1950S—Transistors
Transistors performed functions similar to vacuum tubes but they were smaller, cheaper, and more reliable. Additionally, they consumed less power. The ability for transistors to replace vacuum tubes was first demonstrated in AT&T’s Bell Laboratories. Transistor-based computers could perform 200,000 to 250,000 calculations per second.
Transistors are also used in other electrical devices such as the radio. Below is a picture of a radio and transistors.
Figure 4 Transistors
1960S—Integrated Circuits
An integrated circuit, also called a "microchip" or "chip," is a thin slice of silicon packed with microscopic circuit elements such as wires, transistors, capacitors, and resistors. It was developed in 1958 by Jack Kilby at Texas Instruments and independently by Robert Noyce at Fairchild Semiconductor. Integrated circuits enabled the equivalent of thousands of vacuum tubes or transistors to be packed onto a single miniature chip about the size of your fingernail, reducing the physical size, weight, and power requirements for devices such as computers. Computers became ever smaller as more components could fit onto the chip. More information about the IC chip can be found at the Smithsonian Institute's Jerome and Dorothy Lemelson Center for the Study of Invention and Innovation.
1970S 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. The figure below shows the number of transistors on a microchip increasing exponentially. More about Moore’s Law will be explained in page 2.5.1 Moore’s Law.
Figure 7 Moore's Law applied to Intel processors [Moore's Law, The Future - Technology & Research at Intel]
|
|
Year of Introduction |
Transistors |
|
4004 |
1971 |
2,250 |
|
8008 |
1972 |
2,500 |
|
8080 |
1974 |
5,000 |
|
8086 |
1978 |
29,000 |
|
286 |
1982 |
120,000 |
|
386TM processor |
1985 |
275,000 |
|
486TM DX processor |
1989 |
1,180,000 |
|
Pentium® processor |
1993 |
3,100,000 |
|
Pentium II processor |
1997 |
7,500,000 |
|
Pentium III processor |
1999 |
24,000,000 |
|
Pentium 4 processor |
2000 |
42,000,000 |
|
Itanium 2 processor |
2002 |
220,000,000 |
Table 1 Number of transistors used in Intel processors over the years [Intel Research Site]