The history of the processor, part I

The 4004

Three years after Intel was started they succeeded in finishing the first microprocessor. In 1971 the Intel 4004 is produced; teh IC consists of around 2250 transistors and operates at the speed of 108 KHz. The possibilities of this chip were no more than being able to use in a simple calculator, but it was a revolutionary product at the time. Untill then people needed big rooms full of loose transistors to do what a simple calculator can do now. In 1972 the 4 bit 4004 is replaced by the 8 bit 8008, and from there on things start moving at a very rapid pace.

One of the missions that Gorden Moore gave himself was developing computers that people could use at home. Intels next processor that appeared in 1974, the 8080, was the basis for the first "Personal Computer", the Altair 8800. The Altair was developed by an American company that was on the brink of bankrupcy, MITS. The price for the computer was $ 397, quite a large sum at the time. MITS bought the processors of Intel for 75 dollars each. Intel initially set the price for teh 8080 at 360 dollars, which was a sneer at IBM, that sold IBM 360 mainframe computers that cost millions of dollars. The Popular Electronics magazine wrote an article about the first personal computer, which caused a rush on the Altair 8800. Where MITS was very close to bankrupcy and PC's were non-existent, all of a sudden they sold an average of around 200 personal computers a day.

Important detail: Operating software did not exist in 1974, buyers of the 8800 has to learn to operate the machine themselves. A bit later two men, Paul Allen and Bill Gates, developed the basic programming language for the Altair 8800. A year after that they founded the company Microsoft, in order to develop an operating system for the first IBM PC, the predecessor of the modern PC as we know it now.

The first x86-processor: 8086

In 1977 Ken Olsen, founder of Digital (Digital was taken over by Compaq) made a memorable statement :“There is no reason why anyone would want a computer in their home.” Only a year later in 1978 he had to realise that his statement could not be further away from the truth. Intel introduces the first "real" processor, the 8086, consisting of 29.000 transistors and operating at 4.77MHz.

The instruction set used for the 8086 is named x86, and all successors to this processor are still based on and compatible with this instruction set. The 8086 sports 20 address lines, and is able to address 1 Megabyte of memory. A huge amount, as the first computers based on this processors came with only 16 kilobyte of memory. To enable the production of a cheaper PC Intel introduces a second version of the processor, the 8088. The 8088 has an 8 bits databus and can be used with cheaper memory than the 8086. IBM decides to use the 8088 in their first computer for home use, the Personal Computer, together with an operating system developed by Microsoft, DOS (Disk Operating System)

The First x86-processor: Intel's 8086/88. Even the latest processors are still compatible with software written for this processor in 1978.

A IBM XT from the early eighties with an Intel 8088 processor, 640 kB memory, 20 MB harddisk and EGA 16-color monitor.

The Intel 8088 lasts for quite a few years, but the other parts of the PC start evolving. The first IBM PC came wth 16kB memory, 160 kB floppydrive, no hard drive and a monochrome monitor. In the eary eighties however models appeared with 640kB memory, 20MB hard drive and a 16 color EGA monitor. The 4.77 Mhz processor was becoming a bottleneck, and even increasing its speed to 8MHz was not enough.

It's immediate successor was the 80186, however this was never widely used in persnal computers. The 80186 ran at a higher clockspeed and sported an onboard system- and interrupt controller. The processor was very popular in industrial applications, however the true sucessor for Personal Computers came when the 80286 was introduced. The public quickly took to this processor and called it 286 (two-eightysix).

x86 through the years

The clock frequency of the first x86 processor was a whopping 4.77MHz, no less than 750 times lower than the faster Pentium 4 chip released (3.8GHz). If you consider the fact as well that current processors are capable of handling more than one instruction per clockcycle through the use of pipelines and execution units, the 8086 needed 12 clockcycles to finish one instruction. It is sagfe to say that modern processors are more than 10.000 faster than the original 8086. The number of transistors per chip has grown, as you can see on the graph on the revious page. the 8086 has 29.000, the Pentium 4 has 125 million and the Pentium D pressler has 376 million transistors. The production process has made equally impressive steps, the 8086 was produced using a 3 micrometer process, the newer processor are produced on a 65 nanometer (or 0,065 micrometer); the transistors on the current Pentium processors are 46 times smaller than on the 8086!