A microprocessor,also known as a CPU or central processing unit, is a silicon chip made from very small transistors and other circuit elements on a single semiconductor integrated circuit (IC). At the heart of all personal computers and most workstations sits a microprocessor. Microprocessors also control the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles.
The first microprocessor to make it into a personal computer was the Intel 8080, a complete 8-bit computer on one chip, introduced in 1974. The evolution of microprocessors have been known to follow Moore's Law when it comes to steadily increasing performance over the years. The following table lists the evalution of Intel microprocessors:
| Name | Date | Transistors | Microns | Clock speed | Data width | MIPS |
| 8080 | 1974 | 6,000 | 6 | 2 MHz | 8 bits | 0.64 |
| 8088 | 1979 | 29,000 | 3 | 5 MHz | 16 bits 8-bit bus |
0.33 |
| 80286 | 1982 | 134,000 | 1.5 | 6 MHz | 16 bits | 1 |
| 80386 | 1985 | 275,000 | 1.5 | 16 MHz | 32 bits | 5 |
| 80486 | 1989 | 1,200,000 | 1 | 25 MHz | 32 bits | 20 |
| Pentium | 1993 | 3,100,000 | 0.8 | 60 MHz | 32 bits 64-bit bus |
100 |
| Pentium II | 1997 | 7,500,000 | 0.35 | 233 MHz | 32 bits 64-bit bus |
~300 |
| Pentium III | 1999 | 9,500,000 | 0.25 | 450 MHz | 32 bits 64-bit bus |
~510 |
| Pentium 4 | 2000 | 42,000,000 | 0.18 | 1.5 GHz | 32 bits 64-bit bus |
~1,700 |
| Pentium 4 "Prescott" | 2004 | 125,000,000 | 0.09 | 3.6 GHz | 32 bits 64-bit bus |
~7,000 |
There are three basic characteristics for microprocessors (CPUs):
- Instruction set: The set of instructions that the microprocessor can execute. For example, RISC (reduced instruction set computer) or CISC (complex instruction set computer).
- Bandwidth: The number of bits processed in a single instruction.
- Clock speed: Given in megahertz (MHz), the clock speed determines how many instructions per second the processor can execute.
The higher the value of bandwidth and clock speed, the more powerful the CPU (microprocessor). For example, a 32-bit microprocessor that runs at 200MHz is more powerful than a 16-bit microprocessor that runs at 100MHz.
Microprocessor and CPU (Central Processing Unit)
Related Terms: Integrated Circuit (IC), RISC, CISC, Bandwidth, MIPS, Transistors