Intersil 6100

The Intersil 6100 family consists of a 12-bit microprocessor (the 6100) and a range of peripheral support and memory ICs developed by Intersil in the mid-1970s. The microprocessor implements the PDP-8 instruction set. As such it was sometimes referred to as the CMOS-PDP8. Since it was also produced by Harris Corporation, it was also known as the Harris HM-6100. The Intersil 6100 was introduced in the second quarter of 1975, and the Harris version in 1976.

The 6100 family was produced using CMOS rather than the bipolar and NMOS technologies used by most of its contemporaries (Z80, 8080, 6502, 6800, 9900, etc.). As a result of its CMOS technology and low clock speeds (8 MHz max. for the Harris HM-6100A), it had relatively low power consumption (less than 100 mW at 10 V/2 MHz) and could be operated from a single supply over the wide range of 4–11 V. Thus, it could be used in high reliability embedded systems without the need for any significant thermal management, if the rest of the system was also CMOS.

The 6100 was available to military specification and since it was dual sourced by Intersil and Harris, it was used in some military products as a low power alternative to the 8080, 6800 etc. Although it had a very simple instruction set and architecture, it was eminently suitable for use in embedded systems that had previously used discrete logic circuits and even Ledex motorised rotary switches or relay based logic controllers. In the 1980s there were still military systems in service that were using electro-mechanical relay logic controllers such as "Ledexes". When the equipment was being replaced in the 1980s, the 6100 was sometimes used; without the military equipment design constraints one of its more powerful contemporaries may have seemed more suitable.

The 6100 family was used in a number of commercial products, including the DECmate line, DEC's first attempt to produce a personal computer. Intersil sold the integrated circuits commercially through 1982 as the IM6100 family. It was not priced competitively, and the offering failed. The IBM PCs in 1981 cemented the doom of the "CMOS-8s".

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