hardware / component devices

Component Devices:

A typical set of internal components for a computer would include the following:

Microprocessor, Processor Fan, Memory, Hard Drive, CD-Rom/DVD Drive, Floppy Drive, Graphics Card, Sound Card, USB Card, Modem, Power Supply, Parallel Cable, Mother Board (with connections for the components and peripherals), and a Metal Case with buttons and LED lights.

Microprocessor: A silicon chip that contains a Central Processing Unit. At the heart of all personalcomputers 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.

Speed: Microprocessors are measured by the speed that they execute instructions. Every computer contains an internal clock that regulates the rate at which instructions are executed and synchronizes all the various computer components. The faster the clock, the more instructions the CPU can execute per second. Clock speeds are expressed in megahertz (MHz) or gigahertz (GHz).

Pentium: A 32-bit microprocessor introduced by Intel in 1993. It contained 3.3 million transistors, but has been superseded by the Pentium Pro, the Pentium II, the Pentium III, and now the Pentium 4 microprocessor.

Cache: Is a small memory store where the processor can access instructions fast, it is located between the microprocessor and memory, usually part of the microprocessor chip. Memory caching is effective because most programs access the same data or instructions over and over.

Comparisons:

	Intel Celeron	Intel Pentium P4	AMD Athlon K7	Power PC G4 Apple
Transistors	7,500,000	55,000,000	22,000,000	10,500,000
Speed	2GH	2.4GH	1.2GH	800MH
Cache	256kb	256kb	256kb	1Mb

Microprossor Fan: Microprocessors run very hot, although there is some heat dissipation in the design of the casing all microprocessors need assistance with cooling by using a fan.

Memory: Random Access Memory RAM can be accessed randomly and is the common memory available for computer programs to run in. A computer with 128Mb of RAM has approximately 128 million bytes of memory that programs can use. RAM memory is volatile, meaning that any data stored is lost when the power is turned off.

Read-Only Memory ROM is memory on which data has been prerecorded, it cannot be removed and can only be read. ROM memory is nonvolatile, meaning the data is retained when the power is turned off. ROM stores the program that boots the computer (starts the operating system).

Hard Disk Drive: A magnetic disk on which you can store computer data, read data and write data.

Hard disks hold more data and are faster than floppy disks. A hard disk, for example, can store anywhere from 10 to more than 100 gigabytes Gb of data, whereas most floppies have a maximum storage capacity of 1.4 megabytes Mb.
A single hard disk usually consists of several platters. Each platter requires two read/write heads, one for each side. All the read/write heads are attached to a single access arm so that they cannot move independently. Each platter has the same number of tracks, and a track location that cuts across all platters is called a cylinder.

CD Rom/DVD Drive: Is the device that plays a Compact Disk- Read Only Memory, CD-ROM.

CD-ROMs are used to store computer data as read-only, which means that once the data has been recorded onto them, they can only be read, or played. Newer drives can write data once to a CD, known as a CD-R, or can re-write data to a CD over and over again, known as a CD-RW. Typical amount of storage is 650Mb. A DVD (digital versatile disc or digital video disc) looks similar to a CD-ROM but can hold much more data, from 4.7Gb to 17Gb. DVDs are commonly used as a medium for digital representation of movies and other multimedia presentations that combine sound with graphics. DVD drives may also be capable of writing once, DVD+R, and rewriting over and over again, DVD+RW.

Floppy Disk Drive: FDD, a disk drive that can read data from and write to soft magnetic floppy disks. Floppy disks are slower to access than hard disks and have less storage capacity, normally 1.4MB, but they are much less expensive, and most importantly, they are portable and still very popular.

Other types of disk are Zip disks which are higher capacity than floppy disks, they are used in business and are popular as they can be transferred between computers easily.

Graphics Card: Also called a Video Adapter, is a circuit board that plugs into an expansion slot inside

the personal computer to give it display capabilities, (that is seen on the monitor).The two basic video modes are text, for ASCII characters; and graphics, for Bit-Mapped images. A Graphics card will contain memory so that the computer's RAM is not used for storing displays. In addition, newer cards have their own graphics coprocessor, known as a graphics accelerator, for performing graphics calculations.

Sound Card: Is a circuit board that plugs into an expansion slot inside the personal computer to give it

sounds (that is heard on the speakers). Sound cards are necessary for nearly all CD-ROMs using multimedia. Sound cards often have connections for devices that can be used for games. Sound cards can also be used to record sound input from a microphone connected to the computer. Sound cards convert digital data to analogue sound and vice versa.

USB Card: Universal Serial Bus, the new device for connecting peripheral devices. It is very fast, it is plug and play, (no need for loading drivers), and will eventually replace Serial and Parallel connections.

Modem: Is a circuit board that plugs into an expansion slot inside the personal computer to enable a

computer to transmit data over telephone or cable lines. Computer information is stored digitally, but the telephone lines use analogue sound waves. A modem converts digital data to analogue sound when sending data and vice versa when receiving data. A modem is essential to use the Internet and to send and receive e-mails.

Power Supply: For the power to run the computer. Leads from the power supply box go to the

Motherboard, the Hard Drive, the Floppy Drive, the CD-ROM, and other devices. The electricity supply is transformed from 250 volts to down to a smaller 3.3 - 5 volts.

Parallel Cable: Some devices are already connected to the motherboard using the expansion slots.

Other peripheral devices are plugged directly into the motherboard. Some devices need parallel cable to connect them to the motherboard.

Motherboard: Is the main circuit board of a computer. The motherboard contains the connectors for

attaching additional circuits boards and devices. The motherboard is a large complex circuit board containing chips and circuits connecting the microprocessor to all other devices, all the chips that reside on the motherboard are known as the motherboard's chipset.

Metal Case: A stylish attractive case to protect all of the internal components.