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The KD11-A PDP-11 CPU for the PDP-11/35 and PDP-11/40 was a multi-board micro-programmed processor.

Support for the EIS was optional, with the KE11-E Extended Instruction Set, a hex card. There was also optional floating point hardware, the KE11-F Floating Instruction Set, a quad card; it was not the full FP11 Floating Point, but the minimal FIS floating point.

Memory management support was also optional, with the KT11-D Memory Management, another hex card; it too was not the full PDP-11 Memory Management, but the simplified subset. Other CPU options included the KJ11-A Stack Limit Register, and the KW11-L Line Time Clock (the latter being a standard option across a number of PDP-11 CPUs).

It used the KY11-D front panel. Provision was also made for two optional KM11-A Maintenance Sets, one for the KD11-A itself, and one for the other parts of the CPU (KE11-E, etc).


M7232 card from KD11-A

The basic KD11-A was contained on four hex cards:

  • M7231 - Data Paths
  • M7233 - IR Decode
  • M7234 - Timing
  • M7235 - Status

and one quad card:

  • M7232 - μword

The Berg connectors on the M7232 carry the microcode bus to the optional KE11-E EIS card; note also the metal edge handle on this card, even though it is only a quad card; it and the KE11-F FIS card are the only non-QBUS quad cards known to have such a handle.

All of them plugged into a wire-wrapped custom 9-slot backplane dual system unit. The optional KE11-E Extended Instruction Set, KE11-F Floating Instruction Set, and KT11-D Memory Management option cards all plugged into pre-wired slots in this backplane, as did the KJ11-A Stack Limit Register and the KW11-L Line Time Clock. This left one unused slot, which was wired as a UNIBUS SPC slot; that slot also contained the 'UNIBUS out'.

Board locations are:

Slot A B C D E F
1 M7239 FIS KM11-A (KT, KE) KM11-A (KD)
2 M7238 EIS
3 M7232 u Word KJ11-A KW11-L
4 M7231 Data Path
5 M7233 IR Decode
6 M7235 Status
7 M7234 Timing
8 M7236 KT11-D

External links