Ch 2 - Computer Systems

Report
MANAGING INFORMATION TECHNOLOGY
7th EDITION
CHAPTER 2
COMPUTER SYSTEMS
-HARDWARE
-SOFTWARE
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2-1
HARDWARE
Building Blocks of Information Technology
Hardware
Chapter 2
Software
Chapter 2
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Networks
Chapter 3
Data
Chapter 4
2-2
COMPUTER SYSTEMS
• Hardware:
Physical pieces of a computer system
• Software:
Set of programs that control the operations of a computer
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BASIC COMPONENTS OF COMPUTER SYSTEMS
• All computers made up of the
same set of six building blocks:
input, output, memory,
arithmetic/logic unit, control
unit, and files
• Control unit and
arithmetic/logical unit together
known as the central processing
unit (CPU)
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BASIC COMPONENTS OF COMPUTER SYSTEMS
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Input:
• Device(s) needed to enter
data into the computer for it
to use in computations and
comparisons
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Input: What is the difference between a terminal
and a PC?
• Terminal
-
Designed strictly for input and output
Has keyboard and screen
Does not have a processor
Connected to a computer with a processor via
telecommunications
- Examples: point-of-sale terminal, ATM
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Common Input Methods:
-
Keyboard: input entered by user through keystrokes
Mouse, stylus, touchpad: alternative to keystrokes
Disk drive or flash drive: data on disk read into memory
Magnetic ink character recognition (MICR): used to process
bank checks
- Barcode labeling: scans barcodes on packages or products, and
reads into computer
- Optical character recognition (OCR): directly scans typed,
printed, or handwritten material
- Imaging: inputs digital form of documents and photos
Keyboard
Disk Drive
Barcode
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Output:
• Device(s) needed to produce
results in a usable format
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Common Output Methods:
- Video display unit: displays output on a screen
- Disk drive or flash drive: output written to disk for storage
- Printer: output to paper (various types of printers)
- Computer output microfilm (COM): microfilm generated
for archive copies in small space
- Voice response units: computer-generated verbal response
messages
Video Display
Disk Drive
Microfilm
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Memory:
• Referred to as main memory or
primary memory
• All data flows to and from
memory
• Divide into cells
- Each has a unique address
- Can only store limited amount
of data
-Byte: stores one character of data
-Word: stores two or more
characters of data
Memory
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Memory:
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Memory:
•
•
•
•
•
Each memory cell is a set of circuits
Each circuit is on or off (represented by 1 or 0)
Each circuit corresponds to a bit (binary digit)
Most computers – 8 bits (circuits) represents a character (byte)
2 common bit coding schemes used today:
- ASCII
- EBCDIC
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Arithmetic/Logical Unit:
• Carries out:
- Mathematical operations
(addition, subtraction,
multiplication, division)
- Logical operations
(number comparisons)
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Arithmetic/Logical Unit:
• Consists of VLSI circuits on a silicon chip
• Can perform up to billions of operations per second
• Numbers are taken from memory as input and results are
stored in memory as output
ALU Circuits
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Computer files:
• File devices used to store vast
quantities of data
• Main memory is limited,
volatile and expensive
• Advantages:
- File devices or secondary memory
are used to store additional data that
is non-volatile
• Disadvantages:
- It has relatively slow speed
• Storage Devices:
-
Magnetic tape drives, disk drives,
floppy drives
Optical CD or DVD drives
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Types of Computer files:
• Sequential Access Files
- Records are stored in sequence according to file’s control
key
- Usually stored on magnetic tape
• Direct Access Files
- Records can be accessed immediately, without regard to
physical location
- Stored on Direct Access Storage Devices (DASD)
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DIRECT ACCESS STORAGE DEVICES
• Types of DASD:
• Fixed (hard) drives
• Optical disk storage
- CD-ROM
- CD-R
- CD-RW
- DVD-ROM
- DVD-R
- DVD-RW
• Removable drives
- Floppy Drives
- Zip Drives
- Flash (keychain) Drives
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Control unit:
• Controls the other five
components of the computer
system
• Used to take advantage of speed
and capacity of other
components
• List of operations, called a
program, tells the control unit
what to do
• These operations are read from
memory, interpreted, and
carried out one at a time
(stored- program concept)
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STORED-PROGRAM CONCEPT
• Computer Program
- A list of what is to be done for an application
- Each step or operation is called an instruction
• Machine Language
- Computer program written for specific computer model
- Program executed by control unit; consists of operation code and
addresses
• Measure of Computer Power
- Millions of instructions per second (MIPS)
- Millions of floating point operations per second (MFLOPS)
• Benchmarking is used to compare speed for running a set of jobs on
different machines
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TYPES OF COMPUTER SYSTEMS
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Table 2.1
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TYPES OF COMPUTER SYSTEMS
Microcomputers:
• For personal computing
• Can generally be carried or moved by one person and only
have one keyboard and display unit
• Examples:
- Desktop PC
- Laptop or notebook
- Handheld or personal digital assistant (PDA)
- Tablet PC
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TYPES OF COMPUTER SYSTEMS
Microcomputers:
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TYPES OF COMPUTER SYSTEMS
Microcomputers, continued:
• Two major microcomputer platforms
- IBM-compatible PCs (personal computers)
- Apple microcomputers (does not use Windows OS)
• Have been put to a myriad of uses
- Record-keeping
- Word processing
- Presentations
- Programming
- and a “client” in a client/server system
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TYPES OF COMPUTER SYSTEMS
Midrange systems:
• In 1980s, included 2 types of computer systems
1. Workstations
- Microcomputers with more powerful chips than PCs
- Reduced instruction set computing (RISC) chip yielded
greater performance because it was specialized
2. Minicomputers
- Less powerful and less expensive than mainframe systems
- Used for departmental computers & office automation
Midrange Systems
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TYPES OF COMPUTER SYSTEMS
Midrange systems - today:
• Servers for client/server applications, Web server, etc.
