LSI-11 and LSI-11/2

The LSI-11 was the first microprocessor-based PDP-11 implementation, introduced in 1975. The processor was the KD11-F, a quad-height board, which had a few revisions. Although as said, it was microprocessor-based, the LSI-11 CPU consisted of several chips. The chipset is:
23-00264 Control Chip, 21-11549-00(or -01) Data Chip and two Microms: 23-002B5 and 23-001B5. The remaining socket can be used for the KEV11 option (Extended and Floating Point Instructions), which is labeled 23-003B5.

The LSI-11/2 was a dual-board version, without on-board memory. Both modules were used in PDP-11/03, PDP-11/03L and embedded systems.

KD11-F: LSI-11


Picture 1: The M7264 module

The basic KD11-F modules (M7264-AA, -AB, -BA, -BB, -CB, -DB, -EB, -FB, -HB, -JB) had 8 kB RAM on-board, the later M7264-YA, -YB and -YC versions didn't. The layout was also altered during these revisions. The CPU had a 64kByte (32kWord) addressing limit, ROMs for console ODT, but no bootstraps (which were supplied to PDP-11/03 systems via the TEV11 terminator/bootstrap modules, i.e. you also need that module to have a working system). The console can be accessed via a DLV11 SLU (Serial Line Unit) at CSR 177650 , there's no on-board serial port.

Jumpers on the module:
W1:  resident memory bank 1 selected/not selected
W2:  resident memory bank 0 selected/not selected
W3:  LTC interrupt enabled/disabled
W4:  processor-controlled memory refresh on/off
W5:  power-up mode bit 0 \
W6:  power-up mode bit 1 - if 0 and 1: ODT, if 1 and 0, PC at 173000 (user bootstrap)
W7:  -
W7:  voltage select, DO NOT CHANGE
W8:  -
W9:  enable/disable reply from local memory
W10:enable/disable reply from resident memory during refresh
W11:enable/disable on-board memory select

There was a WCS (Writeable Control Store) option of the LSI-11 called KUV11, which was another quad-height module (M8018), connected to the CPU with a ribbon cable which goes into the KEV11 option socket.

KD11-H: LSI-11/2

Picture 2: The M7270 module

This was a cost-effective version of the original LSI-11, with lower power consuption.

Jumpers on the module:
W1:  Master clock enable (DO NOT REMOVE)
W2:  -
W3:  LTC interrupt enabled
W4:  -
W5:  power-up mode bit 0  \
W6:  power-up mode bit 1  - if 0 and 1: ODT, if 1 and 0, PC at 173000 (user bootstrap)
W7:  -
W8:  -
W9:  -

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Created by: Ákos Varga Last modified: