View source for KA11 changes for the KT11-B

The [[KT11-B Paging Option]] for the [[PDP-11/20]] involves some modifications to the [[KA11 CPU]]. Those changes are documented in a [[DEC]] print set, 7605961-0, "Central Processor for KT11-B".

Alas, there's only one known set of these prints for the KT11-B changes to the KA11 - and that set is missing a page: "PC Board Modifications", D-AP-7605961-0-10.

Luckily, there is probably just duplicate information elsewhere (including a hand-modified set of KA11 prints, showing the changes to suppport the KT11-B) to allow it to be reproduced.

==Print set==

The following prints are included in the "Central Processor for KT11-B" set:

{| class="wikitable"
! Drawing !! Sheets !! Title
|-
| D-CS-7605961-0-3 || 3 || State Control - M727 K2
|-
| D-CS-7605961-0-4 || 3 || Priority - M824 K3
|-
| D-CS-7605961-0-5 || 5 || Bus Interface & Instruction Register - M725 K9
|-
| D-CS-7605961-0-6 || 4 || Instruction Register Decode - M726 K10
|-
| D-CS-7605961-0-7 || 3 || Flag Control - M822 K12
|-
| D-CS-7605961-0-8 || 4 || Bus & Console Control - M724 K13
|}

==KA/KT Interface==

The KA11 and KT11-B are connected by a single cable which carries specific signals, as well as the [[UNIBUS]]. On the KT11 end, it plugs into slot D12, and on the KA11 end, into slot B09. The cable pinout is:

{| class="wikitable"
! Pin !! Source !! Signal !! ! Pin !! Source !! Signal
|-
| A1 || - || Ground || A2 || ? || xx
|-
| B1 || KA11 || Odd address error || B2 || ? || xx
|-
| C1 || - || Ground || C2 || - || Ground
|-
| D1 || KT11 || PGC 04 || D2 || KA11 || RTS
|-
| E1 || KA11 || DEST || E2 || KA11 || CLKT
|-
| F1 || - || Ground || F2 || - || Ground
|-
| H1 || KA11 || SOURCE || H2 || KA11 || -TRAPS
|-
| J1 || KA11 || ISR 12 || J2 || - || Ground
|-
| K1 || - || Ground || K2 || KA11 || SERVICE
|-
| L1 || KA11 || ISR 7 || L2 || - || Ground
|-
| M1 || KA11 || -RTI || M2 || KA11 || TIME OUT
|-
| N1 || - || Ground || N2 || - || Ground
|-
| P1 || KA11 || JSR || P2 || KA11 || FETCH
|-
| R1 || - || Ground || R2 || - || Ground
|-
| S1 || KT11 || CLK NPR || S2 || KA11 || TRAP
|-
| T1 || - || Ground || T2 || KA11 || [ST+SR] K13-3
|-
| U1 || ? || xx || U2 || - || Ground
|-
| V1 || ? || xx || V2 || KT11 || Force timeout
|}

(Signals partially in lower case are not formal names from the prints, but give a sense of what the signal does.)

==KA11 modifications==

An M138 FLIP CHIP (octal three-input NAND gates) is also plugged into the KA11 backplane (in slot B08, otherwise unused), to provide additional gates.

===Wires removed===

The following lists of wiring changes on the KA11 backplane give the content from print 7605961-0-11, "KA11 Mods For Use With KT11-B". All wires are listed as being 30 AWG.

'''Note:''' This print reproduced poorly, so there may be transcription errors (e.g. '8' for '3', etc). '?' indicates an un-readable character. Text in ''italics'' are comments added during transcription to this page.

{| class="wikitable"
! From !! To !! Signal !! Colour
|-
| B02T2 || F08U2 || K13-3 B MSYN H || rowspan="6" style="text-align:center;" | Orange
|-
| D12C2 || D12S1 || GND 12
|-
| E04K1 || E07P2 || K10-4 CLKT H
|-
| E03F1 || E04L1 || K?-2 SCLK L
|-
| D11B1 || C06J1 || K10-3 ODD ADRS ERR L
|-
| C06J1 || D02N1 || K10-3 ODD ADRS ERR L
|-
| D12S1 || D12T1 || GND 12 || Brown
|}

===Wires added===

All added wires are listed as Orange. This list had previously been checked, and annotated by hand in ink; those annotations are given here. All entries with no annotation given have a hand-written check-mark in ink.

