1. PRINTERS AND OTHER DEVICES Computer Studies – Senior 3 Ms Jennifer - Senior 3 - Printers and Converters1

2. Difference between Ink jet and Laser printers Ms Jennifer - Senior 3 - Printers and Converters2

3. Difference between Ink jet and Laser printers Ink Jet ■The computer sends electrical signals to the printer’s nozzles to fire the quick dry ink onto paper. ■Ink Jet Printers use a print head with an ink chamber and rows with nozzles to spray (fire) the ink onto the paper. ■Each nozzle goes back and forth across the paper in lines while the paper moves up. Laser Printer ■The computer sends electrical signals to the laser beam. ■The laser beam fires negative charge into a metal cylinder called a drum. ■The drum rotates while it touches the toner of the printer. ■Since the toner has a positive charge and the drum has a negative charge the toner sticks to the paper. Ms Jennifer - Senior 3 - Printers and Converters3

4. Impact vs non impact Impact printersNon impact printers Ms Jennifer - Senior 3 - Printers and Converters4

5. Impact and non impact printers ■Non Impact printers do not use tiny pin heads to press on the paper. Example ink jet printers and laser printers ■Impact printers use a tiny pin head to strike the ink ribbon and press it on to the paper. These printers are noisier than non impact printers. Example: Dot Matrix printers. Ms Jennifer - Senior 3 - Printers and Converters5

6. Dot Matrix Printer Ms Jennifer - Senior 3 - Printers and Converters6

7. Dot Matrix Printer ■Dot matrix printers work by striking the pin heads onto ink than on paper. ■The printing quality depends on how many pin heads it has. ■Dot matrix printing is used for MICR (Magnetic Ink Card Reader) in Banks. To print bank receipts cheques, etc. Ms Jennifer - Senior 3 - Printers and Converters7

8. Plotter ■Plotters produce vector output graphics and are used for precision maps and designs. ■A Plotter works by making line drawings with vectors and pointers for high quality printing. ■It is also used for CAD (Computer Aided Design) for complex high quality drawings. Ms Jennifer - Senior 3 - Printers and Converters8

9. Buffers and spooling ■Buffers are physical storage devices (similar to a cache memory) which temporary store data and manage the speed and execution of programs and instructions. Therefore a buffer can slow down or speed up a process. ■Examples include a printer buffer which temporary (until instructions are executed or until the power supply is lost) stores and manages print jobs. ■The buffer acts by sorting print jobs in the buffer queue. This process is called spooling Ms Jennifer - Senior 3 - Printers and Converters9

10. COMPUTER LOGIC 1010101101 10

11. A computer understands in terms of 1’s and 0’s These 2 digits are called binary digits Each digit represents a bit Therefore one bit = one binary digit: 1 or 0 11Ms Jennifer - Senior 3 - Printers and Converters

12. How does the computer interprets the data we send to the it? Ms Jennifer - Senior 3 - Printers and Converters 12

13. We speak through the microphone (we input analogue signals) Speakers convert digital music back to the original analogue signal The microphone converts the analogue signal to digital bits of data which are transferred to the speakers 13Ms Jennifer - Senior 3 - Printers and Converters

14. 14Ms Jennifer - Senior 3 - Printers and Converters

15. Video Digitiser ■A Video Digitiser is an example of an Analogue to Digital converter which captures an analogue video still image and converts it to a digital image form. Ms Jennifer - Senior 3 - Printers and Converters15

16. DAC 16Ms Jennifer - Senior 3 - Printers and Converters

17. MIDI Instruments ■MIDI instruments are used to synthesize musical data in digital form. ■DAC – Digital to analogue converters are used to convert the MIDI music into analogue data. Ms Jennifer - Senior 3 - Printers and Converters17

18. Voice recognition systems ■Voice recognition systems measure and analyse the voice with pitch, frequencies and amplitudes and match it with a saved voice in the system. Ms Jennifer - Senior 3 - Printers and Converters18

19. 1 0 TRANSMITTER RECEIVER Ms Jennifer - Senior 3 - Printers and Converters

20. Units of Storage Ms Jennifer - Senior 3 - Printers and Converters 20

21. Task ■Give two example of midi instruments ■Give two examples of voice recorder systems Ms Jennifer - Senior 3 - Printers and Converters21