The Intersil IM6100 - A CMOS PDP8-On-A-Chip

The Intersil IM6100 was a 12-bit microprocessor which recognised the instruction set of Digital Equipment Corporation's (DEC's) famous PDP8/e 12-bit minicomputer. The technology used was CMOS and was fully static (at a time when most competitive microprocessors used single-channel NMOS and were dynamic to keep chip size and cost down) and could be run at any clock speed up to its maximum or even halted altogether indefinitely. As a result the microprocessor was capable of very low power operation. It was used in the later DEC 'DECmate' product line and was still in use in military circles into the 1980's.

The IM6100 family included the IM6101 (Programmable Interfacing Element), IM6102 (Memory Extension/DMA Controller/Interval Timer), IM6103 (Parallel Input/Output Port), IM6512 (64 x 12 RAM), IM6312 (1024 x 12 mask-programmable ROM) and IM6402/3 (UART).

The IM6100 itself was later superceded by the IM6120, a more complete design which incorporated some of the support circuitry initially provided by other integrated circuits and in addition had a number of instructions (not a part of the 8/e set) intended to make its use as a general purpose microprocessor more convenient. The chip set was later produced by Harris under a similar set of device codes.

A minor(?) but hugely irritating oversight in the design of the family was that whilst the IM6100 was compatible with the PDP8/e, the IM6101 did not emulate the PDP-8/e's normal input/output transfer op-codes and as a result complete designs using the chip set were not software compatible with the PDP8/e. Amongst other things, this led DEC to need to rework their main operating system of the time, OS/8, for use with DECmates.

Data sheets for these integrated circuits are listed below:

Page last updated by on 29/11/2009