When you have finished this project, you will be able to:
	describe computer system components
	define serial and direct access
	outline recent developments in computer architecture
	describe the following terms: RAM ROM CPU bit byte Herz kilo, mega, and giga

Understanding the parts of a computer system, how they work, and the function of them is important in order for you to communicate with other computer users, computer vendors, and if you will be pursuing any field related to computers, your colleagues. While this project will not provide you with the engineering level details of computing systems, you will learn some terminology and gain some valuable knowledge about the inner workings of a computer. As you work through this project, keep in mind that although the information about computer components is presented as if each were a unique entity, no single component is useful without all of the other components. So the general approach to learning about computer architecture will be to present components, then discuss the sum of the components in a system.

Hardware and Software

A computer system can be classified into two major items. Hardware which is the physical component of a computer system, and software which allows the hardware to operate. Although very much interconnected, each will be dealt with separately.

Hardware

The CPU and the the Computing Cycle

In order for all of the hardware components to work together, a Central Processing Unit (CPU) is required. The CPU is the "brain" of the computer, and the place where all of the instructions a computer receives are processed. The CPU is analogous to the human brain - millions of instructions are received, processed, stored, and sent out again. The illustration below shows the circular nature of the processing cycle.

All computers operate in a similar way by performing four basic operations. Together, these operations are called the information processing cycle and are:

• input
• process
• output
• storage

Everything a computer does is required to go through this process. The raw material of a computer is called data, and can be the raw facts, including numbers, words, images, and sounds that are given to the computer during the input part of the cycle. Once the data is in the computer, it is processed in order to turn it into some useful form, such as a document. In order to see the information (or hear it), it enters the output operation, and may appear on paper, on a monitor, or through speakers. Sometimes the information is stored for use later on.

A Look Inside

The illustration below shows the inside of a computer. You can refer back to this illustration as you work through this project.

The CPU, and many other components, are mounted on a large circuit board called a mother board. All devices that the computer communicates with must somehow be connected to the mother board. A good motherboard will allow for the addition of accessories and other components. The picture below shows a typical motherboard.

Processing

All processing is done by the Central Processing Unit (CPU), and the CPU is the "brain" of the computer. CPUs are designated by their processor number. You may be familiar with names such as Intel Pentium, or Intel Pentium III, or Intel '486. These numbers indicate that the chip was manufactured by the Intel Corporation, and that is is a Pentium III CPU, for example. If you are familiar with Macintosh computers, then you might know that computer uses the Motorola G4 CPU. The higher the number, the faster the CPU works. The picture below shows Intel CPU chips. The one on the far right shows the bottom opf the chip, which is where the connection to the computer occurs. The actual CPUs are much smaller than what is shown, but are mounted on a base so they can be connected to the computer.

Another factor in the rating of the CPU is the "clock speed", which is measured in MegaHerz. The greater the MegaHerz, the faster the CPU can process information. When you purchase a computer, you should look for the highest speed processor you can afford.

Located on or attached to the motherboard are several components that a computer needs to operate. The most important of these will be discussed.

Random Access Memory

Random Access Memory (RAM) is what is known as volatile memory - it is active and useful only when the computer is turned on. Once the computer is turned off or re-started, the information stored in RAM is lost. Therefore, RAM is temporary memory and is used by the computer for working storage. If you are working on a word processing document, the document is in RAM while you are working on it. When you save the file, it is transferred from RAM to a storage device of some type.

RAM is measured in megabytes, and the larger the RAM, the better your computer will run.

Read Only Memory

Read Only Memory (ROM) is used by the computer for basic machine level operations - such as how to boot up. The ROM is programmed by the manufacturer, and generally can not be changed.

Expansion Slots and Cards
Expansion slots allow a user to add peripherals and components to a computer. Expansion slots are designed to accept expansion cards, which in turn connect to other components. Expansion slots are called busses, and there are two terms related to the bus. The first is the bus width - how much data the slot can accept at one time. The higher the bus width the more data that can be processed. Bus width is measured in bits. The other term is bus speed. The faster the bus, the more data it can receive and send. Bus speed is measured in megaherz (MHz).

There are two major standards for expansion cards: ISA and PCI. ISA is an acronym for Industry Standard Architecture and is an older industry standard. It is slower than other expansion slots. An ISA bus has a width of 16 bits and a speed of 8 MHz.

PCI stands for Peripheral Component Interconnect and is a faster standard than ISA. The PCI bus width is either 32 or 64 bits and can have speeds up to 64 MHz. In addition, PCI supports the Windows Plug-and-play standard thus making it easier to connect peripheral devices.

Input devices

Input devices are anything that can provide data for the computer. Examples of input devices are the keyboard, mouse, a scanner (which converts analog data to digital data), and a bar code reader. Some items, such as a monitor with a touch screen can be both input and output devices. The technical details of how each of the input devices works will not be discussed here - you should simply understand how they are used from a user's point of view.

