The First Microprocessor: Intel 4004

The First Microprocessor: Intel 4004

A microprocessor is a programmable set of integrated circuits, they are the reason the computers nowadays are compact, consume less power, faster, highly reliable, generate
less heat. So, lets look at the microprocessor that started it all the Intel 4004.

Early computers (2nd gen) used transistors from as early as 1940s, but the drawbacks were it took up a large amount of space, and required a cooling system and were costly
and not versatile. By the end of the 60s engineers found a way to combine multiple transistor into a single IC. Although this reduced the size of the computers compared to
the earlier ones. They still needed numerous chips to function.

The use of MOS(metal-oxide semiconductor) ICs in computers paved the way for the first microprocessor. At first the MOS transistors were slower and unreliable compared to their
bi-polar counterparts. Hence they were used to design computers only when performance was not the top priority. The first computer designed using the MOS technology was the
24-bit general-purpose computer D2000 used for aviation and navigation. It was very compatible , and was used for guidance on the Poseidon submarine-launched missile.

In the late 1960s a Massachusetts-based start-up called Viatron Computer Systems announced its System 21, a 16-bit minicomputer built from MOS chips. The
System 21 was aimed, among others, at applications such as mathematical and statistical analysis, business data processing, data entry and media conversion, and
educational/classroom use. Viatron introduced the term "microprocessor" in 1968, although they were referring to their 2101 terminal and not a chip as we know it. It was a
terminal which was made of 18 MOS chips on three separate boards.

In 1971, BusiCom, a Japanese calculator maker partnered with Intel, an American semiconductor company to design a multi-chip calculator. The 4004, created by Federico
Faggin who led the project from its beginning to completion. Marcian Hoff formulated and led the architectural proposal in 1969, and Masatoshi Shima contributed to the architecture
and later to the logic design. The end result was a 4-bit wide single chip CPU and the first micro-processor Intel 4004. The BusiCom calculator 141-PF came out soon after. The Intel
4004 microprocessor was also used in the first microprocessor-controlled pinball game, a prototype produced by Dave Nutting Associates for Bally in 1974.

intel 4004.jpg

The 4004 marked the start of the dominance of Intel in the semiconductor industry and was the most advanced IC in its time.

• Features of the Intel 4004 o Maximum clock rate : 740 kHz. o Instruction cycle time : minimum 10.8 μs. o Instruction execution time : 1 or 2 machine cycles (10.8 or 21.6 μs), 46250 to 92500 instructions per second. o Transistors : 2300 o Core count : 1 o Separate program and data storage. o Can directly address 640 bytes of RAM. o Can directly address 32,768 bits of ROM. o Instruction set contains 46 instructions. o Register set contains 16 registers of 4 bits each. o Internal subroutine stack, 3 levels deep. o Circuit line width : 10microns.

Written by  K Sriram
on December 6th, 2021


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