EDDA 3 - Introduction

Parent Category: Articles Category: EDDA 3 - An Early Transistorized Process Computer Written by Administrator

The name EDDA means "Elektronische Digitale Datenverarbeitungs-Anlage" (electronic digital data processor).

EDDA is a process computer from 1969, used for control of production plants. It was designed as low-price device to fill the gap between hard-wired process control and small computers. The processor core is weak, but a large amount of peripherals could be connected. For enhanced reliability permanent self-checking was built in, with switch over to a backup machine in case of error. A large application was control of the cargo sorting system at the Frankuft airport in the early 1970s.

Function and architecture have similarities to early microcontrollers (e.g. PIC1640 from 1976), the design, however, is not "single-chip" but - typical for that period - “wall unit”.

The original manual is attached below.

Uncommon are the decimal representation of addresses and data as well as the internal number-serial data processing - today this is particularly known by the ENIAC. Also tricky is a shift register based on core memory, being implemented with minimal effort by using double wire wrap of cores.

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The EDDA 3 had a flexible architeture and could be expanded with memory and multiple I/O components.

system schema

(Typical components where: "Tastatur" = key board, "Waage" = scale, "Schreibmaschine" = type writer, "Elektromotor" = electric motor, "Programerweiterung " = expansion program memory, "Zusatz-Kernspeicher" = expansion core memory, "Ziffernanzeige" = digit display, "Zähler" = counter.
"Zusätzliche Zwischenelektronik" means "Additional interface circuits")



The concept dates from 1965; predecessors were EDDA and EDDA 2. Circuit elements are discrete transistors and core memories. The design is modular and extendible; modules are electrical cabinets, slide-in units, and circuit boards. The central operating clock is 50 kHz.

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Here is an overview of module use:


(Translation: "Program-Matrix" = program memory, "Entschlüsselung der Adressen und Befehle" = decoding of addresses and instructions, "Erzeugung der Grundtakte" = clock generation, "Rechenwerk mit Überwachung" = arithmetic unit with monitoring, "Netzanschluss" = power line connector, "Kernspeicher" = core memory, "Stecker zum Anschluß von Zusatzeinheiten" = connector for expansion units, "Eingabekanäle" = input channels, "Ausgabekanäle" = output channels  "Stecker zum Anschluss eines Prüfgerätes" = connector for test unit.)

Einschuebe schema



Download this file (edda3_user_manual.pdf)edda3_user_manual.pdf[EDDA3 German User's Manual ]46777 kB