KA11 changes for the KT11-B

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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:

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:

Pin Source Signal
A1  ? Ground
A2  ? xx
B1  ? xx
B2  ? xx
C1  ? Ground
C2  ? Ground
D1  ? xx
D2  ? xx
E1  ? xx
E2  ? xx
F1  ? Ground
F2  ? Ground
H1  ? xx
H2  ? xx
J1  ? xx
J2  ? Ground
K1  ? Ground
K2  ? xx
L1  ? xx
L2  ? Ground
M1  ? xx
M2  ? xx
N1  ? Ground
N2  ? Ground
P1  ? xx
P2  ? xx
R1  ? Ground
R2  ? Ground
S1  ? xx
S2  ? xx
T1  ? Ground
T2  ? xx
U1  ? xx
U2  ? Ground
V1  ? xx
V2  ? xx