View source for KD11-EA CPU

[[Image:KD11-EA M8265.jpg|250px|right|thumb|M8265 Data Paths card]]

The '''KD11-EA CPU''' was the [[Central Processing Unit|CPU]] for the [[PDP-11/34A]] version of the [[PDP-11/34]]; it consisted of two [[DEC card form factor|hex]] [[printed circuit board]]s, the '''M8265''' Data Paths module and the '''M8266''' Control module.

The KD11-EA also supported the optional [[FP11-A Floating-Point Processor|FP11-A]] [[floating point]] ([[FP11 floating point]] type) unit and/or the [[KK11-A Cache Memory|KK11-A]] [[cache]] (it could work with either, or both).

The [[microcode]] [[address space]] was increased by one bit in the KD11-EA over the [[KD11-E CPU]], to support the extra microcode needed for the [[floating point]] [[instruction]]s.

==Implementation==

[[Image:KD11-EA M8266.jpg|250px|right|thumb|M8266 Control card]]

The implementation was much the same as [[KD11-E CPU#Implementation|that of the KD11-E]], except that the 512x4 [[Read-only memory#PROM|PROMs]] of the KD11-E were replaced by 1024x4 [[integrated circuit|chips]]:

{| class="wikitable"
! Chip !! [[DEC part number]] !! Bits !! Function
|-
| E97 || 23-022F1 || 24-27 || B, BX, OVX CTL
|-
| E98 || 23-023F1 || 28-31 || SSMUX CTL, AMUX CTL
|-
| E99 || 23-021F1 || 20-23 || FUNC CODE 01-03
|-
| E100 || 23-024F1 || 32-35 || ROM SPA 00-03
|-
| E103 || 23-011F1 || 40-43 || FORCE K, BUT SERV, PREV, FORCE RSV1
|-
| E104 || 23-025F1 || 36-39 || SPA SRC SEL0-1, SPA DST SEL0-1
|-
| E105 || 23-019A9/23-027F1 || 44-47 || BUT BITS
|-
| E106 || 23-020F1 || 16-19 || LOAD BA, LONG CYC, AUX SETUP, FUNC CODE 04
|-
| E107 || 23-019F1 || 12-15 || BUF DAT TRAN, BUF C0/C1, ENAB MAINT
|-
| E108 || 23-018F1 || 8-11 || MPC00, Misc Control
|-
| E109 || 23-017F1 || 4-7 || MPC01-04
|-
| E110 || 23-016F1 || 0-3 || MPC05-08 <!--
|-
| E52 || 23-013F1 || -->
|}

There were also minor changes (mostly chip numbering) to the Instruction Decoder PROMs:

{| class="wikitable"
! Chip !! [[DEC part number]] !! Size !! Function
|-
| E53 || 23-175A2 || 256x4 || Trap Decoder
|-
| E54 || 23-162A2 || 256x4 || Reset/Trap Decode
|-
| E59 || 23-174A2 || 256x4 || SOP Decode
|-
| E60 || 23-173A2 || 256x4 || SOP Microbranch
|-
| E61 || 23-161A2 || 256x4 || SOP ALU Control
|-
| E62 || 23-170A2 || 256x4 || Rotate/Shift ALU Control
|-
| E63 || 23-176A2 || 256x4 || Op Branch
|-
| E68 || 23-014A9 || 512x4 || Condition Codes
|-
| E69 || 23-172A2 || 256x4 || DOP Decoder
|-
| E70 || 23-349A9 || 512x4 || DOP Decoder
|-
| E72 || 23-A22A2 || 256x4 || Branch Decoder
|-
| E74 || 23-110A1 || 32x8 || [[PDP-11 Extended Instruction Set|EIS]] Decoder
|-
| E83 || 23-107A1 || 32x8 || DOP ALU Control
|}

The second 'DOP Decoder' chip is the only one which is actually different.

==FP11-A/KK11-A installation==

Adding either the FP11-A or KK11-A is fairly simple (provided there is adequate power available); they are plugged into the CPU's [[DD11-P backplane]] in the slot next to the two CPU boards, and special [[over the back|over the top]] (OTT) connectors in the form of small PCB cards bearing [[Berg connector]]s plug into Berg headers on the two neighbouring cards to connect them up.

(It is not clear why DEC adopted a design which used the OTT cards, although avoiding them would have required the more-expensive upgrade path of a new backplane; there may also not have been enough spare pins on the edge connectors.)

The KK11-A needs only an H8821 two-connector OTT card (40-pin connectors, although the ones used in the H8821 also have 2 blank pins on each end, i.e. the physical form is that of a 44-pin), which goes from the KK11-A to the M8265 card of the CPU.

The FP11-A needs both an H8821, and also the smaller 54-12416 two-connector OTT card, which goes from the M8266 card of the CPU to the FP11-A (28-pin connectors, although 2 pins on each end, and 4 in the centre, are blocked off).

If ''both'' an FP11-A ''and'' a KK11-A are plugged in, things become slightly more complex. The FP11-A '''has''' to be mounted in the slot next to the CPU boards, and the KK11-A has to be mounted in the second slot up from that one.

(The M7859 card for the [[KY11-LB Programmer's Console]] is mounted in the slot in the middle; as far as is known, there is nothing special about that slot, and the KY11-LB card could just have been moved over one slot, but DEC must have decided that the documentation would be simpler if it were always in the same slot.)

Instead of the two-connector H8821 OTT card, the very similar H8822 OTT card, with three connectors, must be used instead.

==KY11-LB Interface==

Like the [[KD11-E CPU|KD11-E]], it also supported the KY11-LB Programmer's Console, including the [[diagnostic]] functionality which allowed the CPU's microcode to be [[single-step]]ped. The KD11-EA uses the same [[KY11-L to CPU interface]] as the other machines that use them.

The interface to the KY11-LB was carried over two 10-wire [[flat cable]]s connected to [[Berg connector]] headers (denominated J1 and J2) on the M8266 module. The [[pinout]] for P1 is the same as for the KD11-E; P2 has additional signals (other than μPC08) added in the KD11-EA, though:

J2:

# Micro-PC 08
# FP11-A Attached
# Unused
# Unused
# Unused
# Micro-PC 09
# Service Br Power Fail
# Load Instruction Register
# Power Fail Br Pending
# Unused

==No-SACK Timeout Circuitry==

In the KD11-EA, the 'No-SACK timeout circuit' was moved from the optional [[M8264 No-SACK Timeout Module]] to the main CPU (on the M8265 Data Paths module). See Section 4.7.2.4, "No-SACK Timeout Circuitry", of EK-KD1EA-MM for more.
 
==See also==

* [[KD11-E/EA microcode]]
* [[KY11-LA Operator's Console]]

==External links==

* [http://www.bitsavers.org/pdf/dec/pdp11/1134/KD11EA_CPU_Maint.pdf KD11-EA central processor maintenance manual] (EK-KD1EA-MM-001)
* [http://www.bitsavers.org/pdf/dec/pdp11/1134/MP00190_1134A_KD11-EA.pdf 1134A Field Maintenance Print Set] (MP00190) - the microcode 'Flow Diagram' is mostly missing from this copy (see pg. 30 of the PDF); a complete copy of it is in the KD11-E Field Maintenance Print Set, however (they are the same; [[KD11-E/EA microcode#Microcode|errors]] there were exactly replicated in a Flow Diagram in an offline hard-copy of the KD11-EA Field Maintenance Print Set)

[[Category: PDP-11 UNIBUS Processors]]