Transcript Introduction to IT Hardware

Introduction to IT Hardware
• Hardware: the collection of digital devices used to input,
store, process and output data
• Choice of hardware affects choices of all other IT
components and operation of entire system
• Central processing unit (CPU):
– composed of arithmetic/logic unit (ALU), control unit, registers
– associated with short-term data storage
– is basis on which hardware is configured
• CPU is linked to
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Input devices
Communications devices
Output devices
Secondary storage
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Evaluating CPUs and Memory
• CPUs are evaluated using the concepts of machine cycle time,
clock speed, and wordlength and bus line width
• Machine cycle time:
– length of time required to execute single instruction
– Expressed as microseconds (time) or millions of instructions per second
(MIPS; rate)
• Clock speed:
– rate at which the CPU produces electronic pulses
– based on execution of elementary instructions
– Expressed as millions of cycles per second (Megaherz; MHz)
• Wordlength and bus line width
– wordlength is number of bits CPU can process at once
– bus line width is amount of bits that can be transferred among
components
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Comparing CPUs
• CPU measures of machine cycle time, clock speed and
wordlength/bus line width cannot be directly compared
• Clock speed along is insufficient for good comparisons
• Intel Corporation has introduced Intel Comparitive
Microprocessor Performance Index, or iCOMP
– iCOMP weights values of various measures
– is used for for comparing Intel processors, not systems; system
performance affects CPU performance
• CPU empirical principles
– All else equal, more clock speed is preferable to less
– CPU speed always increases due to increase in transistor densities
(Moore’s Law)
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Memory Characteristics
• Memory associated with CPU measured in thousands, millions,
etc. of bytes (KB, MB…) of storage capacity
• Memory types:
– volatile random access memory (RAM), data that disappears when the
system is powered down
– non-volatile read-only memory (ROM), providing permanent storage for
data and instructions that do not change over time
– Cache memory, high-speed memory providing access to frequently used
data
• Secondary storage represents permanent storage of greater
volumes of data than available in main storage:
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Magnetic tapes
Magnetic disks (incl. RAID)
Optical disks
Digital video disk (DVD)
Removable storage
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Input Devices
• Input devices provide data and instructions to the computer.
• Management issues associated with input devices include:
– is input data human-readable, or machine-readable, or both?
– Can data entry and data input be done on-line and instantly?
– Can input data be modified?
• Types of input devices include:
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keyboard and mouse
voice-recognition devices
digital computer cameras
terminals
scanning devices
optical data readers
magnetic ink character recognition (MICR) devices
automatic teller machine (ATM) devices
bar code scanners
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Output Devices
• Output devices are intended to provide information to decisionmakers or to other information systems
• Types of output devices:
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cathode-ray tube (CRT) display monitor
liquid-crystal display (LCD) display monitors
printers and plotters
computer output microfilm (COM) devices
speakers
multifunction devices
Choosing the right mix of input and output devices can mean the
difference between an IS that is implemented successfully or not
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Computer Systems
• Computer systems are the collection of CPU type, memory,
input and output devices
• Computer systems can be classified in the following way:
istic
Network
Computer
1-5 MIPs
Personal
Computer
5-20 MIPs
RAM
4-16 MB
e
eed
50-100 MIPs
Midrange
Computer
25-100 MIPs
Mainframe
Computer
40-4,550
MIPs
16-128 MB
32-256 MB
32-512 MB
$500-$1,500
$1,200 $5,000
$4,000 to over
$20,000
Simple data
entry
Improve
individual
productivity
Engineering,
CAD,
software
development
$20,000 to
over
$100,000
Computing
needs for
department
or small
company
256-1,024
MB
$250,000 to
over $2
million
Computing
needs for a
company
Oracle
Network
computer
Compaq
Pentium
Computer
Sun
Microsystems
computer
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Workstation
HewlettPackard HP9000
MIS 90-728 Lecture Notes
IBM ES/9000
Supercomputer
60 billion – 3
trillion
instructions
per second
8192 MB+
$2.5 million $3.5 million
Scientific
applications,
customer
support
product
development
Cray C90
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Introduction to IT Software
• Computer software (programs) provide sequences of
instructions to control operations of computer hardware:
– Software can comprise 75% or more of the total cost of an IS
– Expense of software due to developer salaries, increasingly complex
requirements and reductions of hardware costs
• Computer software can be divided into two categories:
– systems software, which coordinates activities of hardware and various
programs. Combination of systems software and hardware configuration
is called the computer system platform
– application software, which help users solve particular computing
problems of importance to individual, group or enterprise.
