A Brief History of Computing
- Microprocessors

© Copyright 1996-2005, Stephen White

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1971 - November 15 First microprocessor, the 4004, developed by Marcian E. Hoff for Intel, was released. It contains the equivalent of 2300 transistors and was a 4 bit processor. It is capable of around 60,000 Interactions per second (0.06 MIPs), running at a clock rate of 108KHz.
1972 - April 1 8008 Processor released by Intel.
1974 - April 1 Introduction of 8080. An 8 Bit Microprocessor from Intel.
1976? Introduction of 8085.
1976 Z80 released by Zilog, and the basis for the computer boom in the early 1980s. It was an 8 bit microprocessor. CP/M was written for the Z80 as well as software like Wordstar and dBase II - and it formed the basis for the Sinclair Spectrum of 1982.
1976 6502, 8 bit microprocessor developed and later chosen to equip the Apple II computer. Also fitted in the original Acorn machine, BBC Micro, Commodore 64 and Commodore PET.
1978 - June 8

Introduction of 8086 by Intel, the first commercially successful 16 bit processor. It was too expensive to implement in early computers, so an 8 bit version was developed (the 8088), which was chosen by IBM for the first IBM PC. This ensured the success of the x86 family of processors that succeeded the 8086 since they and their clones are used in every IBM PC compatible computer.

The available clock frequencies are 4.77, 8 and 10 MHz. It has an instruction set of about 300 operations. At introduction the fastest processor was the 8 MHz version which achieved 0.8 MIPs and contained 29,000 transistors.

1979 - June 1 Introduction of 8088, a step down from the 8086 as it contains just an 8 bit data bus - but this makes it cheaper to implement in computers.
1979 The 68000 Microprocessor launched by Motorola. Used by Apple for the Macintosh and by Atari for the ST series. Later versions of the processor include the 68020 used in the Macintosh II.
1981? Introduction of 80186/80188. These are rarely used on PCs as they incorporate a built in DMA and timer chip - and thus have register addresses incompatible with other IBM PCs.
1982 - February 1

80286 Released. It supports clock frequencies of up to 20 MHz and implements a new mode of operation, protected mode - allowing access to more memory (up to 16 Mbytes compared to 1 MB for the 8086. The virtual address space can appear to be up to 1 GB through the use of virtual memory). It includes an extended instruction set to cope with this new mode of operation.

At introduction the fastest version ran at 12.5 MHz, achieved 2.7 MIPs and contained 134,000 transistors.

1985 - October 17

80386 DX released. It supports clock frequencies of up to 33 MHz and can address up to 4 GB of memory and virtual memory of up to 64 TERABYTES! It also includes a bigger instruction set than the 80286.

At the date of release the fastest version ran at 20 MHz and achieved 6.0 MIPs. It contained 275,000 transistors.

1988 - June 16 80386 SX released as a cheaper alternative -to the 80386 DX. It had a narrower (16 bit) time multiplexed bus. This reduction in pins, and the easier integration with 16 bit devices made the cost savings.
1989 - April 10

80486 DX released by Intel. It contains the equivalent of about 1.2 million transistors. At the time of release the fastest version ran at 25 MHz and achieved up to 20 MIPs.

Later versions, such as the DX/2 and DX/4 versions achieved internal clock rates of up to 100 MHz.

1991 - April 22 80486 SX released as cheaper alternative to 80486 DX - the key difference being the lack of an integrated F.P.U.
1993 - March 22 Intel Pentium released. At the time it was only available in 60 & 66 MHz versions which achieved up to 100 MIPs, with over 3.1 million transistors.
1994 - March 7 Intel Release the 90 & 100 MHz versions of the Pentium Processor.
1994 - October 10

Intel Release the 75 MHz version of the Pentium Processor.

1995 - March 27 Intel release the 120 MHz version of the Pentium processor.
1995 - June 1 Intel release the 133 MHz version of the Pentium processor.
1995 - November 1 Pentium Pro released. At introduction it achieved a clock speed of up to 200 MHz (there were also 150, 166 and 180 MHz variants released on the same date), but is basically the same as the Pentium in terms of instruction set and capabilities. It achieves 440 MIPs and contains 5.5 million transistors - this is nearly 2400 times as many as the first microprocessor, the 4004 - and capable of 70,000 times as many instructions per second.
1996 - January 4 Intel release the 150 & 166 MHz versions of the Pentium Processor. They contain the equivalent of over 3.3 million transistors.
1996 - October 6 Intel release the 200 Mhz version of the Pentium Processor.
1997 - January 8 Intel released Pentium MMX (originally 166 and 200 Mhz versions), for games and multimedia enhancement. To most people MMX is simply another 3-letter acronym and people wearing coloured suits on Intel ads, and to programmers in meant an even further expanded instruction set that provides, amongst other functions, enhanced 64-bit support - but software needs to be specially written to work with the new functions. A major rival clone, the AMD-K6-MMX containing a similar instruction set, caused a legal challenge from Intel on the right to use the trademarked name MMX - it was not upheld.
1997 - May 7 Intel Release their Pentium II processor (233, 266 and 300 Mhz versions). It featured, as well as an increased instruction set, a much larger on-chip cache.
1997 - June 2 Intel release the 233 MHz Pentium MMX.
1998 - February Intel released of 333 MHz Pentium II processor. Code-named Deschutes these processors use the new 0.25 micron manufacturing process to run faster and generate less heat than before.
1999 - Feb 22 AMD release K6-III 400MHz version, 450 to OEMS. In some tests it outperforms soon-to-be released Intel P-III. It contains approximately 23 million transistors, and is based on 100Mhz super socket 7 motherboards, an improvement on the 66MHz buses their previous chips were based on. This helps its performance when compared to Intel's Pentium II - which also uses a 100MHz bus speed.
1999 - Nov 29 AMD release Athlon 750MHz version.
2000 - Jan 19 Transmeta launch their new 'Crusoe' chips. Designed for laptops these prvoide comparible performance to the mid-range Pentium II chips, but consume a tiny fraction of the power. They are a new and exciting competitor to Intel in the x86 market.
2000 - March 6 AMD Release the Athlon 1GHz.
2000 - March 8 Intel release very limited supplies of the 1GHz Pentium III chip.

© Copyright 1996-2004, Stephen White My homepage - email:swhite@ox.compsoc.net