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A KD11-D card.

The KD11-D PDP-11 CPU of the PDP-11/04 was a micro-programmed processor (making heavy use of PROMs). It was contained on single hex card (the M7263), the first PDP-11 CPU to be built on a single card.

Like other early, low-cost PDP-11s, it did not support either memory management of any kind, or hardware floating point, EIS instructions, or the various instructions added to the PDP-11 instruction set (XOR, SOB, SXT and MARK).

There is a lack of clarity over the RTT instruction; the pdp11 04/05/10/35/40/45 processor handbook says it is not implemented, but the PDP-11 Architecture Handbook says "available in 11/04 but is different from other implementations"; the KD11-D Processor Manual (EK-KD11D-TM-PRE) says the "first instruction after RTT is guaranteed to be executed" - the same as the KD11-A CPU.

It plugs into a modified MUD backplane, either the the DD11-C or DD11-D backplanes, or the special DD11-P backplane of the PDP-11/34.

It supported the KY11-LA Operator's Console and the KY11-LB Programmer's Console, including the latter's maintenance functionality which allowed the CPU's microcode to be single-stepped. The KD11-D uses the same KY11-L to CPU interface as the other machines that use them.

KY11-LB Interface

The microcode diagnostic interface to the KY11-LB is carried over a 10-wire flat cable connected to the J2 Berg connector header on the KY11-LB's M7859 module (the other 10-pin header on that card is unused with the -11/04), and a set of vertical pins in the upper left-hand corner (see image above) of the M7263. (The main functionality of the KY11-B is done over the UNIBUS, and a pair of backplane lines.)

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