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MCS-4 - Intel
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Intel MCS-4
The entire MCS-4 chipset: 4001, 4002, 4003, and 4004.
Developer Intel
Manufacturer Intel
Type Microprocessors
Production 1971-1982
Release date November 15, 1971
Architecture 4-bit word, 8-bit instruction, BCD-oriented
Word size 4 bit
0.5 octets
1 nibbles
Process 10 μm
10,000 nm
0.01 mm
Technology pMOS
Clock 500 kHz-740 kHz
Package DIP16

The MCS-4 (Micro-Computer Set-4) or 4000 Series or Busicom Chip Set was a family of 4-bit microprocessor chipsets developed by Intel. The entire chipset was made of four individual chips, including the 4004 CPU which became the first commercial microprocessor. MCS-4 was completed by March 1971, entered production in June, and introduced into the market on November 15, 1971.


An ad for the MCS-4 in the Nov. 15, 1971 issue of Electronic News

Before Federico Faggin joined Intel in 1970, the development of the 4004 was rather slow. Federico developed several design innovations at Intel that made it possible to fit the microprocessor in one chip, including new methodology for random logic chip design using silicon gate technology[1]. Faggin developed the 4004 testing tool, chip and logic design concurrently with the layout of all the chips of the entire MCS-4 system.

At the time, Intel was only known for their memory chips. On 15 November 1971, they publicly announced the first commercial microprocessor in the 15th issue of Electronic News. The prophetic ad read: "Announcing a new era in integrated electronics". The chip was designed by Federico Faggin, Ted Hoff and Masatoshi Shima; it received U.S. Patent #3,821,715.

All the MCS-4 components were packaged in 16-pin ceramic DIP. The 16-pin package, which proved to be the most problematic restriction was imposed by management.


The MCS-4 can be minimally functioning with just the 4001 ROM and the 4004 CPU, however its designed to be fully functioning with RAM and shift register. Additionally two more chips, the 4008 and 4009, expand the system to work with any of Intel's existing memory chip selections.

Part Description
4001 ROM
4002 RAM
4003 shift register
4004 MPU
4008 Address latch
4009 I/O Interface


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intel mcs-4.svg

Lead Designers[edit]

Lead designers for the MCS-4 family were:

  • Ted Hoff
  • Federico Faggin
  • Stan Mazor
  • Masatoshi Shima



  1. Faggin. Il padre del chip intelligente, Angelo Gallippi, 2002, 88-7118-149-2

See Also[edit]

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Facts about "MCS-4 - Intel"
designerIntel +, Ted Hoff +, Federico Faggin +, Stan Mazor + and Masatoshi Shima +
full page nameintel/mcs-4 +
instance ofmicroprocessor family +
main designerIntel +
manufacturerIntel +
nameIntel MCS-4 +
packageDIP16 +
process10,000 nm (10 μm, 0.01 mm) +
technologypMOS +
word size4 bit (0.5 octets, 1 nibbles) +