1945
The ENIAC is revealed to the public. It is considered the world's first electronic, digital, general-purpose computer. It uses 18,000 vacuum tubes as the main logic component of its processing un
1956
The transistor replaces the vacuum tube as the main logic component of the processing unit.
1964
Several transistors are integrated together on a single wafer of silicon making the world's first integrated ciruit (IC).
 

Before 1971 the CPU in most computers is made from electronic components spread across multiple circuit boards.

1971
Intel combines all the essential components of the processing unit onto a single IC. It is called the 4004 and it combines 2,300 transistors onto a single waffer of silicon.
1976
The Z80 microprocessor is released by Zilog It is an 8-bit microprocessor that runs at 2.5 MHz. It is considered superior to Intel's 8080 (introduced in 1974) in part because several engineers left Intel to work on this project for Zilog.
1977
Steve Jobs and Steve Wozniak introduce the Apple II 'home computer'. It is based on the Motorola 6502 microprocessor.
1978
The Intel 8086 microprocessor is released. It is an 8-bit CPU running at 4.77 Megahertz. There are 29,000 transistors built onto this chip.
1981
IBM introduces the IBM-PC (Personal Computer) using the 8086 CPU. Soon nearly all the other makers of microcomputers will switch to the 8086 architecture. These machines are called IBM-compatible computers
1982
Intel introduces the 80286 microprocessor. It is the second-generation chip after the 8086. This is a 16-bit processor running at 20 MHz with 134,000 transistors.
1985
The 80386 CPU from Intel is the third-generation CPU in the 'x86' family. It is a 32-bit machine running at 16 MHz with 275,000 transistors.
1986
To boost sales of low-end computers, Intel releases the 80386SX. It runs internally at 32-bits but only has a 16-bit data bus and is sold at lower prices.
1986
To boost sales of low-end computers, Intel releases the 80386SX. It runs internally at 32-bits but only has a 16-bit data bus and is sold at lower prices.
1989
The 25 MHz 80486 is released with several new features. A math co-processor is built into the microprocessor for the first time. (Math co-processors were available before the 486, but as separate chips-the 8087, 80287, and 80387).
1992
80486DX2: The internal speed of the CPU is doubled (DX2) to 50 MHz.
1993
Intel introduces its fifth-generation CPU, the Pentium. Since Intel cannot register '586' as a trademark, they choose the name Pentium (derived from the Greek word pente for FIVE). The Pentium is a 64-bit chip with 3.1 million transistors. An internal clock speed of 60 MHz is soon increased to 66 MHz.
1994
80486DX4 boosts performance by doubling the internal speed again. The DX4 has a 100 MHz clock speed. !
1995
The first of a series of sixth generation CPUs (686) is released from Intel called the Pentium Pro. High prices and stiff competitions limit the success of this new microprocessor.
1996
Introduction of MMX to the Pentium chip. MMX is a MultiMedia eXtension to the CPUs instruction set. This enables the processor to handle graphics and other intensive multimedia operations faster. Internal speed of this new Pentium is 233 MHz although it still only communicates with the motherboard at a bus speed of 33 MHz.
1997
Intel releases the Pentium II (a 64-bit, 300 MHz CPU with 7.5 transistors).
1999
The Pentium III is another sixth generation chip with enhanced features. Running internally at 400 MHz when released it had a top bus speed of only 100 MHz. With 9.5 million transistors this 64-bit CPU includes 32 Kb of Level 1 cache.
2000
With the Pentium 4, Intel breaks past the 1 GigaHertz speed barrier. Initially rated at 1.4 GHz, this 42 million transistor microprocessor was released at 2 GHz by the summer of 2001.
2001
 
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