Peripherals

1. 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

2. 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

3. 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.

4. 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.

5. 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.

6. 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.

7. Output Devices • Output devices allow information to output from a computer. • Examples of output devices are: • Projectors • Plotters • Monitors • Printers

8. 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

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

10. 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.

11. 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

12. 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.

13. 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.

14. Color Depth Chart

15. 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

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