The most commonly-used microprocessors are IBM PC compatibles and Macintoshes. In general, the chips powering PCs are made by Intel Corporation. Advanced Micro Devices (AMD), Cyrix Corporation, and other firms make Intel-compatible chips.
The IBM PC was introduced in 1981. It used a 16-bit processor Intel 8088 running initially at 4.77 MHz. A major limitation of this processor was its maximum memory size of IMB. Another limitation was that programs could directly access the computer’s memory. One program might overwrite the other one’s portion of memory, causing a crash.
To solve this problem, Intel introduced the 80286. It worked with two modes. The first mode was called real mode. The second mode was called protected mode. It introduced two major technical improvements. In protected mode, programs could use up to a gigabyte of RAM. Also, the processor gave programs a certain section of memory and prevented other programs from trying to use this section. This allocation reduced the number of system failures when users tried to run more than one program. The 80286 was followed by the 80386, also called the 386, Intel’s first 32-bit microprocessor.
MS-DOS, runs in real mode and cannot take advantage of the benefits of protected mode. Microsoft Windows has the capability to switch the 80386 and later processors into protected mode. It enables the users to make full use of more than 640KB of memory and providing protection for multitasking. Multitasking enables the processor to run more than one program at once by switching among them.
In 1993, Intel released the first Pentium microprocessors that used a 64-bit data bus. Pentium is derived from the Latin word for five. The Pentium chip was followed by the Pentium Pro. It was an advanced Pentium design for use in servers and engineering workstations. In 1997, the Pentium MMX was introduced. It contained a new set of 57 multimedia instructions. These instructions enabled Pentium MMX-based systems to run games and multimedia applications more quickly.
In 1998, the first Pentium II processor was released that incorporated the Pentium Pro’s advanced design as well as MMX graphics and the game’s circuitry of earlier chips. A low-priced version of the Pentium I] was called Celeron. It reduced costs by cutting down on the amount of secondary cache. An advanced version of the Pentium II, the Xeon, was designed for professional applications. In 1999, Intel released the Pentium III. It was an upgraded version of the Pentium II with clock speeds of up to 1000 MHz (1 gigahertz). However, Intel’s main competitor, Advanced Micro Devices (AMD), beat Intel to the 1-gigahertz mark with the company’s Athlon processor.
Motorola Corporation provides the CPU for Macintoshes. They fall into two processor families: 68000 series (68000 to 68040) and PowerPC family. PowerPC microprocessors are RISC chips that run earlier Macintosh software: The following shows how these processors have improved. Apple Computer gives its own name to the PowerPC chips. Motorola’s 750 is the same thing as Apple’s G3 and Motorola’s 7400 becomes the G4. in Apple’s marketing.
Benchmarking is a technique used to evaluate how various computers will be able to handle the workload of a particular organization. A sample of the organization’s regular computing jobs is run on the new systems that are being considered. Benchmarking can provide comparison information for selecting or configuring computer systems. However, it may be difficult to get existing jobs to run on target machines due to incompatible formats and difficult to compare the final results between various computers.