The History of the CPU

Intel's first CPU, or Central Processing Unit, was a 4-bit processor, with a clock speed of 740 kHz, and was developed in November, 1971, by the computer giant, Intel.
Sources: http://www.computerhope.com/jargon/num/4004.htm

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The Intel 4004's successor, and the first 8-bit Central Processing Unit, the 8008 was available in clock speeds of 500 kHz and 800 kHz. It became the standard CPU for computers.
Sources: http://www.computerhope.com/jargon/num/8008.htm

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Again, developed by Intel, the first 16-bit microprocessor was codenamed P1, but was actually called the Intel 8086, and could run at clock speeds of 5MHz to 10MHz.
Sources: http://www.computerhope.com/jargon/num/8086.htm

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As a newer version of the Intel 80286, the 80386 was a 32-bit chip, and ran at a speed of 12MHz.
Sources: http://www.computerhope.com/jargon/num/80386.htm

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The Intel Pentium, was a 64-bit microprocessor, and was released by Intel at a hefty price of $878.00, and with clock speeds between 60MHz, and 300MHz.
Sources: http://www.computerhope.com/jargon/p/pentium.htm

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