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

http://www.unicode.org/

http://www.unicode.org/

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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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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

http://www.pctechguide.com/04disks.htm

http://www.pctechguide.com/04disks.htm

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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

Documents

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