Comp 1001: IT & Architecture - Joe Carthy 2 Input / Output (I/O) Devices Data Automation Input Devices –OCR: Optical Character Recognition Utility Bills: ESB Typically use special font e.g. OCR1 –OMR: Optical Mark Recognition (e.g. lotto tickets) –Image scanner OCR software DIP: Document Image Processing e.g. for CAO forms –Bar code Scanner Reads an optical code Universal Product Code: UPC (supermarket checkouts/ libraries) Often used as key component of Point-of-Sale system (POS)
Comp 1001: IT & Architecture - Joe Carthy 3 Input / Output (I/O) Devices Digital Camera Voice recognition (e.g. Viva Voice by IBM, Dragon) Handwriting recognition HP Ipaq; Palm Pilot Smart Cards contain a processor e.g. Telecom phonecards MICR Magnetic ink character recognition Used on bank cheques
Comp 1001: IT & Architecture - Joe Carthy 4 Output Devices Display devices: e.g. computer monitor is what most people use with PCs. A computer terminal is made up of a monitor and a keyboard. It is a dumb device unlike a PC. Terminals may be used to access a mainframe computer. Screen size varies from 15 to 27 inches, measured diagonally across the screen. Resolution Images are usually made up of tiny “dots” called pixels (picture elements). The higher the resolution, the better the quality of picture.
Comp 1001: IT & Architecture - Joe Carthy 5 Output Devices Resolution may be measured by either –pixel density e.g..26 or.28 –(distance between pixels in millimetres) or –as a matrix of pixels e.g. 640 x 480 –640 x 480 rows VGA standard –800 x 600 SVGA standard –1024 x 768 XGA standard –1080 x 1024 SXGA standard –1600 x 1200 UXGA
Comp 1001: IT & Architecture - Joe Carthy 6 Output Devices Colour Most monitors are RGB (red-green-blue) i.e. form colours by combinations of primary colours. Most monitors produce non-interlaced images i.e all lines are redrawn when the screen is refreshed. TVs produce interlaced images i.e every other line is redrawn on every refresh. The screen is usually refreshed 60 times a second.
Comp 1001: IT & Architecture - Joe Carthy 7 Output Devices Landscape: Screen is wider than it is high Portrait: Screen is higher than it is wide CRT versus Flat-Panel Desktop monitors are typically CRT (cathode-ray tube) devices like TVs, although flat screens are becoming more popular as they take up less space but are more expensive. Notebooks use flat-screens which require less power and are lightweight. Flat-screens often use LCD (liquid crystal display) technology. Active-matrix LCDs provide sharper images than passive-matrix LCDs but at higher cost.
Comp 1001: IT & Architecture - Joe Carthy 8 Output Devices: Printers Variety of Print technologies Ink-jet: high quality and very popular: Usually Colour Laser (page printer): highest quality –Colour laser printers are much more expensive than black&white Cost of ink-jet cartridges/colour toner is an issue in choosing a printer Dot-matrix: good quality largely replaced by ink-jet Line-printers: Fast, low quality bulk printing on computer paper
Comp 1001: IT & Architecture - Joe Carthy 9 Output Devices: Others Plotters: for CAD (Computer Aided Design) output –architectural/engineering drawings –A3 laser printers now also used for these applications Speakers As in sound systems Computer Output on Microfilm (COM) e.g. for archival purposes
Comp 1001: IT & Architecture - Joe Carthy 10 Communications Devices Modem: Modulator/demodulator –Uses to allow computers communicate over analog telephone lines –Converts computer digital signals to analog signals and vice versa –Operates at speeds up to 56Kbps –bps = bits per second ISDN Card Digital communication device requires digital phone line Operates at speeds from 64Kbps, 128 Kbps (home use) to low Megabit range Much more reliable than modem DSL/ADSL Card Similar to ISDN but operates at much higher speeds (140Kbps to 3 Mbps) Network Card (Ethernet card, LAN card): Short Distances (<1000m) used inside an organisation like UCD 10Mbps to 100Mpbs to 1000 Mbps
Comp 1001: IT & Architecture - Joe Carthy 11 Computer System: Storage and I/O Devices
Comp 1001: IT & Architecture - Joe Carthy 12 I/O Devices and Communication Devices: Review Data entry –Keyboard, mouse, joystick, light pen, touch pad etc –OCR, OMR, Barcode scanner, DIP, MICR –Digital Camera, Voice, Smart Cards Output –Monitor (VGA, SVGA, XGA etc) CRT, LCD –Printer Inkjet, Laser, Dot-Matrix –Plotter –Speakers Communication Devices Modem ISDN ADSL/DSL Network Card