S to Present—Microprocessor

The microprocessor combined components of a computer on a microchip. Before the microprocessor was developed, each integrated circuit had to be manufactured for a particular purpose, but now a microprocessor can be manufactured and then programmed for various purposes to other needs. Below is a picture of a microprocessor. Note that millions of wires are etched onto an area the size of a fingernail.

Figure 6 Microprocessor chip

The first general-purpose microprocessor was the Intel 4004. It was developed in 1971 by Ted Hoff. The Intel 4004 enabled microprocessor-based computer systems to become faster, smaller, and less expensive than before.

Pace of Advancement

Transistors are still continuing to decrease in size. As transistors become smaller, more transistors can be placed on a given chip. This implies faster processing speeds and greater data storage capacity. In 1965, Gordon Moore, a founder of Intel, one of the largest microchip manufacturers, made his observation that there is an exponential growth in the number of transistors per integrated circuit. He predicted that the number of transistors that can be put on a microchip will double every 12 months, until physical limitations are reached. This observation was termed "Moore’s Law." Now the exponential growth has slowed down to doubling every 18 months, nevertheless, the rate of growth is still exponential. More about Moore’s Law will be explained in page 2.5.1 Moore’s Law. The chart below shows the rate of growth for number of transistors on microchips.

	Year of Introduction	Transistors
		2,250
		2,500
		5,000
		29,000
		120,000
386^TM processor		275,000
486^TM DX processor		1,180,000
Pentium® processor		3,100,000
Pentium II processor		7,500,000
Pentium III processor		24,000,000
Pentium 4 processor		42,000,000
Itanium 2 processor		220,000,000
Pentium D		376,000,000
Core i7		781,000,000

Table 1 Number of transistors used in Intel processors over the years [Intel Research Site]

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