# DEC Microprocessors

## Introduction

DEC began working in semiconductor technology in the early 1970's, when it collaborated with Western Digital on one of the first 16b microprocessors, the LSI-11. From that modest start, semiconductor-related projects grew to encompass chip design, CAD tool engineering, process technology, and silicon manufacturing and test. In 1979, all of the groups working in semiconductors moved to a new, state-of-the-art facility in Hudson, Massachusetts. In 1981, the groups were unified into a single organizational structure, first known as the VLSI Group, then the Semiconductor Group, and finally as Digital Semiconductor. The group operated as an integrated engineering/manufacturing business until 1996, when the manufacturing and non-microprocessor design teams were sold to Intel. In 2000, all the microprocessor design teams were sold to Intel, bringing the three-decade history of Digital Semiconductor to an end.

I joined the semiconductor design group (then known as CSD/LSI, I believe) in 1978, as a strategic analyst. Over the next twelve years, I worked as project manager of the J-11 (1979-1981), group manager of Advanced Development (1981-1984) and project manager of MicroVAX II (1982-1984), group manager of Microprocessor Development (1984-1988), Technical Director (1988-1990), and Alpha Program Manager (1988-1992). I left in 1990, when the Alpha Program was transferred from the Semiconductor Group to the VMS Systems Group. These twelve years were the happiest and most productive of my career at DEC. I worked with some of the best engineers in the business. I had the opportunity to shape, manage, and contribute to the highly successful VAX microprocessor series: MicroVAX II, CVAX, Rigel, and NVAX.

## Microprocessors Through 1992

Each micprocessor design project is described in greater detail on its own page. Links to chip photographs are provided on the detail pages.

- PDP-11:
  - LSI-11
  - F-11
  - T-11
  - J-11
- VAX:
  - V-11
  - MicroVAX II
  - CVAX
  - Rigel
  - Mariah
  - NVAX
- RISC:
  - MicroPrism
  - EV-4
- Other:
  - MPP
  - Raven

## Specifications, Microcode, and Memoranda

Selected microcode listings, specifications, and memoranda from the heyday of Digital Semiconductor.

- J-11: microcode listing
- MicroVAX:
  - Design specification
  - Microcode documentation
  - Microcode sources
- CVAX:
  - Chip specification
  - Design specification
  - Microcode documentation
  - Microcode sources
- Rigel and Mariah:
  - Instruction timing
  - Microcode sources
- NVAX:
  - Instruction timing
  - Microcode listing
- Raven: microcode sources
- Cross-generational:
  - Instruction sets
  - Microcode size budgets
  - Bugs and causal analysis
  - Microcode tools

Updated 24-Feb-2008 by Bob Supnik (simh AT trailing-edge DOT com - anti-spam encoded)