LSI-11

The LSI-11 was DEC's first cost-reduced PDP-11 processor, using the QBUS. Several different LSI-11 models exist, including the KDF11-F (quad form factor), and the KD11-HA (dual form factor), also called the LSI-11/2.

However, they all use the same chip set internally, the Western Digital WD16/CP1600 (alternative designations). The chip set consists of a data path chip, a control chip, and two or three microcode ROMs (each holding 512 words which are 22 bits wide). The third uROM is optional, and is the KEV11, for the EIS/FIS instructions.

LSI-11

The LSI-11 is a quad board (M7264) with additional functionality on-board (making possible a single-board computer): the base KD11-F version includes 4KW of MOS RAM; the KD11-H version has the RAM deleted; the KD11-Q includes a uROM for DIBOL.

LSI-11/2

The LSI-11 is a dual board (M7270).

Note that the image in the "Microcomputer Products Handbook" (pg. C-18) is erroneous; the order of the chips (from the handle end) is, in fact, KEV11, Control, uROM 1, uROM 0, Data Path (per the KD11-HA print set).