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Intel 4004
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The Intel 4004 is a 4-bit central processing unit (CPU) released by Intel Corporation in 1971. The 4004 is the first complete CPU on one chip, the first commercially available microprocessor, a feat made possible by the use of the new silicon gate technology allowing the integration of a higher number of transistors and a faster speed than was possible before. The 4004 employed a 10 µm silicon-gate enhancement load pMOS technology and could execute approximately 92,000 instructions per second (that is, a single instruction cycle was 11 microseconds).
4004 was released on November 15, 1971.
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The Intel 4004 is a 4-bit central processing unit (CPU) released by Intel Corporation in 1971. The 4004 is the first complete CPU on one chip, the first commercially available microprocessor, a feat made possible by the use of the new silicon gate technology allowing the integration of a higher number of transistors and a faster speed than was possible before. The 4004 employed a 10 µm silicon-gate enhancement load pMOS technology and could execute approximately 92,000 instructions per second (that is, a single instruction cycle was 11 microseconds).
History and description
The 4004 was released on November 15, 1971. Packaged in a 16-pin ceramic dual in-line package, the 4004 is the first computer processor designed and manufactured by chip maker Intel, which previously made semiconductor memory chips. The chief designers of the chip were Federico Faggin and Ted Hoff of Intel, and Masatoshi Shima of Busicom (later of ZiLOG, founded by Federico Faggin).
Federico Faggin was the only chip designer among the engineers participating to the MCS-4 project. He was also the only one with experience in MOS random logic and circuit design and with the crucial intimate knowledge of the new silicon gate process technology he had created at Fairchild in 1968. As soon as he joined the Intel MOS Department he created a new random design methodology based on silicon gate, and contributed many technology and circuit design inventions that enabled a single chip microprocessor to become a reality for the first time. His methodology set the design style for all the early Intel microprocessors and later for the Zilog’s Z80. He also led the MCS-4 project and was responsible for its successful outcome (1970-1971). Ted Hoff, head of the Application Research Department, contributed only the architectural proposal for Busicom working with Stan Mazor in 1969, then he moved on to other projects. Shima designed the Busicom calculator firmware and assisted Faggin during the first six months of the implementation. The manager of Intel's MOS Design Department was Leslie L. Vadász. At the time of the MCS-4 development Vadasz's attention was completely focused on the mainstream business of semiconductor memories and he left the leadership and the management of the MCS-4 project to Faggin.
Originally designed for the Japanese company Busicom to be used in their line of calculators (instead of the complex special purpose calculator chipset that Busicom had designed themselves and brought to Intel to have made, which Intel determined was too complex to make with the technology they had at the time), the 4004 was also provided with a family of custom support chips. For instance, each "Program ROM" internally latched for its own use the 4004's 12-bit program address, which allowed 4 KB memory access from the 4-bit address bus if all 16 ROMs were installed. The 4004 circuit was built of 2,300 transistors, and was followed the next year by the first ever 8-bit microprocessor, the 3,300 transistor 8008 (and the 4040, a revised 4004).
A popular myth has it that Pioneer 10, the first spacecraft to leave the solar system, used an Intel 4004 microprocessor. However, according to Dr. Larry Lasher of Ames Research Center, the Pioneer team did evaluate the 4004, but accordingly it was too new at the time to include in any of the Pioneer projects. The myth was repeated by Federico Faggin himself in a lecture for the Computer History Museum in 2006.
On 15 November 2006, the 35th anniversary of the Intel 4004, Intel celebrated by releasing the chip's schematics, mask works, and user manual.
The 4004 and the MCS-4 family
The 4004 is a complete CPU (central processing unit) integrated in a single chip, making the 4004 the world's first microprocessor. Before the microprocessor, CPUs were built with many chips or with a few LSI (large scale integration) chips. The CPUs built with a few LSI chips were steps toward the microprocessor but were not microprocessors.
The 4004 is part of a family of four LSI components - the MCS-4 family - that can be used to build digital computers with varying amounts of memory. The other components of the MCS-4 family are memories and input/output circuits, which are not considered part of a CPU in any computer classification, but are necessary to implement a complete computer. Specifically:
- the 4001 is a ROM (read-only memory) with 4 lines of I/O (input/output)
- the 4002 is a RAM (random access memory) with 4 lines of output
- the 4003 is a static shift register to be used for expanding the I/O lines, for example, for keyboard scanning or for controlling a printer
The functional elements integrated in the 4004 are:
- 16 general purpose registers
- program counter and three levels of return address stack
- ALU both binary and decimal
- instruction decoder and all the control logic for the internal functional blocks of the CPU
- generation of timing signal for the CPU and for the rest of the MCS-4 family
- control of the external bus for the memory and for the I/O functions.
The 4004 included also the control functions for the memory and the I/O which are not normally handled by the microprocessor. The 4004, therefore, is not only a complete CPU, but has also additional functionality that normally is not considered a part of a CPU (microcontroller).
