Operate Computer Hardware

Peripherals

• The term peripherals refers to all hardware devices that are attached to your computer and are controlled by your computer system
• Peripherals can be classified into input devices and output devices.
• Some can be both an input device and an output device

Input Devices

• An input device is a piece of equipment that enables data to be entered into a computer for example:

• Keyboard
• Mouse
• Joystick

• Graphics Tablet
• Digital Camera
• Scanner

Keyboards

• The keyboard is made up of push-button switches which send a signal to the CPU each time you press them.
• Keyboard standards vary with names like Deluxe, Natural and Cordless.

Mouse

• A roller mouse has a ball that is rolled as the mouse is moved about on the desktop.
• Pointing and clicking allows operations to be performed without having to remember complicated keyboard commands.
• Optical mice are superseding ball mice and use a light instead of a ball.

Digital Cameras

• Allow us to capture images and transfer them to a computer in the form of an image file.
• Image quality is measured in pixels.
• Some digital cameras can capture small amounts of video.

Scanners

• Scanners allow us to capture an image or text and convert it into digital form.
• Optical Character Recognition (OCR) software converts the picture of the scanned text into true text that can be processed further in an application such as Word.

Output Devices

• Output devices allow information to output from a computer.
• Examples of output devices are:

• Monitors
• Printers

• Projectors
• Plotters

Monitors

• The monitor or visual display unit (VDU) is the most significant output device.
• Desktop displays use a cathode ray tube (CRT)
• Laptops incorporate liquid crystal display (LCD)
• Plasma

Monitors

• Standard desktop monitors are Super VGA
• Screen sizes vary from 14” to the larger plasmas found on high end graphics workstations

Resolution

• Refers to the number of individual dots of color, known as pixels, contained on a display.
• Is expressed by the number of pixels on the horizontal axis (rows) and on the vertical axis (columns), such as 1024x768.
• Monitors normally support resolutions matching the physical pixel grid as well as the resolution capability of your video card.

Dot Pitch

• Is the measure of how much space there is between a display’s pixels, the smaller the dot pitch the better quality image displayed.
• .22 mm
• .25 mm
• .26 mm
• .28 mm

Refresh Rate

• Refresh rate is the number of times that the screen image is updated per second.
• If your monitor has a refresh rate of 75 Hertz (Hz), then it cycles through all the pixels from top to bottom 75 times per second.
• Too few cycles per second will cause flickering which can lead to headaches and eye strain.

Color Depth

• The combination of the display modes supported by your monitor and graphics adapter determine how many colors can be displayed.
• Color capability is expressed as a BIT DEPTH.
• The bit depth determines the number of colors that can be displayed at one time.

Color Depth Chart

Bit-depth	Number of colors
1	2	Monochrome
2	4	CGA
4	16	EGA
8	256	VGA
16	65,536	High color, XGA
24	16,777,216	True color, SVGA
32	16,777,216	True color + Alpha Channel

Printers

• The types printer include:
• Laser – Expensive, used mostly in medium to large organisations
• Ink Jet – Typically found in small business and SOHO
• Dot Matrix – Found mostly in large organisations for printing process reports and large volumes of data

Printers

• Speed – measured in Pages Per Minute (PPM)
• Quality – measured in Dots Per Inch (DPI)
• The higher the DPI the better the print quality

Peripherals

• Prepared by Karimov Bunyod
• Group 654-18