconnects are impossible to trace but fortunately there is a detailed silk screen. This gives signal names at each end of all interconnects and also names board edge test points and signals going off-board. At first sight the copper interconnects looked like an impossible reverse-engineering task but with the silk screen tracing will not be difficult and the signal names may make reverse engineering the circuit less difficult than usual.





EPIC 3000
EPIC 3000
The keyboard and printer are a stark contrast and show Monroe’s established skill in mechanical design and confidence in the production of complex mechanisms. Today it appears anachronistic to see complex mechanicals married to electronics but in the early 1960s this outcome may have arisen in a quite logical manner:

  • Printed results may have been a design requirement and a specific selling point. Financial users often wanted a printed audit trail and others may have appreciated the printout as a means to check on a new technology that my not have been fully trusted.
  • If printed results were an essential part of the brief, then the only options were to use a large teletype-style keyboard and printer or to develop a small bespoke machine
  • The decision for a bespoke unit may have been eased by Monroe being readily able to design and produce such a unit in-house.

For the collector, this is a very good outcome because the EPIC machines are uniquely interesting and special.

Uniquely challenging also, because all technical and service documents have been lost. While the silk screens on the circuit boards provide a way to solve the copper wire interconnects, there are no such assistances to help to understand how the mechanical parts work and how they may need to be adjusted or repaired.