{| class="wikitable"
! From !! To !! Signal !! Comment
|-
| E03F1 || F06H1 || K1-2 SCLK L ||
|-
| D?2C2 || D12T1 || GND 12 || None
|-
| D11B1 || D02N1 || K10-3 ODD ADDRS ERR L || None
|-
| F04P2 || B08A1 || K10-2 ODD ADDRS ERR L  || rowspan="5" style="text-align:center;" |
|-
| F04P2 || B08B1 || K10-2 ODD ADDRS ERR L 
|-
| F04P2 || B08C1 || K10-2 ODD ADDRS ERR L 
|-
| B08D1 || B08E1 || B08D1
|-
| B08D1 || B08L1 || B08D1
|-
| E03F1 || B08M1 || K1-2 SCLK L || E04L1 - B08M1
|-
| B08J1 || B08K1 || B08J1 || rowspan="12" style="text-align:center;" |
|-
| B08J1 || C06J1 || B08J1
|-
| B08N1 || B09B1 || B08N1
|-
| E04K1 || B08P1 || K10-2 CLKT H
|-
| E04K1 || B08R1 || K10-2 CLKT H
|-
| E04K1 || B08S1 || K10-2 CLKT H
|-
| B08U1 || B08D2 || B08U1
|-
| B08U1 || B08F2 || B08U1
|-
| B09D1 || B08F1 || D18 - PGC 04 (1) H
|-
| B09D1 || B08H1 || D18 - PGC 04 (1) H
|-
| B09D1 || B08F2 || D18 - PGC 04 (1) H
|-
| B08H2 || B08J2 || B08H2
|-
| B08H2 || B0K2 || B08H2 || (''Presumably 'B0K2' is a typo for 'B08K2''')
|-
| B08H2 || B08L2 || B08H2 || rowspan="3" style="text-align:center;" |
|-
| B08H2 || E07P2 || B08H2
|-
| D03T2 || B08R2 || K1-4 SERVICE H
|-
| E03L2 || B08N2 || K1-3 ISR (3+7) H || None
|-
| B08S2 || B08T2 || B08S2 || rowspan="3" style="text-align:center;" |
|-
| B08S2 || B08U2 || B08S2
|-
| B08S2 || B08V2 || B08S2
|-
| D11B2 || B08P2 || K12-3 TRAPS || B02C1 - B08P2
|-
| F03J1 || B09E1 || K1-3 B DEST (0) H ||
|-
| F03M2 || B09M2 || K1-4 B SOURCE (1) H || B09H1 - F11M2
|-
| E03R1 || B09J1 || K1-3 ISR 12 L || rowspan="5" style="text-align:center;" |
|-
| E03K1 || B09L1 || K1-3 ISR 7 L
|-
| F04S2 || B09M1 || K10-4 RTI H
|-
| C04D1 || B09P1 || K10-2 JSR H
|-
| B09S1 || F02U2 || D18 CLK NPR H
|-
| E04R1 || B09D2 || K10-3 RTS || B09D2 - E11T2
|-
| D03P2 || B09K2 || K1-4 SERVICE L || rowspan="4" style="text-align:center;" |
|-
| F06M1 || B09M2 || K13-3 TIME OUT (0) H
|-
| F03J2 || B09P2 || K1-4 FETCH (0) H
|-
| C04P1 || B09S2 || K10-2 TRAP L
|-
| C06V1 || B09T2 || K13-3 -(ST+SR) H || D06D2 - B11T2
|-
| B09V2 || F06C1 || D18 FORCE TIMEOUT H || rowspan="2" style="text-align:center;" |
|-
| B08V1 || B09H2 || B08V1
|-
| F02J1 || D06D2 || K2-3 CLR PTR L || None
|-
| F02P1 || D12S1 || K2-3 PERIF REL L || None
|-
| B12P2 || B12V2 || DEVICE 2+3 BG06 || rowspan="3" style="text-align:center;" |
|-
| D11H2 || E04L1 || K1-2 R/W2 H
|-
| B08M2 || B09E2 || B08M2
|-
| F02J1 || C06V1 || - || rowspan="2" style="text-align:center;" | Unlisted (''Not in original table; added by hand'')
|-
| B09H1 || F11M2 || -
|}