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Chapter 4

Information System Hardware


Our Agenda Computer Organization Input and Output Devices Primary Storage The Central Processing Unit Secondary Storage


Learning Objectives Describe the main components of

the computer. List common input and output

devices Describe how is data represented

in a computer? Describe how primary storage is

organized.


Learning Objectives (cont’d.) Describe the structure and

function of the central processing unit (CPU).

Describe how is data stored and retrieved using common forms of secondary storage?


Computer Organization



What is a computer A computer is a device that is

1. Electronic2. Can store data3. Can store and follow a set of

software instructions, called a program.


Input Devices An input device accepts data from

outside the computer and converts it into an electronic form the computer can understand.

Examples include a keyboard, mouse, scanner, digital pen, and digital tablet.


Output Devices An output device converts data

from an electronic form inside the computer to a form that can be used outside the computer.

Examples include a screen, monitor, printer, and fax.


Primary Storage Primary 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.


Central Processing Unit (CPU) The CPU, or processor, carries out

the instructions of the program. It contains circuits that perform arithmetic and logical operations.

Data is transferred from primary storage to the CPU with the results sent back to primary storage.


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 primary storage.

Examples include hard disks, floppy disks, ZIP disks, CDROMs, and DVDs.


Input and Output Devices



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.


Pointing Devices Mouse Trackball Trackpoint Trackpad, also called a touchpad Cursor


Other input devices Touch screen Pen input Graphics tablet Digitizer tablet Light pen


Optical Scanning Input Devices Bar-code scanner

Universal Product Code (UPC) Flat bed, or page scanner Automatic document feeder (ADF)

scanner Optical Character Recognition

(OCR) Mark-sense readers


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.


Voice Input Devices Voice recognition software

Dragon Naturally Speaking Via-Voice

Uses a microphone connected to the computer and translates the spoken word to text output.


Digital Input Devices Digital cameras that produce

photographic quality images. Cameras connected to the

computer for “live” images.


Screens, or 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.


Screens, or Monitor, or CRT (cont’d.) Types of monitors

Traditional “tube” monitors, or cathode 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.


Printers Printer classifications

Impact printer Nonimpact printer Serial printers Line printers Page printers Letter-quality printers Draft-quality printers


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.


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.


Other Output Devices Plotters Voice output devices – converting

digitized data into synthesized speech

Sound output devices – speakers Specialized devices for people with

disabilities – can include large typeface screens, Braille display devices, special pointing devices, or headphones.


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.

Examples include architectural design, home remodeling, aircraft design, machine design, and more.


Primary Storage



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.


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)


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 (28) binary

combinations are defined in character set.


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.


Primary Storage Structure (cont’d.) Storage locations of the “bytes” are

called allocation units each of which has a unique address.

Storage capacities Kilobyte (KB) or 1024 bytes (210) –

approximately 1,000 bytes, thus the “kilo” Megabyte (MB) or 1,048,756 bytes (220) Gigabyte (GB) or 1,073,741,824 bytes (230) Terabyte (TB) or 1,099,511,627,776 bytes

(240)


The Central Processing Unit



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.


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.


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 1,000

MHz (1 GHz).


Common CPUs Microcomputer

Intel 4004 Intel 8088 Intel 8086 Intel 80286 Intel 80386 Intel 80486 Intel Pentium Intel Pentium Pro Intel Pentium II Intel Pentium III

Apple/Macintosh Motorola 68000 Motorola 68020 Motorola 68030 Motorola 68040 Motorola Power PC G3

AMD


Common CPUs (cont’d.) Minicomputer and Mainframe

Developed by the manufacturer within a “line” of products

HP3000 IBM System/390 DEC Alpha

Supercomputers Generally specific to a single product


Secondary Storage



Types of Secondary Storage Magnetic Disk Storage

Floppy disk Hard disk ZIP disk

Disk organization Disk Head (or side) Track Allocation Unit


Optical Disk Storage Compact disks (CDROMs)

Capacity of approximately 600MB Writable Compact Disks (CD-RWs)

Capacity of approximately 600MB Digital Video Disks or Digital

Versatile Disks (DVDs) Capacity of approximately 4.7GB to

17GB depending on how it is used.


Magnetic Tape Storage Magnetic tape has a capacity of

200MB to over 40GB. Data transferred to the tape via a

magnetic tape drive. Data on a tape can only be read

sequentially.


Information Systems Hardware

Key Terms


Key Terms Address Arithmetic-Logic-Unit (ALU) ASCII Backup Copy Bar-Code Scanner Binary Digit (Bit) Byte CD-R/CD-ROM/CD-RW

Central Processing Unit (CPU) Chip Compact Disk Computer Control Unit VRT Cursor Disk Pack


Key Terms (cont’d.) Dot-Matrix Printer Draft-Quality Printer DVD/DVD-ROM EBCDIC Ergonomics Flat Panel Screen Floppy Disk Gigabyte (GB) Gigahertz (GHz)

Hard Disk Impact Printer Input Device Ink-Jet Printer Keyboard Kilobyte (KB) Laser Printer Letter-Quality Printer Line Printer


Key Terms (cont’d.) Machine Language Magnetic Disk Magnetic Disk Drive Magnetic Ink Character Recognition (MICR) Magnetic Strip Reader Magnetic Tape Magnetic Tape Drive

Massively Parallel Processing Megabyte (MB) Megahertz (MHz) Microprocessor Microsecond Millisecond Monitor Mouse


Key Terms (cont’d.) Multifunction Printer Multimedia Multiprocessing Nanosecond Nonimpact Printer Nonvolatile Storage Optical Disk Optical Disk Drive Output Device

Page Printer Parity Bit Pen Input Peripheral Equipment Pixel Plotter Primary (Internal) Storage Printer


Key Terms (cont’d.) Processor Program RAID Random Access Memory (RAM) Random (Direct) Access Read Only Memory (ROM) Scanner

Screen Screen Projector Screen Resolution Secondary (Auxiliary) Storage Sequential Access Serial Printer Storage Location Terabyte (TB)


Key Terms (cont’d.) Terminal Touch Screen Track Trackball Trackpad Trackpoint Unicode Video Display Terminal (VDT)

Virtual Reality Volatile Storage


Summary Computer Organization Input and Output Devices Primary Storage The Central Processing Unit Secondary Storage

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Documents

desiamore slide

auxiliary storage

internal storage

temporary storage

contents of primary

primary storageprimary

permanent storage

computera computer