Data are received by the computer by means of input devices, such as keyboard,a mouse, a joystick, or a scanner. These devices act like the computer’s “eyes and ears.’ The input devices convert these data into a format the processor can understand.
The processor manipulates the data thereby turning it into useful information. This information is sent to an output device or storage device. Output devices include printers, monitors and speakers. It is now the job of the computer to turn this information into a format we can understand and work with, such as a picture on a screen or a printout.
Storage devices include hard disks, floppy disks, tapes and CD-ROMSs. They work two ways: they can be output devices or input devices. Information can be saved to (output) and retrieved from (input) as required.
When we talk about “hardware,” we are referring
to all the parts of a computer that can be seen and touched ; The monitor
(or screen), the keyboard and the case (the big box below the monitor).
Hardware also includes “peripherals,” the accessories which can be attached to the computer. These include a printer, a modem, an external hard drive, a mouse, and a scanner.
COMPUTER CASES: DESKTOP AND TOWER
Choosing which case is suitable to your needs depends on the size of your work area and the nature of work to be done by the computer.
DESKTOP cases are more popular and less expensive than tower cases. They are usually used at home and for fairly simple office tasks.
TOWER cases are usually found in offices and other places where more complicated computer tasks are performed and the work area is a bit limited. They cost more than the desktop but are easier to upgrade.
The case serves as the house of the processor. all
the major components of the computer are found here.
a. On/Off Switch
b. Location of hard disk drives
c. Location of drives such as floppy disk drives, CD-ROM drives and tape back-ups
d. Status Indicators- green lkght means the computer is on, yellow light means the computer is operating at its fastest speed, and red light means the hard disk is being used.
e. Keylock- locks the keyboard to prevent unathorized use of the computer
f. Reset button- Restarts the computer. Usually used when a “system crash” occurs.
g. Turbo button- when activated, shifts the computer into full speed. Use it at all times unless you’re in no hurry to finish your work
The monitor shows the visual representation of what is going on inside the computer
DOT PITCH - the size of the holes on a monitor is measured by dot pitches. The smaller the dot pitch, the better the detail dislpayed.
RESOLUTION - a monitor’s resolution is the total number of horizontal and vertical pixels (short for “picture element” ) it can display. A pixel is the smallest dot the computer can control on the screen. More pixels result in higher resolution and more detail.
SIZE - measured in inches diagonally across the screen.
ANTI-GLARE - used to reduce reflections from external light sources that can make viewing difficult. Anit-glare is usually etched on coated glass.
CONTROLS - the set of knobs usually found at the bottom of the monitor. They function like the knobs at the bottom of a television set, controlling brightness, contrast and in more advanced computers, horizontal and vertical holds.
TILT AND SWIVEL STAND - the “neck” of the computer
which allows the monitor to be moved from left to right, up and down.
** Printers print exactly what is encoded on the document to be printed. “What you see is what you get.” A print-out document is called a hard copy.**
Laser printers produce a better-quality material than ordinary printers. Hard copies from these “hi-tech” printers look very much like phototcopied material. Actually, they work pretty much like photocopiers. A laser printer “photocopies” digital pages sent by the computer.
A laser printer’s “strength” is measured by the number of pages it can print in one minute. Regular laser printers normally print six to eight pages per minute, while the faster ones can print 12 or more pages per minute.
The dot-matrix printer is the cheaper kind of printer and can be likened to and electric typewriter. But compared with the laser printer, it is a slow machine. But because of its inexpensiveness, the dot matrix is still being used in many offices and homes. It has two feeders to choose from, although it can be equipped with both: the sheet feeder and the tractor feeder.
The sheet feeder is used for one-page printouts such as office memos and short correspondence.
The tractor feeder uses continuous fan-folded paper, the type needed for long printouts such as reports and term papers.
A scanner is a computer peripheral which works
and looks like a photocopier, but instead of producing a paper copy, it
creates a file for the computer. Whatever is on the page being “scanned”
appears on the monitor where it can be edited, stored, or printed.
Scanners are used for transferring diagrams, illustrations, and photographs into a desktop publishing program fro lay-out purposes. They can also digitize catalogs into a computer for easier storage and access. With the right software, scanners can also have optical character recognition or OCR which lets them “read” text. This process saves a lot of time and energy since a user no longer needs to type in a document he is copying. The scanner scans the document and transfers it into the computer.
The keyboard is the basic input device. Keyboards
have different kinds. There are the XT/AT, the IBM PC, and the PS/2 - enhanced
keyboards. Shown here are the parts ( and the functions) of the PS/2-enhanced