Intel 4004 Definition

The Intel 4004 was the world's first single-chip microprocessor. Released by Intel Corporation on November 15, 1971, it became a much greater success than could have ever been imagined, including leading to a major technology revolution.

A microprocessor, also referred to as a processor and a central processing unit (CPU), is a semiconductor device that contains the basic arithmetic, logic and control circuitry that are at the core of a computer's operation.

A single chip microprocessor is a microprocessor all of whose circuitry is contained on a single tiny piece of silicon (i.e., a chip). Originally, microprocessors were composed of a large number of discrete circuit elements (mainly transistors, resistors, diodes and capacitors). At the time of the introduction of the 4004, other microprocessors were available as chip sets, that is, sets of several integrated circuit (IC) chips, all of which could be mounted on a single printed circuit board to construct a complete microprocessor.

The eventual emergence of a a computer on a chip had been predicted by electronics engineers for years, but the prevailing view in 1971 was still that integrated circuit technology was not yet sufficiently advanced for it to be practical. However, Ted Hoff, an Intel engineer, felt differently; he was perhaps the first person to recognize that the new silicon-gated MOS (metal oxide semiconductor) technology might make a single-chip CPU possible.

The origin of the 4004 can be traced back to late 1969 when Busicom, a Japanese company, requested the design of twelve custom chips for functions such as keyboard scanning, display control and printer control for a calculator that it was planning. Hoff determined that Intel could build a single, general purpose logic chip to do the work of these twelve. Intel and Busicom soon agreed and provided funding for it.

The design team was headed by Federico Faggin, and the software for the chip was written by Stanley Mazor. Work was completed nine months later.

The 4004 measured one eighth of inch wide by one sixth of an inch long and contained 2,300 MOS transistors. It had a four bit word length and a then impressive speed of speed of 108KHz. Functional blocks included an address register and address incrementer, an index register, a four-bit adder, an instruction register, and decoder and control peripheral circuitry. A register is a very small amount of built-in, high speed memory.

Despite its tiny size, the 4004 had as much computational power as ENIAC (Electronic Numerical Integrator And Computer), which contained 17,468 vacuum tubes, 70,000 resistors and numerous other components and weighed roughly 30 metric tons. Completed in 1945, ENIAC was the world's first first general purpose programmable electronic computer.

Intel also supplied a family of custom support chips for the 4004 that added greatly to its flexibility and usefulness. Among them were the 4001, which was a 256-byte ROM (read-only memory), the 4002, which was a 40-byte RAM (random access memory), the 4003, which was a 10-bit parallel output shift register for scanning keyboards, displays, printers, etc., and the 4008, which was an 8-bit address latch for access to standard memory chips.

The 4004 was the first microprocessor designed and manufactured by Intel. It was followed the next year by the world's first eight-bit microprocessor, the 8008, which contained 3,300 transistors (and the 4040, a revised version of the 4004). Today the Santa Clara, California-based Intel Corporation is the world's largest producer of microprocessors, and it is also the largest manufacturer of semiconductor devices as a whole.

Created May 3, 2006.
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