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 instructions. The chip order (from the left, with the contact finger edge down, and the component side facing the viewer) is KEV11, uROM 1, uROM 0, Control, Data Path.

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); the order given in the handbook is that for the LSI-11 (no doubt an image was re-used without checking).