KD11-E CPU

M7265 Data Paths card

The KD11-E CPU was the first CPU version for the PDP-11/34; it consisted of two hex printed circuit boards, the M7265 Data Paths module and the M7266 Control module. They plugged into a modified MUD backplane, the DD11-P backplane, which was customized for the KD11-E.

Although it supported the KY11-LB Programmer's Console, including the diagnostic functionality which allow the CPU's microcode to be single-stepped, it did not support the FP11-A floating point unit or the KK11-A cache; a PDP-11/34 system needed the upgraded KD11-EA CPU for that.

The KD11-E uses the same KY11-L to CPU interface as the other machines that use them.

M7266 Control card

Implementation

The KD11-E makes heavy use of PROMs, to hold the microcode, to control the ALU, provide trap addresses, and for instruction decoding. The latter is partially accomplished in microcode, but with extensive assistance from an Instruction Decoder largely implemented in PROMs. The latter has several functional sub-units:

• DOP Decoder, double-operand instructions
• SOP Decoder, single-operand instructions
• Branch Decoder, branch instructions
• Operate Decoder, condition codes instructions

The Instruction Decoder also checks for illegal instructions, and illegal addressing modes on otherwise-legal instructions.

The microcode is 48 bits wide, stored in 12 512x4 PROMs:

Chip	DEC part number	Bits	Function
E97/E94	23-021A9	24-27	B, BX, OVX CTL
E98/E95	23-022A9	28-31	SSMUX CTL, AMUX CTL
E99/E96	23-020A9	20-23	FUNC CODE 01-03
E100/E97	23-023A9	32-35	BUT BITS
E102/E111	23-025A9	40-43	FORCE K, BUT SERV, PREV, FORCE RSV1
E103/E112	23-024A9	36-9	SPA SRC SEL0-1, SPA DST SEL0-1
E104/E113	23-026A9	44-47	ROM SPA 00-03
E105/E114	23-019A9	16-19	LOAD BA, LONG CYC, AUX SETUP, FUNC CODE 04
E106/E115	23-018A9	12-15	BUF DAT TRAN, BUF C0/C1, ENAB MAINT
E107/E116	23-017A9	8-11	MPC00, Misc Control
E108/E117	23-016A9	4-7	MPC01-04
E109/E118	23-015A9	0-3	MPC05-08

Note: The chip numbers in the KD11-E FMPS (MP0004) are given with two differing assignments; the 'Control Word' diagram (pg. 1 of the 'KD11-E Flow Diagrams') gives one set of numbers (the second, in the table above); the actual prints of the M7266 use another (given as the first in the table above).

Instruction Decoder uses 13 PROMs, of differing sizes:

Chip	DEC part number	Size	Function
E52	23-175A2	256x4	Trap Decoder
E53	23-162A2	256x4	Reset/Trap Decode
E58	23-174A2	256x4	SOP Decode
E59	23-173A2	256x4	SOP Microbranch
E60	23-161A2	256x4	SOP ALU Control
E61	23-170A2	256x4	Rotate/Shift ALU Control
E62	23-176A2	256x4	Op Branch
E67	23-014A9	512x4	Condition Codes
E68	23-172A2	256x4	DOP Decoder
E69	23-171A2	256x4	DOP Decoder
E71	23-A22A2	256x4	Branch Decoder
E73	23-110A1	32x8	EIS Decoder
E81	23-107A1	32x8	DOP ALU Control

KY11-LB Interface

The microcode diagnostic interface to the KY11-LB is carried over two 10-wire flat cables with female Berg connectors connected to wire-wrap pin groups (denominated J1 and J2) in the upper left corner of the M7266 module. (The main functionality of the KY11-B is done over the UNIBUS, and a pair of backplane lines.)

See also

• KD11-E/EA microcode

External links

• KD11-E central processor maintenance manual (EK-KD11E-TM-001)
• 11/34 Vol. 2 Field Maintenance Print Set (MP00082) - KD11-E is covered on pp. 41-62