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Transcript of chap 4 MIS
8/11/2019 chap 4 MIS
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Computer Hardware
History of computers
Types of computer systems
Hardware components and functions
Computer peripherals
a p
er 4
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Learning Objectives
1. Understand the history and evolution of computerhardware.
2. Identify the major types and uses of
microcomputer, midrange and mainframecomputer systems.
3. Outline the major technologies and uses ofcomputer peripherals for input, output, and
storage.4. Identify and give example of the components and
functions of a computer system.
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Learning Objectives
5. Identify the computer systems and peripherals youwould acquire or recommend for a business of yourchoice, and explain the reasons for your selections.
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Calculating pre-computer
Counting on fingers and toes
Abacus: manipulating stones or beads to count
The word calculate comes from calculus, the Latin
word for small stoneFirst mechanical adding machine
Invented by Blaise Pascal in 1642
Wheels to move counters
Machines in the age of industrialization
Mechanical loom with cards punched with holes
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Early computing
Charles Babbage and the Analytical Engine
19th century
Machine that calculated, stored values in memory and
perform logical comparisons Mechanical rather than electronics
Herman Hollerith and the 1890 census
Punched cards to record census data
Cards read in a tabulating machine
Hollerith’s company went onto become IBM
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Electronic computers
ENIAC – first electronic and digital computer
1946
Programmable
5000 calculations per second Used vacuum tubes
First generation computer
Drawbacks: size and could only do one program at atime
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Next wave of computing
Second generation, late 1950s
Transistors replace the vacuum tubes
200,000 to 250,000 calculations per second
Third generation, mid 1960s Integrated circuitry, miniaturization
Fourth generation, 1971
Further miniaturization of circuits Multiprogramming and virtual storage
Fifth generation, 1980s
Millions of calculations per second
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Microcomputers
1975, ALTAIR, flicking switches
1977, Commodore and Radio Shack producepersonal computers
1979, Apple computer, the fastest selling PC so far1982, IBM introduces the PC which changes the
market
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Computer System Categories
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Microcomputer Systems
Personal Computer (PC) – microcomputer for use byan individual
Desktop – fit on an office deskLaptop – small, portable PC
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Microcomputer Systems
Workstation – a powerful, networked PC for businessprofessionals
Network Server – more powerful microcomputers thatcoordinate telecommunications and resource sharing in small
networks
Networks of microcomputers are replacing mainframes
Sometimes called workstations
Used for CAD, CAE, complex simulations and scientificapplications
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How corporate buyers choose PCs
Solid performance at a reasonable price
Operating system ready
Connectivity – reliable network interface or wireless
capability
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Information Appliances
Hand-held microcomputer devices
Personal digital assistants (PDA)
BlackBerry
Video-game consoles Internet enabled cellular phones
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Midrange systems
High-end network servers
Minicomputers for scientific research and industrialprocess monitoring
Less costly to buy, operate and maintain thanmainframe
Often used as the host computer in a network ofsmaller computers
Priced in the several thousands to a few hundredthousand dollars
Manufacturers: DEC (VAX), IBM (AS/400), andHewlett-Packard
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Mainframe Computer Systems
Large, fast powerful computer systems
Large primary storage capacity
High transaction processing
Complex computations
Less powerful and less expensive thansupercomputers
Used by businesses with large amounts of datathat need to be stored in a central computer
Can be used as superservers for large companies
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Supercomputer Systems
Extremely powerful systems
Scientific, engineering and business applications atextremely high speeds
Global weather forecasting, military defenseParallel processing with thousands of
microprocessors
Billions of operations per second
Millions of dollars and Used by universities,research institutions, and large corporationsMinisupercomputers costing hundreds of thousands
of dollars
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Computer hardware functions
Input Keyboards, mice, optical scanners
Convert data into electronic form
Processing Central Processing Unit (CPU)
Arithmetic-logic unit performs the arithmetic functions
Control unit
Output Video display units, printers, etc.
Convert electronic information into human-intelligibleform
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Computer hardware functions
Storage
Primary Storage Unit or memory
Secondary Storage
Magnetic disks and Optical disksControl
Control unit of the CPU
Controls the other components of the computer
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Computer Processing Speeds
Millisecond – thousandth of a second
Microsecond – millionth of a second
Nanosecond – billionth of a second
Picosecond – trillionth of a second
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Computer Processing Speeds
MIPS – million instructions per second
Teraflops – trillions of floating point operations persecond (Supercomputer)
Clock speed of the computer: Megahertz (MHz) – millions of cycles per second
Gigahertz (GHz) – billions of cycles per second
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Moore’s Law
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Technology of self-service kiosks
Networked special-purpose microcomputerterminals
Video touch screens
Built-in thermal printers Magnetic-stripe card reader
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Peripherals
Peripheral is generic name for all input, output, andsecondary storage devices that are part of thecomputer system but are not part of the CPU
Online devices Separate from CPU
But electronically connected to and controlled by CPU
Offline devices
Separate from and not under control of the CPU
Peripherals are online devices
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Peripheral Checklist
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Input technologies
Keyboard: most widely-used
Graphical user interface (GUI)
Icons, menus, windows, buttons, bars
Used for selection
C I t D i
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Common Input Devices
Keyboard
Pointing Devices
Pen Based Computing
Speech RecognitionOptical Scanning
Magnetic Ink CharacterRecognition
Smart Cards
Digital Cameras
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Pointing Devices
Electronic Mouse
Trackball – Stationary devicelike a mouse
Roller ball used to movecursor on screen.
Pointing Stick – Small eraserhead-like device in keypad
Moves cursor in direction ofpressure placed on stick.