The most common input device is the keyboard, and until voice recognition software becomes commonplace, it will remain the most important input device. The illustration below shows a typical keyboard, although there are many variations on this.

An important input device in environments that use a graphical user interface (GUI), such as Windows or Macintosh is the mouse. The mouse is sometimes called a pointing device, but it does provide input for a computer.

A less common input device is a scanner. A scanner is used to change analog images or text into digital information. For example, a photograph that needs to be published on the Web can be scanned and easily displayed on a Web page. In a similar manner, a printed page can be scanned, processed with optical character recognition software (OCR) and placed in a word processing program without any need to re-type the document. You will learn more about OCR and word processing software later.

Output Devices

Output devices are those devices that allow you to see, in human recognizable form, what the computer has done. Examples of output devices include a monitor and printer. A monitor allows you to see what you are doing with the computer, or the results of your input. Because you will spend so much time looking at the monitor, it is important that you understand some important features of it.

The most obvious feature of a monitor is the size. The larger the monitor, the more of what you are doing you can see - or the larger the image of what you are doing. But, larger monitors come with a larger price tag. The size of a monitor is measured diagonally across the screen - be careful though; manufacturers usually provide you with the diagonal measurement which is less than the actual viewing area. Another important consideration when purchasing a monitor is the dot pitch - the distance between the small dots on the screen. The smaller the dot pitch of a monitor, the sharper the image. Be sure to choose a monitor with a dot pitch of 0.28 mm or less. Some monitors appear to flicker when you use them, and this could possible cause eye strain. When purchasing a monitor, be sure to look for a non-interlaced one with a high refresh rate. This will reduce flicker and be easier to look at for long periods of time.

Although there are many types of printers available, the most common monochrome printer is a laser printer. Laser printers provide the sharpest, fastest printing at a relatively low cost. If you are interested in a colour printer, then you may have to settle for an ink jet printer. Ink jet printers are not as sharp as laser printers, but are somewhat cheaper, especially if you are purchasing a color printer.

Storage Devices

Storage devices are devices that store your software and work, either temporarily or more permanently. While you are working with your data and software, it is stored in the Random Access Memory (RAM). However, as you learned earlier, RAM is on temporary and is lost when the computer is shut down. In order to use data at a later time, it needs to be stored on a different medium. A floppy drive is an example of this type of medium. However, floppy drives are limited to the amount of data they can store.

A more popular solution is to use a hard drive, which is usually built into the computer. A hard drive can store many software programs, and your data. Hard drives are measured by the amount of data they can store. The more capacity, the more programs and data you can store - but the more they cost. Current hard drives can store 8 MB or more.

Other Peripherals
There are many other accessories you can buy for your computer depending upon your needs and your budget. In some cases, it is difficult to tell whether they are input, output, or storager devices, so they have been grouped under peripherals. Most computers now come with a compact disk read only memory (CD-ROM) drive. CD-ROMs can hold a large amount of data and are inexpensive to manufacture. Most software is supplied on a CD-ROM. However, CD-ROMs are read only devices, which means you can not save data to them unless you have a special peripheral.

Many computer users purchase a special CD-ROM drive that can also create and save data on a CD-ROM.

Another popular peripheral is a MODEM. You will learn more about MODEMs, their purpose, and how they work in another project. However, a MODEM allows you to communicate with other computers using telephone lines. If you want to connect to the Internet, you will probably use a MODEM. Many computers have a MODEM built in and attached directly to the motherboard, while others connect an external MODEM through a port on the back of the computer.

In this project, you have just touched on the many components available to a computer user. There is still much to learn, and certainly in greater technical depth than explained here. However, your computer can not work without software, and that is the subject of the next section of this project.

Software

Operating System

When a computer first starts up, it can do very little because it has few instructions build into the hardware. Instead, all computers require software to operate. This is known as operating system (OS) software, and provides the computer with instructions as to how to handle most of its functions. Examples of OS software include Windows, Macintosh, OS2, and DOS. The first three are GUIs which means the interface between the user and the computer is graphical rather than by command line.

Application

Application software is the software on a computer that provides the productivity of a computer. Examples of application software include word processors, spreadsheets, databases, email, and any other program that people generally use for work.

Utility

Utility software is used to protect a computer or make it work more efficiently. Often, utility software is built into the operating system. Examples of utility software include backup, disk compression, and virus protection programs.

Programming

Programming software might also be considered application software, but it is really a category on its own. Programming software is software that can be used to create programs that a computer could run. This Web page browser was created with programming software, and you are looking at the result of that program on the monitor. Examples of programming software include C++, Visual C++, Java, BASIC, PASCAL, and Visual Basic.

Test Your Knowledge

Your assignment for this project is to research one component - processor, input, output, or peripheral, and provide technical details about that component and prepare a buyer's guide. The final product of this report will be a Web page. If you wish, you may use this Web page for part of the Final Project for this module.