The first commercial product to use a microprocessor was the Busicom calculator 141-PF.
First microprocessor commercially available and sold as a component set
According to Nick Tredennick, a recognized engineer and microprocessor designer, and an expert witness to the Boone/Hyatt patent case:
Technical specifications
- Maximum clock speed is 740 kHz
- Separate program and data storage (i.e., a Harvard architecture). Contrary to most Harvard architecture designs, however, which use separate buses, the 4004, with its need to keep pin count down, uses a single multiplexed 4-bit bus for transferring:
- 12-bit addresses
- 8-bit instructions
- 4-bit data words
- Instruction set contains 46 instructions (of which 41 are 8 bits wide and 5 are 16 bits wide)
- Register set contains 16 registers of 4 bits each
- Internal subroutine stack is 3 levels deep.
Microarchitecture and pinout
Click the pictures to view the full-size versions.
Support chips
- 4001: 256-byte ROM (256 8-bit program instructions), and one built-in 4-bit I/O port
- 4002: 40-byte RAM (80 4-bit data words), and one built-in 4-bit output port; the RAM portion of the chip is organized into four "registers" of twenty 4-bit words:
- 16 data words (used for mantissa digits in the original calculator design)
- 4 status words (used for exponent digits and signs in the original calculator design)
- 4003: 10-bit parallel output shift register for scanning keyboards, displays, printers, etc.
- 4008: 8-bit address latch for access to standard memory chips, and one built-in 4-bit chip select and I/O port
- 4009: program and I/O access converter to standard memory and I/O chips
- 4269: keyboard/display interface
- 4289: memory interface (combines functions of 4008 and 4009)
Naming the first microprocessor
When Federico Faggin designed the MCS-4 family he also christened the chips with distinct names: 4001, 4002, 4003, and 4004, breaking away from the numbering scheme used by Intel at that time which would have required the names 1302, 1105, 1507, and 1202 respectively. Had he followed Intel's number sequence, the idea that the chips were part of a family of components intended to work seamlessly together would have been lost.
Intel's early numbering scheme for integrated circuits contemplated using a four-digit number for each component. The most significant digit position indicated the process technology used, as follows: The number "1" meant P-channel MOS, "2" indicated N-channel MOS, "3" was reserved for bipolar technology, and "5" was used for CMOS technology. No other numbers were used.
The next most significant digit was used to indicate the generic function performed by the component, as follows: "1" was used for RAM, "2" indicated random logic, "3" indicated ROM, "5" meant shift register, "6" and "7" were used for one-time programmable ROM and EPROM respectively. The last two digits of the number were used to indicate the sequential number in the development of the component.
Collectible value
The Intel 4004 is one of the world's most sought-after collectible/antique chips. Of highest value are 4004s that are gold and white, with so-called 'grey traces' visible on the white ceramic (the original package type). As of 2005, such chips have reached around US$1000 each on eBay. The slightly less valuable white and gold chips without grey traces typically reach $300 to $500. Those chips without a 'date code' underneath are earlier versions, and therefore worth slightly more. More recently however, these vintage ICs have been dropping in value due to their relative abundance as the market is now flooded with surplus stock from sellers looking to cash in on the Intel craze.
Original publications
- F. Faggin and M.E. Hoff: "Standard parts and custom design merge in four-chip processor kit". Electronics/April 24, 1972, pp. 112-116
- F. Faggin, M.Shima, M.E. Hoff, Jr., H. Feeney, S. Mazor: "The MCS-4 An LSI micro computer system". IEEE '72 Region Six Conference
Patents
- US Patent 3,753,011 August 14, 1973. Faggin, Federico: Power supply settable bi-stable circuit.
- US Patent 3,821,715 June 28, 1974. Hoff, Marcian; Mazor, Stanley; Faggin, Federico: Memory system for multi-chip digital computer.
External links
- — Intel Museum (Intel Corporate Archives) entry.
- — Faggin's own 4004 website.
- — at the IEEE's History Center.
- — Intel Corp., November 1971; at the Smithsonian's Chip Collection.
- — at Christian Bassow's CPU Museum.
- — at the unofficial 4004 website, and a simulator in Java.
- ."The silicon design is the essence of the first microprocessor" - Federico Faggin. At the time of the microprocessor's invention engineers knew how to define CPU's architectures and do logic designs but did not yet know how to design a single-chip microprocessor in silicon.
- : The Silicon Gate Technology was first presented by its developer, Federico Faggin, at the IEDM on October 23, 1968 in Washington, D.C.
- : Features the Fairchild 3708, the world's first commercial integrated circuit using Silicon Gate Technology, developed by Federico Faggin at Fairchild in 1968.
- Simple programming tools for Intel 4004 in Javascript.
Intel datasheets:
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