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Pointing Devices
Touchpad – Small rectangular touch-sensitive surface
Moves the cursor in the direction of finger moves onthe pad
Touch Screen – use computer by touching screen Video display screen that emits a grid of infrared
beams, sound waves, or a slight electric current
Grid is broken when the screen is touched.
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Pen-based Computing
Used in Tablet PCs and PDAs
Pressure-sensitive layer like touch screen underliquid crystal display screen
Have software that digitizes handwriting, handprinting, and hand drawing
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Speech Recognition Systems
Discrete: pause between each word
Continuous: conversationally-paced speech
System compares your speech patterns to library ofsound patterns
Training: to recognize your voice patterns
Speaker independent system: understand voice never
heard before Used in voice-messaging computers
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Optical Scanning
Read text or graphics and convert them into digitalinput
Desktop or flatbed scanners
Optical Character Recognition (OCR): Read characters and codes
Used to read merchandise tags, sort mail, score tests
Optical scanning wands
Read bar codes such as the Universal Product Code(UPC)
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Other Input Technologies
Magnetic stripe
Read magnetic stripe on credit cards
Smart cards
Microprocessor chip and memory on credit card Used more often in Europe than in US
Digital cameras
Magnetic Ink Character Recognition (MICR)
Identification numbers of bank and account printed inmagnetic ink on bottom of check
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Output Technologies
Video displays Cathode ray tube (CRT) like a television
Most desktop PC screens
Liquid crystal displays (LCDs) Laptop and PDAs, some PCs
Printed Output Inkjet printer
Spray ink on page
Laser printer Electrostatic process like photocopying machine
Voice response systems
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Storage tradeoffs
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Computer Storage Fundamentals
Binary representation
Data are processed and stored in computer systemthrough the presence or absence of signals
Either ON or OFF
ON = number 1
OFF = number 0
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Th Bi S t U i O /Off El t i l St t
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The Binary System: Using On/Off Electrical Statesto Represent Data & Instructions
Kilobyte 1000 bytes
Megabyte 1,000,000 bytes (one million)
Gigabyte 1,000,000,000 bytes (one billion)
Terabyte 1 trillion bytes
Petabyte 1 quadrillion bytes
The Binary System: Using On/Off Electrical States
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The Binary System: Using On/Off Electrical Statesto Represent Data & Instructions
lASCII - the binary codemost widely used withmicrocomputers
lEBCDIC - used with largecomputers
lUnicode - uses two bytes foreach character rather than
one
The Parity Bit
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The Parity Bit
lEven parity - sum ofbits must come out
even
lOdd parity - sum ofbits must come out
odd
Even parity scheme
Parity bit - an extra bit attached to the end of a byte for purposes
of checking for accuracy
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Machine Language
Machine language -a binary-typeprogramming
language that thecomputer can rundirectly
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i d i l
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Direct and sequential access
S i d t
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Semiconductor memory
Microelectronic semiconductor memory chips
Used for primary storage
Advantage:
Small size Fast
Shock and temperature resistance
Disadvantage:
Volatility: must have uninterrupted electric power orlose memory
Two types of semiconductor
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Two types of semiconductor
memory
RAM: random access memory Most widely used primary storage medium
Volatile memory
Read/write memoryROM: read only memory
Permanent storage
Can be read but cannot be overwritten
Frequently used programs burnt into chips duringmanufacturing
Called firmware
M ti T
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Magnetic Tape
Secondary storage
Tape reels and cartridges
Used in robotic automated drive assemblies
Archival storage and backup storage
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T f ti di k
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Types of magnetic disks
Floppy disks Magnetic disk inside a plastic jacket
Hard disk drives
Magnetic disk, access arms, and read/write heads insealed module
RAID (Redundant arrays of independent disks)
Disk arrays of interconnected hard disk drives
Fault tolerant with multiple copies on several disks
Fl Di k
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Floppy Disks
Floppy disk - a removable flatpiece of mylar plastic packaged
in a 3.5-inch plastic case
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Flash drive
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Flash drive
New type of permanentstorage
Uses semiconductor memory
Small chip with thousands of
transistors Easily transported
Also called jump drives, USBflash drives
Source: Courtesy of Lexar Media.
Hard Disks
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Hard Disks
Hard disks - thin but rigidmetal platters covered with asubstance that allows data tobe held in the form ofmagnetized spots
Hard Disks
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Hard Disks
Head crash - event that happens when the surface of theread/write head or particles on its surface come into contactwith the surface of the hard-disk platter, causing the loss ofsome or all of the data on the disk
Hard Disks
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Hard Disks
Nonremovable hard disks - housed in a microcomputer systemunit and used to store nearly all programs and most data files
Hard Disks
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Hard Disks
Removable hard disks - oneor two platters enclosed alongwith read/write heads in ahard plastic case, which isinserted into amicrocomputer’s cartridgedrive
Bits on disk - dark stripes are 0
bits and bright stripes are 1 bits
Optical Disks
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Optical Disks
Optical Disks: CDs & DVDs
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Optical Disks: CDs & DVDs
Optical disk - a removable disk on which data is written andread through the use of laser beams
Uses of optical disks
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Uses of optical disks
Image processing Long term storage of historical files of images
Scan documents and store on optical disks
Publishing medium for fast access to referencematerials
Catalogs, directories, etc.
Interactive multimedia applications
Video games, educational videos, etc.
Radio Frequency Identification
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Radio Frequency Identification
RFIDTag and identify mobile objects
E.g., store merchandise, postal packages, pets
Use RFID chips to transmit and receive radio signalsChips half the size of a grain of sand
Passive chips:
do not have power source and derive power from
signal in reader
Active chips:
Self-powered
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Summary
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Summary
Computer components and their functions
Computer communication
Categories of computers have different strengths andweaknesses
Understand commonly used hardware terminology
Identify and evaluate key criteria for purchasing decisions