1 California State University, Fullerton Chapter 4 Information System Hardware

2 California State University, Fullerton What is a computer A computer is a device that is 1.Electronic 2.Can store data 3.Can store and follow a set of software instructions, called a program.

3 California State University, Fullerton Input Devices An input device accepts data from outside the computer and converts it into an electronic form the computer can understand. Keyboard Pointing devices Scanner Touch screen Light pen/electronical pen/stylus (pen like instrument) Pen commuter (these input devices use pen technology) Digitizer (digitizing) tablet/graphics tablet (this instrument is used in computer aided design/CAD) Personal digital assistant (PDA)

4 California State University, Fullerton Output Devices An output device converts data from an electronic form inside the computer to a form that can be used outside the computer. Monitor (is a device that produces on screen text, graphics, & images) Printer (is an instrument that produces on paper text & graphics, & images) Plotter (is an instrument that produces on paper high quality graphic output)

5 California State University, Fullerton Primary Storage Primary storage, read and write storage, also called internal storage, is the “memory”, or RAM, of the computer. Primary storage, which is temporary storage, is dependent upon continuous electrical power. Any interruption of electrical power causes the contents of primary storage to be lost.

6 California State University, Fullerton Central Processing Unit (CPU) The CPU, or processor, carries out the instructions of the program. It contains circuits that control the operations of the hardware an the circuitry that performs arithmetic and logical operations. Data is transferred from primary storage to the CPU with the results sent back to primary storage.

7 California State University, Fullerton Secondary Storage Secondary storage, also called auxiliary storage, stores data not currently being processed by the computer and represents permanent storage. Data is usually transferred to and from Secondary storage. Examples include hard disks, floppy disks, ZIP disks, CDROMs, and DVDs.

8 California State University, Fullerton Keyboards Most widely used input device. Possible physical problems include Repetitive strain injuries Carpal tunnel syndrome Ergonomically designed keyboards may improve user comfort and efficiency and reduce risk of injury.

9 California State University, Fullerton Pointing Devices Mouse Trackball Track point/pointing stick Track pad/touch pad Cursor (is an on screen symbol that shows the current position of the pointing device)

10 California State University, Fullerton Other input devices Touch screen Light pen/electronic pen that are used with Graphics tablet/Digitizer tablet

11 California State University, Fullerton Optical Scanning Input Devices Bar-code scanner Universal Product Code (UPC) Flat bed, or page scanner Automatic document feeder (ADF) scanner Mark-sense readers

12 California State University, Fullerton Magnetic Scanning Input Devices Magnetic strip reader Credit cards ID Cards Magnetic Ink Character Recognition (MICR) – used at the bottom of all checks by the banking industry.

13 California State University, Fullerton Voice Input Devices Uses a microphone connected to the computer and translates the spoken word to digital input.

14 California State University, Fullerton Video Input Devices Digital cameras that converts photographic images in to digital format.

15 California State University, Fullerton Screens, Monitor, or CRT Key elements of a “screen” include: Pixels – picture elements arranged as a pattern of dots. Screen resolution – the number of pixels that can be displayed on a screen at one time. Refresh rate – the number of times per second that screen “repaints” itself.

16 California State University, Fullerton Screens, or Monitor, or CRT (cont’d.) Types of monitors Traditional “tube” monitors, or cathode (electronic gun) ray tube (CRT). Flat-panel screens – most common type is liquid crystal display (LCD). Screen projector used to display a computers output on a large screen.

17 California State University, Fullerton Printers Printer classifications Impact printer Nonimpact printer Serial printers Line printers Page printers Letter-quality printers Draft-quality printers

18 California State University, Fullerton Desktop printers Ink-jet, or bubble-jet printer Typically 200 to 300 characters per second Laser printers Typically between 4 and 24 pages per minute. Dot matrix printer Typically between 200 and 300 characters per second.

19 California State University, Fullerton High volume printers Line printers High end line printers can print as much as 3,600 lines per minute (at 60 lines per page, that is 60 page per minute) and can cost $50,000. Page printers High end page printers can print as much as 200 pages per minute and can cost $100,000.

20 California State University, Fullerton Other Output Devices Plotters Voice output devices – converting digitized data into synthesized speech Specialized devices for people with disabilities – can include large typeface screens, Braille display devices.

21 California State University, Fullerton Virtual Reality Virtual reality is the use of a computer to produce realistic images and sounds in such a way that the user senses that he or she is a part of the scene. Applications include architectural design, home remodeling, aircraft design, machine design, and more.

22 California State University, Fullerton Primary Storage Structure Input data is stored in primary storage (memory) after it is received from an input device. Output data is stored in primary storage before it is sent to an output device. Without sufficient primary storage, it may not be possible to execute certain programs or use certain data.

23 California State University, Fullerton Primary Storage Structure (cont’d.) Silicon chips – integrated circuits Volatile storage – dependent upon continuous power Random Access Memory (RAM) Non-volatile storage Read-Only Memory (ROM)

24 California State University, Fullerton Primary Storage Structure (cont’d.) Binary representation A combination of positive and negative electrical charges, represented by 1s and 0s when written to represent a character. One “charge” is called a bit. Eight bits are required to represent a single character, called a byte. The 256 possible (2 8 ) binary combinations are defined in character set.

25 California State University, Fullerton Primary Storage Structure (cont’d.) Personal computer character set ASCII – American Standard Code for Information Interchange Mainframe computer character set EBCDIC – Extended Binary Coded Decimal Interchange Code Though each contains 256 characters, the definitions are not the same, so a “translator” is required for one machine type to “talk” with the other machine type.

26 California State University, Fullerton Primary Storage Structure (cont’d.) Storage capacities Kilobyte (KB) or 1024 bytes (2 10 ) – approximately 1,000 bytes, thus the “kilo” Megabyte (MB) or 1,048,756 bytes (2 20 ) Gigabyte (GB) or 1,073,741,824 bytes (2 30 ) Terabyte (TB) or 1,099,511,627,776 bytes (2 40 )

27 California State University, Fullerton Two Main Parts of a CPU Arithmetic-Logic Unit (ALU) May add, subtract, multiply and divide two numbers. More complex operations are are completed by using sequences of the four basic operations. Control Unit Analyzes and executes instructions in a program. Instructions are brought in one at a time from primary storage.

28 California State University, Fullerton CPU Speed Early CPUs processed 8 or 16 bits at a time. Current CPUs process 32 bits, and some can process 64 or 128 bits at a time. The “roadway” from primary storage to the CPU is the bus. Higher bus capacities mean faster computers.

29 California State University, Fullerton CPU Speed (cont’d.) Clock speed Measured in megahertz (MHz) or gigahertz (GHz). One MHz is one million cycles per second. One GHz is one billion cycles per second. Earliest IBM PCs ran at 4.77 MHz. Current PCs run at or above 2,000 MHz (2 GHz).

30 California State University, Fullerton Types of Secondary Storage Magnetic Disk Storage Floppy disk Hard disk ZIP disk Disk organization Disk Head (or side) Track Cylinder

31 California State University, Fullerton Optical Disk Storage Compact disks (CDROMs) Writable Compact Disks (CD-RWs) Digital Video Disks or Digital Versatile Disks (DVDs)

32 California State University, Fullerton Magnetic Tape Storage Data transferred to the tape via a magnetic tape drive. Data on a tape can only be read sequentially.