Introduction to Computing: Lecture 3 Computer Systems

2 Overview This Lecture covers:  To learn to classify computers according to their capability and targeted applications.  To find out about the essential building blocks that make up a modern computer.

3 Computer Hardware The physical parts of a computer are collectively known as hardware. Internal hardware is located within the main box (system unit) of the computer. External hardware is located outside the system unit and plug into connectors called ports located on the exterior of the system unit.

4 Hardware Components Essential hardware components are:-  Input unit  Output unit  Storage unit  Memory unit  Processing unit

5 Input Devices the devices through which a user instructs a computer about what to do. In other words, a unit which is used for getting data or instructions into the system.

6 Common Input Devices

7 Categories of Input Devices

8 Input Devices for Information and Commands Keyboards – most frequently input devices for notebooks and desktops to enter information and commands. Stylus – most frequently used input devices for PDAs and tablet PCs to enter information and commands.

9 Input Devices for Commands Pointing Device – used to input commands:  Mouse – device you use to click on icons and buttons.  Trackball – similar to a mechanical mouse, but with the ball on top.

10 Input Devices for Commands  Touchpad – dark rectangle you use to move the cursor with your finger.  Pointing stick – a little rod, used mostly on notebooks.

11 Game Controllers Game controller – used for gaming to control screen action.  Gaming wheel – steering wheel and foot pedals for virtual driving.  Joystick – controls action with a vertical handle and programmable buttons.  Gamepad – device with programmable buttons, thumb sticks, and a directional pad.

12 Scanners Scanners – used to convert information that exists in visible form into electronic form:  Image scanner – captures images, photos, text, and artwork.  Bar code scanner – reads information in the form of vertical bars.  Optical mark reader – detects the presence or absence of a mark.  Optical character reader – reads characters that appear on paper or sales tag.  Biometric scanner – scans a human physical attribute, like a fingerprint or iris, for security purposes.

13 Digital Cameras Digital camera – captures still image or video as a series of 1s and 0s.  Digital still camera – digitally captures still images in varying resolutions.  Digital video camera – captures video digitally.  Webcam – captures digital video for the Web.

14 Output Devices The devices that communicate the results of a computation to the user. In other words, the devices which give the results to the users.

15 Categories of Output Devices

16 Monitors

17 Monitors CRT – monitors that look like traditional TV sets. Flat-panel display – thin, lightweight monitors that take up much less space than CRTs. Two types of flat-panel displays:  Liquid crystal display (LCD) monitor – sends electricity through crystallized liquid between layers of glass or plastic.  Gas plasma display – sends electricity through gas trapped between layers of glass or plastic.

18 Printers

19 Printers Resolution of a printer – the number of dots per square inch (dpi) it produces. Types:  Inkjet printer – makes images by forcing ink through nozzles.  Laser printer – forms images using the same electrostatic process that photocopiers use.  Multifunction printer – scan, copy, and fax, as well as print.

20 Storage Devices Where information that is required to be used much later is stored. In other words, where the data is stored on permanent basis.

21 Categories of Storage Devices

22 Capacity of Storage Devices Megabyte (MB or M or Meg) – about 1 million bytes. Gigabyte (GB or Gig) – about 1 billion bytes. Terabyte (TB) – about 1 trillion bytes.

23 Magnetic Storage Devices and Media

24 Magnetic Storage Media Hard disk – magnetic storage with one or more thin metal platters sealed inside the drive. Zip disk – high capacity (100 MB, 250 MB, and 750 MB) removable storage medium. Floppy disk – removable storage medium that holds 1.44 MB.

25 Optical Storage Media

26 Optical (or Laser) Storage Media Optical storage media – plastic discs on which information is stored, deleted, and changed using laser technology. Two types:  CDs  DVDs

27 Compact Disks CD-ROM (compact disc read-only memory) – information cannot be changed. CD-R (compact disc – recordable) – write one time only. CD-RW (compact disc – rewritable) – save, change, and delete files repeatedly.

28 DVDs DVD-ROM – high capacity; information cannot be changed. DVD-R or DVD+R (DVD – recordable) – high capacity; write one time only. DVD-RW or DVD+R (depending on manufacturer) – save, change, delete repeatedly.

29 Flash Memory Devices and Cards Flash memory device – very small storage device that plugs into USB port. Flash memory card – high capacity storage laminated inside a small piece of plastic.

30 Common Types of Flash Memory

31 Summary The categories of computers on the basis of their size & capability. Input units of computer system. Output units of computer system. And storage units of computer systems.