Chapter 2 - Hardware and Software

PC Architecture & Performance

Processors. Microprocessors act as the computer’s brains and carry out the software commands, perform calculations, and communicate with the different hardware components needed to operate the computer. The processor speed is the speed of the microprocessor chip in your computer.

The processor plays a significant role in the performance of your computer. Intel produced one of the earliest microprocessors in 1971, called the 4004 chip. The 8086 chip produced in 1978 had 29,000 transistors and a 16-bit data bus. The Pentium chip has over 3,000,000 transistors and a 64-bit data bus. The generation of processors has evolved from the early 4004 processors to the 8088, 8086, 286, 386, 486, Pentium™ I - IV processors, and so forth. When a processor such as the Pentium IV is first introduced, it sells at a premium. If you wait a few months it usually drops in price.

The two most important characteristics of a processor are the number of bits it can process in a single instruction, (currently most processors handle 32 bits), and the speed at which it operates, (in megahertz or MHz). The higher the value, the more powerful the computer. Processors are now running over 1500 MHz per second.


















Pentium Pro







1.2 million

3.1 million

5.5. million

*The number of transistors enables new chips to do more work. - Source, Byte, December 1996.

Bit Operating System. The architecture and performance of a personal computer is partially dependent on whether the system is a 16 or 32-bit operating system. When we discuss bit operating systems, we are referring to the width of the data path. A byte, which is the same as a character, is 8 bits wide. Therefore, in a 16 bit system data is transferred two characters at a time since two bytes equals 16 bits. In a 32-bit operating system, 4 characters are transferred at a time. Whether your computer is a 16 or 32-bit system is one indication of the performance value of your computer. The underlying architecture should be designed to support the new 32-bit operating system. Windows 95/98/00™ is a 32-bit operating system. Plans are already designed to increase computers to 64 bit and then 128 bit systems.

RAM Memory. RAM is the acronym for Random Access Memory. RAM is an important element contributing to your PC’s overall performance. RAM is a temporary storage area the system uses to hold the programs or files that are currently open on your machine. A Windows program, because of its graphical user interface, requires a lot of RAM to store program data. Your CPU can only work with the data in RAM. If it fails to locate the information in your RAM, it goes to your hard drive, loads the information and then executes the commands. CPU access to RAM is very quick compared to access to the hard drive data if it has to call it forth. So if your RAM is low, it must continually look for the information on your hard drive and low RAM limits the number of programs that can be open at one time on your computer. Many programs run faster with 64-128 megabytes of RAM memory, such as video and voice recognition. Always err on the side of too much RAM.

Cache. This is memory that stores previous data screens to allow quicker retrieval speeds.

Hertz and Megahertz. Hertz is a measurement of frequency that is defined as one cycle per second. A megahertz is 1,000,000 cycles per second. Microprocessors run at speeds that are measured in MHz or millions of cycles per second. The higher the MHz, the faster the computer runs.

Bus Speed. The bus is the communication hub for the computer. Connected to it are the memory, CPU and input/output devices. The bits are routed through the bus so the speed of the bus is important to how fast the computer will run. If you have a slow bus, the speed of the processor may not make a difference.

MMX Technology. Intel’s MMX processor ( improves multimedia playback capability 20% to 80%, depending on the software and the application. It improves streaming video over the web.

Design. All computers are not designed equally. The design of the computer in terms of the RAM, bus type, and processor speeds are important in the overall performance of the computer. Benchmark tests for various manufacturers systems are routinely placed in major computer publications like PC Magazine™, Computer Shopper™ and PC Week™.