Processors
In 1971,a company called Intel that specializes in manufacturing central processing units managed to combine the arithmetic-logic unit and the control unit on a single tiny processor called microprocessor and called it Intel 4004.
This microprocessor was used in electronic calculators. The first microprocessor to be used on microcomputers was called Intel 8086 developed in 1974. Since then,there has been a tremendous growth in microprocessor technology marked by great increase in processing capability and speed.
Until 1989, Intel corporation enjoyed monopoly in the field of microprocessor technology with her famous Intel processors. Since then other players joined in and started manufacturing cheaper alternatives.These include:Advanced Micro Devices(AMD), Cyrix and Motorola companies
Processor clock speed
The speed at which a processor executes instructions is determined by its clock speed.System clock speed is measured in hertz’s(Hz). A hertz is a unit of frequency which measures the number of cycles per second in a signal.
Quantities of the clock speed can be expressed in;
1. Kilohertz(kHz):Approximately one thousand hertz’s(1000).
2. Megahertz(MHz):Approximately one million hertz’s(1000 000).
3. Gigahertz(GHz):Approximately one billion hertz’s(1000 000 000).
There has been a tremendous growth in the processing capability and clock speed of microprocessors.From a speed lower than 4MHz, modern microcomputers can run at speeds higher 2GHz. The table below shows a summary
of how microprocessors have evolved.
| Processor | Description | Clock Speed |
| Intel 8086 and 8088 | The two are almost identical and were used with the first IBM PCs .8086 was an improvement of 8088. | 4.7 MHz -10 MHz |
| Intel 80286 over 8086. | Provided increased performance | 6 MHz-20 MHz |
| Intel 80386 SX |
This was the processor that opened up the PCs to many users. Apart from Intel's 80286,AMD produced and their versions with copied greatly the Intel's. |
33 MHz-40 MHz |
| Intel 80368 DX 80486 SX and 80486 DX |
These were the first entry in the processor market. AMD and Cyrix produced their version too. |
25 MHz-50 MHz |
| Pentiums (586) and above | Since 1992,Intel decided to coin their fifth generation with the name Pentium instead of 80586.Pent is a Latin word that means five. Intel chose the word in order to distinguish its 80586 and above processors from AMD and Cyrix versions i.e. 5x86 and AMD K5 respectively. Examples of Intel Pentium processor are Pentium Pro,Pentium MMX ,Pentium II and currently Pentium IV at the time of writing this book |
60 MHz-presently Pentium IV-with over 2.8 GHz |