View source for KD11-Z CPU

The '''KD11-Z CPU''' was the [[Central Processing Unit|CPU]] of the [[PDP-11/44]]; the terminal letter code 'Z' was a tip to the fact that it was the last [[PDP-11]] CPU to be made out of discrete [[integrated circuit|chips]], and not a [[microprocessor]], and also nearly the last native [[UNIBUS]] CPU (except for the [[KDF11-U CPU|KDF11-U]]).

The KD11-Z used the [[Extended UNIBUS]] for its [[bus]] to [[main memory]], allowing it to have up to 4 mega-[[byte]]s of main memory. All devices were attached to a semi-separate [[UNIBUS]] (it and the EUB shared data lines, but not address lines); [[Direct Memory Access|DMA]] devices could gain access to the memory via a [[UNIBUS map]] which connected the two, and mapped UNIBUS addresses to main memory addresses.

Full [[PDP-11 Memory Management]] and a [[cache]] (the [[KK11-B Cache Memory|KK11-B]]) were standard on all KD11-Z's. It also supported the optional [[FP11-F Floating-Point Processor|FP11-F]] [[floating point]] (full [[FP11 floating point]]) and/or the [[KE44-A Commercial Instruction Set Processor]]; these plugged into dedicated slots in the CPU [[backplane]] (it could work with either, or both).

==Hardware Details==

The basic KD11-Z CPU consisted of five [[DEC card form factor|hex]] boards:

* M7094 Data Path module
* M7095 Control module
* M7096 Multifunction module
* M7097 KK11-B Cache module
* M7098 UNIBUS interface module

In addition, a single dual board, the M7090 Console Interface module, held a number of [[Berg connector]] headers used for various [[input/output]] functions.

These were placed in a 14-slot CPU-specific [[backplane]] ([[DEC part number]] 70-16502 for the complete assembly, 54-13593/50-13592 for the [[printed circuit board|PCB]]), along with the optional FP11-F and KE44-A, and all the main memory cards (M8722 [[MS11-M MOS memory|MS11-M]], or later the M8743 [[MS11-P MOS memory|MS11-P]]); the EUB was only present on the main backplane. That left two slots, one [[Modified UNIBUS Device|MUD/SPC]] slot, and one [[Small Peripheral Controller|SPC]] slot, which also contained the 'UNIBUS out'.

Board locations are:
<!-- (as seen from the board insertion side of the backplane, not the wire-wrap pin side, as is common in [[Digital Equipment Corporation|DEC]] documentation) -->

{| class="wikitable"
! !! colspan="6" | Connector
|-
! Slot !! A !! B !! C !! D !! E !! F
|-
| 1 || colspan="2" style="text-align:center;" | M7090 CIM || colspan="4" style="text-align:center;" | M7091 CIS
|-
| 2 || colspan="6" style="text-align:center;" | M7092 CIS
|-
| 3 || colspan="6" style="text-align:center;" | M7093 Floating point
|-
| 4 || colspan="6" style="text-align:center;" | M7094 Data paths
|-
| 5 || colspan="6" style="text-align:center;" | M7095 Control
|-
| 6 || colspan="6" style="text-align:center;" | M7096 MFM
|-
| 7 || colspan="6" style="text-align:center;" | M7097 Cache
|-
| 8 || colspan="6" style="text-align:center;" | M7098 UNIBUS interface
|-
| 9 || colspan="6" style="text-align:center;" | main memory
|-
| 10 || colspan="6" style="text-align:center;" | main memory (optional)
|-
| 11 || colspan="6" style="text-align:center;" | main memory (optional)
|-
| 12 || colspan="6" style="text-align:center;" | main memory (optional)
|-
| 13 || colspan="6" style="text-align:center;" | MUD/SPC
|-
| 14 || colspan="2" style="text-align:center;" | UNIBUS Out || colspan="4" style="text-align:center;" | SPC
|}

[[Image:1144Power.jpg|300px|thumb|right|PDP-11/44 power cabling setup]]

The details of how the EUB and UNIBUS interoperated are not yet clear (it is not covered in [[Digital Equipment Corporation|DEC]]'s documentation); it was almost certainly similar to that used in the [[PDP-11/24#Implementation details|-11/24]].

The standard [[mounting box]] for the CPU was the [[BA11-A mounting box|BA11-A]], which is unusual in that it does not use only the standard [[DEC power distribution connectors]]; it provided special connections on a[[bus bar]]s in its power supply, and the KD11-Z backplane uses unique [[Flexprint cable]]s for power, which go to the special connections (see image).

==External links==

* [http://bitsavers.org/pdf/dec/pdp11/1144/MP00897_11X44sys_Dec79.pdf 11X44 Field Maintenance Print Set] - the KD11-Z Field Maintenance Print Set (MP00812) is on pp. 10-105
* [http://bitsavers.org/pdf/dec/pdp11/1144/1144_SystemTechMan.pdf PDP-11/44 System Technical Manual] - the KD11-Z is covered in Chapters 2 and 6

[[Category: PDP-11 UNIBUS Processors]]
[[Category: Extended UNIBUS]]