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Management Issues in Software Use
• One way to classify software is by the portion of the
organization affected by use of the software, or sphere of
influence
– personal: software addresses needs of individual user
– workgroup: two or more people who work together to achieve common
goal
– enterprise: firm or company
• Use of software had brought about issues that previously were
addressed in an organization-by-organization basis:
– software licensing: copyright protection and patent laws
– software upgrades: purchase/no purchase decision, distributing changes
– software support: outsourcing, free vs. pay, medium by which help
delivered
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Systems Software
• Operating systems typically execute a variety or tasks:
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Providing common computer hardware functions
Providing a user interface
Managing system memory
Controlling access to system resources
• Operating systems act as a buffer between application programs
and computer hardware
• Common features of operating systems:
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graphical user interface
hardware independence
multitasking/multithreading
time-sharing
scalability
networking capability
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Popular Operating Systems
• MS-DOS
– single-user, single-task system
– requires specialized knowledge of command syntax
– limited memory management
• DOS with Windows
– actually a shell that sits atop MS-DOS
– graphical user interface, some multitasking capabilities
– developed in response to Apple Macintosh OS
• OS/2
– true multitasking/multithreading capability
– significant memory requirements
– lack of consumer applications written for OS/2
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Popular Operating Systems (cont’d)
• Windows 95
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true 32-bit, multitasking, multithreading OS
vulnerable to “misbehaving” 16-bit applications
uses desktop metaphor
solidified Microsoft position as pre-eminent supplier of PC OS
• Mac OS 8.1
– Intended to run on Motorola PowerPC processors
– dominant in education, publishing and graphic arts
– supports novice through expert user with variable user environment
• Windows NT 5.0
– designed to run on multiple hardware platforms
– centralized security system
– represents strategic direction of all Microsoft OSs
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Popular Operating Systems (cont’d)
• Unix
– OS of choice for large database applications and application servers
– Arcane, text-based user interface supplanted by Motif/X-Windows GUI
– platform independent
• What OS is right for your organization? Try to account for:
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OS market share
networking capabilities
type of application programs used
ease of use
OS management requirements
• Utility programs are used to enable an OS to run more
efficiently and safely:
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anti-virus protection
diagnosing hardware problems
security management
automated data backup
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Application Software
• Application software are programs that help individuals,
workgroups and organizations become more productive and
meet organization goals
• Types of application software:
Pros
Cons
– proprietary
– off-the-shelf
• Personal application software:
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word processing
spreadsheet analysis
databases
graphics programs
on-line information services
software suites
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Workgroup/Enterprise Application Software
• Groupware is software that enables persons to work more
efficiently together
• Types of groupware:
– Lotus Notes
– Group scheduling/project management
• Three C’s of groupware: convenient, content, coverage
• Enterprise application software address problems common to a
whole organization:
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accounts receivable
general ledger
shipping
payroll
enterprise resource planning
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Software Development
• Programming languages are coding schemes that provide
instructions to the computer system to perform a processing
activity
• Programming languages have evolved over time:
– First-generation languages: machine languages
– Second-generation languages: assembly language
– Third-generation languages: use of symbolic code, hardwareindependent (Cobol, C, Pascal, Basic)
– Fourth-generation languages: more visual, less procedural, focus on
intended outputs (Access, Visual Basic, SQL)
– Object-oriented languages: tie data and procedures into objects, enable
reusability and modularity (Smalltalk, C++, Java)
– Fifth-generation languages: visual programming, reuse management to
enable knowledge-based applications (Java Studio/Java Beans)
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The Internet
• The Internet is a worldwide collection of interconnected
networks; estimated 200,000 networks and 100 million
computers
• The Internet works by transmitting data from one computer (a
host) to another using:
– the Internet Protocol (IP) and Transport Control Protocol (TCP)
– Uniform Resource Locater (URL)
• Host URLs follow this convention:
– Foreign hosts end URL with country abbreviation
– U.S. hosts end URL with affiliation ID, e.g. .arts, .com, .mil, .org
• The Internet can be accessed by:
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LAN server
SLIP/PPP
On-line service
Internet service provider
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Internet Services
• E-mail: send messages to remote users incorporting sound,
graphics, hyperlinks as well as plain text
• Telnet and FTP: log in to remote computers to transfer files
• Usenet and Newsgroups: follow threaded discussions stored on
host computers on a variety of subjects
• Internet Phone/Videoconferencing: route phone calls and faxes
over same network used to transfer data, bypassing phone
company
• Content streaming: method to transfer multimedia files over the
Internet so that voice and pictures are aligned
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The World Wide Web
• Originally conceived as a document management system, has
evolved to thousands of Web servers that allow access to
specialized documents that store text, data, images and sound
• A Web site is a collection of files designed to allow the user
access to various files (Web pages) in a predefined order
• A Web browser is an application that translates specialized
commands (HTML) with which Web pages are created into a
graphical interface
• Search engines are tools that allow users to quickly scan the
internet for Web pages that satisfy certain criteria
• Java is a programming language that enables applications
residing on a Web page to be run on the user’s computer
The Web is revolutionizing many business, non-profit and
personal activities by enabling universal connectivity
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