Section 1.2. Hardware


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1.2. Hardware

Computer systems, whether large or small, multi-user or single-user, expensive or cheap, include most of the following pieces of hardware:

1.2.1. Central Processing Unit (CPU)

This reads machine code (instructions in a form that a computer can understand) from memory and executes it. A CPU is often likened to the "brain" of a computer.

1.2.2. Bus

This is the connection, or data path, between the CPU and the system memory and devices of a computer system. All data that moves from a disk drive into memory, or from memory to the CPU, travels across the system's bus.

1.2.3. Random Access Memory (RAM)

This holds the machine code and data that are accessed by the CPU. RAM normally forgets everything it holds when the power is turned off.

1.2.4. Read-Only Memory (ROM)

This holds both machine code and data. Its contents may not be changed and are remembered even when the power is turned off.

1.2.5. Disk(s)

These hold large amounts of data and code on a magnetic or optical medium, and remember it all even when the power is turned off. Floppy disks are generally removable, whereas hard disks are not. Hard disks can hold a lot more information than floppy disks.

1.2.6. CD-ROM Drives

These allow digitally published information on a compact disc to be read by the computer. The information may be in a data stream or may constitute a file system that the operating system can read as if it were on a hard disk drive.

1.2.7. Monitor(s)

These display information and come in two flavors: monochrome and color. Monochrome monitors are rare in newer computer systems.

1.2.8. Graphics Card(s)

These allow the CPU to display information on a monitor. Many graphics cards have on-board processors to decrease the load on the system processor.

1.2.9. Keyboard

This allows a user to enter alphanumeric information. There are several different kinds of keyboards available, depending partly on the language of the user. For example, Japanese keyboards are much larger than Western keyboards, as their alphabet is much larger. The Western keyboards are often referred to as QWERTY keyboards, as these are the first six letters on the upper left-hand side of the keyboard.


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1.2.10. Mouse

This allows a user to position things easily on the screen using short movements of the hand. Most mice have "tails" that connect them to the computer, but some have radio or infrared connections that make the tail unnecessary.

1.2.11. Printer(s)

These allow a user to obtain hard copies of information. Some printers print characters only, whereas others may print graphics.

1.2.12. Tape(s)

These are generally used for making backup copies of information stored on disks. They are slower than disks but store large amounts of data in a fairly cheap way.

1.2.13. Modem

A modem allows you to communicate with other computers across a telephone line. Different modems allow different rates of communication. Most modems even correct for errors that are caused by a poor telephone connection.

1.2.14. Network Interface

A network interface card (NIC) allows your computer to communicate with other computers across a high-speed link.

1.2.15. Other Peripherals

There are many other kinds of peripherals that computer systems can support, including graphics tablets, optical scanners, array processors, sound cards, voice recognition cards, and synthesizers (to name a few).

You cannot just connect these pieces of hardware together and have a working computer systemyou must also have some software that controls and coordinates it all. The ability to share peripherals, to share memory, to communicate between machines, and to run more than one program at a time is made possible by a special kind of program called an operating system.




Linux for Programmers and Users
Linux for Programmers and Users
ISBN: 0131857487
EAN: 2147483647
Year: 2007
Pages: 339

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