KDJ11-D CPU

The KDJ11-D CPU board, formally named the KDJ11-D/S in the later variant (below), is the third QBUS CPU card using the J-11 chip set of the PDP-11 (the first two being the KDJ11-A CPU and KDJ11-B CPU. It is a quad-height board, the M7554; it is available in the so-called S-box format, for the BA200 enclosure. It was used in the PDP-11/53.

Its principal difference from the KDJ11-B is that the KDJ11-D does not support the Private Memory Interconnect bus (a high-performance variant of the QBUS); instead, it provides either .5MB or 1.5 MB (depending on the exact model) of on-board main memory (with byte parity). (Additional memory, up to the 4MB limit of the J-11, can be utilized over the QBUS.)

It also does not support the FPJ11 floating point accelerator chip (used to speed up the FP11 implementation in the J-11), and it does not have a cache. It also only supports level 4 interrupts on the QBUS (although requests at other levels are honoured; just treated as if they were level 4).

Similarly to the KDJ11B, it also provides a pair of built-in serial lines (console and printer), ROMs to contain diagnostic and bootstrap programs.

Versions

The DCJ11-D comes in two quite different main variants; unfortunately, they use the same board number, so a visual inspection is needed to know which variant a particular DCJ11-D board is.

Versions of the early variant all utilize a large number of discrete logic chips, and hold 512KB of memory. The later, 're-engineered' (as the documentation calls it) variant, has moved most of the logic into two gate arrays (DC7063 for control, and DC7064 for data paths), which made room for up to 1.5MB of memory.

The following versions of the 'early' variant exist:

• KDJ11-DA; 0.5MB, 15 MHz
• KDJ11-SA; BA200 box, 0.5MB, 15 MHz
• KDJ11-SB; BA200 box, 0.5MB, 18 MHz

The following are the versions of the 're-engineered' variant:

• KDJ11-DA (!); 0.5MB, 15 MHz
• KDJ11-DB; 1.5MB, 15 MHz
• KDJ11-SC; BA200 box, 1.5MB, 15 MHz
• KDJ11-SD; BA200 box, 1.5MB, 18 MHz

External links

• KDJ11-D/S CPU Module User's Guide (EK-KDJ1B-UG-002)