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Dirty Gertie: The DRTE Computer

IP.com Disclosure Number: IPCOM000129804D
Original Publication Date: 1994-Jun-30
Included in the Prior Art Database: 2005-Oct-07
Document File: 15 page(s) / 54K

Publishing Venue

Software Patent Institute

Related People

LINDA PETIOT: AUTHOR [+2]

Abstract

This article gives an account of the design, construction, end programming of the Canadian DRTE computer, which possessed several unique features. It also describes some of the uses to which it was put. In the early 1950s an electronics laboratory, headed by the English- trained electronics engineer Norman Moody, was formed at the Defence Research Telecommunications Establishment (DRTE) of the Defence Research Board (DRB) of Canada on the Ottawa outskirts. The purpose of this laboratory was to build up a group of people experienced in the design and construction of electronic circuits using the recently developed transistor. An additional objective, not at all clear when the group was formed, was the acquisition of a usable digital computer. As a result, the first transistorized general-purpose computer designed and built in Canada was produced in the very early 1960s. This computer was unofficially called Dirty Gertie (considered by many to be undignified) because no one could think of a better name. This computer is of interest because it incorporated several novel concepts, including a new form of transistorized flip-flop, a hardware decimal-to-binary and binary-to-decimal (DBBD) converter, and a unique core memory.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

Copyright ©; 1994 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Used with permission.

Dirty Gertie: The DRTE Computer

LINDA PETIOT

This article gives an account of the design, construction, end programming of the Canadian DRTE computer, which possessed several unique features. It also describes some of the uses to which it was put.

In the early 1950s an electronics laboratory, headed by the English- trained electronics engineer Norman Moody, was formed at the Defence Research Telecommunications Establishment (DRTE) of the Defence Research Board (DRB) of Canada on the Ottawa outskirts. The purpose of this laboratory was to build up a group of people experienced in the design and construction of electronic circuits using the recently developed transistor. An additional objective, not at all clear when the group was formed, was the acquisition of a usable digital computer. As a result, the first transistorized general-purpose computer designed and built in Canada was produced in the very early 1960s. This computer was unofficially called Dirty Gertie (considered by many to be undignified) because no one could think of a better name. This computer is of interest because it incorporated several novel concepts, including a new form of transistorized flip-flop, a hardware decimal-to-binary and binary-to-decimal (DBBD) converter, and a unique core memory.

Transistor research

Moody, who had previous experience with digital counters, quickly began to assemble a small team and develop basic circuits. One of the first tasks of this group was the design of a transistorized flip-flop that incorporated two different types of transistors (one PNP, the other NPN). It became known as the PNPN flip-flop. Vacuum-tube flip- flops of the 1950s and 1960s were generally made, following the Eccles-Jordan symmetrical design, with two similar tubes, one of which was always in the conducting state at any given instant, giving a constant current flow through one of two different paths in the circuit. The PNPN flip-flop was, on the other hand, either completely on or completely off -- that is, it was either conducting or not conducting electricity, like a light switch (see Figure 1).

The circuit had a switching time of 0.2 microseconds, and its main advantage was that it had high current handling capacity that gave it the ability to drive at least five similar circuits.2 What was not appreciated at the time, however, was that if one used such a circuit to construct a binary register then, when it switched from containing all zeros to all ones, an inordinate load was placed on the power supply to accommodate the changed current draw. In 1993, Moody reflected:

  (Image Omitted: It had a fundamental fault. You can't really afford, when you're dealing with pseudorandom quantities, to have enormously changing loads on your power grid. PNPN being on or off, there is...