150 (NORD-1 card)

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150 Register, is a card that is used as the instruction register in the NORD-1 CPU. It holds the current instruction during execution.

Component side.
Solder side.


The card is made in the standard NORD-1 card format.

CPU model Crate position
29 C09
35 C09

The logic diagram is documented in drawing 2A50.[1]

The content of the IR is set by the MJ-bus and strobed by the IS1-0 signal on pin 29 and 30. The IS2-0 strobe forces the IR to 161402 (IOT SKA #2) or 161422 (IOT SKA #22) depending on the state of LEN-1, this is a load sequence initiated from the operators panel.

IS2-0 strobe comes from the 122 Assembler card, where the IS1-0 signal comes from isn't known yet.

Switches and indicators

There are no switches or indicators on this board.


This list contains the logic circuits used, passive components are not listed.

  • 4 x 7400
  • 4 x 7440
  • 8 x 7474