KD11-A CPU
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).
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).
Implementation
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:
| Connector | ||||||
|---|---|---|---|---|---|---|
| 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 | |||||
| 9 | UNIBUS Out | SPC | ||||
External links
- KD11-A processor manual (DEC-11-HKDAA-A-D)
- KD11-A processor maintenance manual (EK-KD11A-MM-001)
- PDP-11/40 system engineering drawings (pp. 9-108 of the PDF)
- What Makes A PDP-11/35 Tick? - List of chips in the KD11-A
