INPUT AND OUTPUT DEVICE
- 1. UNIT II INPUT AND OUTPUT DEVICES
- 2. INPUT DEVICES Keyboard A particular key is pressed, sending an electronic signal to the computers ‘brain’. The computers ‘brain’ interprets the signal. The computer sends back a particular letter or character which represents the signal that the computer has interpreted.
- 3. Mouse Controls the movement of the cursor on the screen – as you move the mouse, the cursor moves in the same direction. Useful in graphics programs where you can draw pictures by using the mouse a pen or paintbrush. So called because of it’s shape – the wire connecting it to the computer being it’s tail.
- 4. Scanner Scans a picture or text. Translates information into a form the computer can understand. This information can then be displayed on the computer screen stored to a file used in computer documents
- 5. OUTPUT DEVICES computer monitor The most obvious and useful output device, displaying text and graphics as you are working on them. Can display still or moving images. speaker: Speakers output sound from your computer. The speakers take the electronic signals stored on things like CD’s and DVD’s and send them out as the sound we can hear.
- 6. Secondary storage device Zip / Jaz Disks Similar to floppy disks • They are removable Their platters are made of a hard material • Can operate at higher speeds than floppies. Newer standards hold more data • Most people have outgrown floppy disks
- 7. Floppy Disk Floppy disks are similar to hard disks Because the medium is “floppy”, the disks cannot operate at the same speeds as a hard disk. Floppy disks are older technology which haven’t received a lot of attention since the late 1980s. Many computers today do not even come with floppy disk drives anymore.
- 8. OPTICAL DISK Optical disks are very much like hard disks. Hard disks store information using magnetic material - Bits are stored by changing the magnetic properties of the magnetic material - Bits are read by picking up the tiny magnetic field with a read head. Optical disks store information as pits in a physical medium - A laser is used to determine if a pit is present or not.
- 9. CD ROM CD Roms use the same technology as audio Compact Discs. A master disc is created. Copies of the disc are created through a pressing process The discs are aluminum sandwiched between plastic CDs are single sided.
- 10. CD-RW CD-RW is similar to CD-R The main difference is that the dye can be made reflective again through an erase process In this way, CD-RW discs can be written many times Too much erasing, and the dye starts to fade.
- 11. DVD Each side of a DVD can contain 2 layers, doubling the amount of data that can stored. One layer is semi-transparent. The laser can be focused “through” that layer onto the second layer If you took the track off of a single layer of a DVD and stretched it out into a straight line, it would be 7.5 miles long!. If you did the same with a double layer, double sided disc, the track would stretch to over 30 miles!
- 12. DVD-R and DVD-RW These two technologies are still relatively new and still fairly DVD-R and DVD-RW use similar techniques as CD-R and CD-RW A dye layer is used for data writing The dye layer in DVD-RW is erasable