Various peripherals could be connected to EDDA 3 in a flexible way.

As input, devices like keyboard, scales, and switches were used.

As output, thyristors as circuit breakers actuated valves or motors, or 4-digit Nixie displays were used.

All together, EDDA 3 can be extended to 1400 input and output channels! They are arranged hierarchical:

  • The main distributor EDEA1 is connected to the EDDA 3 computer.
    The distributor EDEA1 has up to 7 cabinet distributors EDEA2.
  • A cabinet distributor EDEA2 has up to 10 channel plug-in boards EDEA3.
  • A channel plug-in board EDEA3 has a unique address in an EDDA system (00 to 99) and contains channels in form of circuit boards at data addresses 70 to 89.

Each channel expansion card EDEA3 allocates the same addresses 70 to 89 in the data address space. However, at any give time only one of these boards is selected to be accessible in this data address window.  The number of this channel plug-in board is written to data address 65.


EA-System schema

(Translation: "Rechner" = computer, "Hauptverteiler" = main distributor, "Schrankverteiler" = cabinet switch, "Kanaleinschub" = plug-in board, "Kanal" = channel, "Eingabeeinheit" = input unit).

The following additional input and output channels existed:

ESEA11: contact input (switch monitoring)

ESEA12: number input 1-of-10

ESEA13: number input BCD 4-digit

ESEA14: contact output flipflop for 4 REED contacts

ESEA15: Parallel digit display, 2-of-5 code

ESEA32: contact output monoflop for 4 REED contacts (pulse output)

EDEA5: extra cabinet for input of larger amounts of digital data, 400 mechanical contacts with "only" 47 circuit boards