- Low-end
- Essentially high-powered PCs
- Typically built on Intel Pentium, Celeron, Xeon or AMD
processors
- Often run Windows Server software
- High-end
- Powered by RISC processors or top-of-the-line Intel or
AMD processors
- Usually run Linux or some variation of UNIX
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TYPES OF COMPUTER SYSTEMS
Mainframe Computers:
• Computer platforms for most major corporations and
government agencies
• Major strength is versatility in application processing
- Online and batch processing
- Integrated enterprise systems
- Engineering and scientific applications
- Network control
- Systems development environment (not production)
- Web server
• Major players today: IBM, Fujitsu, Unisys
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TYPES OF COMPUTER SYSTEMS
Supercomputers:
• “Number-crunchers” at 250K MFLOPS
• Handle problems generated by research scientists
• High-end supercomputers located in government, R&D labs,
major universities
• Cost: $1 - $100 million
• One of fastest supercomputers (IBM Blue Gene/P):
294,912 processors and can achieve speed of 1 petaflop
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SOFTWARE
Building Blocks of Information Technology
Hardware
Chapter 2
Software
Network
Chapter 2
Chapter 3
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Data
Chapter 4
2-29
TWO CATEGORIES OF SOFTWARE
1. Applications software
2. Support software
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APPLICATIONS SOFTWARE
• Programs written to accomplish particular business tasks:
accounting, payroll, inventory, sales invoicing, etc.
• Programs that users interact with
• Software for standard applications typically purchased from a
vendor
• Software for applications unique to the organization typically
developed internally or via a vendor contract
• Includes personal productivity software by knowledge workers
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APPLICATIONS SOFTWARE EXAMPLE
• Accounting Software Package:
- Commercial accounting package for smaller businesses
- Includes general ledger, accounts receivable, accounts
payable, inventory, payroll, time and billing, job costing,
fixed asset accounting, and analysis and reporting tools
- Price: $500 for single-user version
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APPLICATIONS SOFTWARE EXAMPLE
Personal Productivity Software
may be purchased as a software suite
- Word Processing
- Spreadsheets
- Database Management Systems
- Presentation Graphics
- Electronic Mail and Groupware
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APPLICATIONS SOFTWARE
Personal Productivity Software
• Database management systems
- Used to create, manage and protect organizational data
- All employ a relational data model
• Database
- Is a shared collection of logically related data organized to
meet organizational needs
- MS Office Example : Access
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APPLICATIONS SOFTWARE
Personal Productivity Software
• Presentation graphics
- Used to create slide shows for business presentations
- All allow embedding of clip art, photos, graphs, and other
media
- MS Office Example: PowerPoint
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APPLICATIONS SOFTWARE
Personal Productivity Software
• Electronic mail
• Groupware
- Incorporates e-mail and other productivity features, such as
calendaring, scheduling, and document sharing
- MSOffice Example : Outlook
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APPLICATIONS SOFTWARE
WWW Browsers
• Used to access information (navigate) on the WWW from
computers that can access the Internet
- Hypertext-based approach (to link text and media objects to
each other)
• Pull technology: browser requests a Web page before it is
sent to client
• Push technology: data sent to client without requesting it
(such as e-mail, spam, software patches)
• Examples:
Internet Explorer (Microsoft), Firefox (Mozilla), Safari (Apple)
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SUPPORT SOFTWARE
• Enables applications software to be carried out (run)
• Ensures that computer hardware and software are used efficiently
• Purchased from a hardware or software vendor
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SUPPORT SOFTWARE
Operating System (OS)
• Usually purchased from manufacturer of computer hardware
that OS will be used on
• Complex program that controls operation of computer
hardware and coordinates other software
• Performance objective is to maximize work done (throughput)
• User communicates with operating system software for input,
output, storage, etc.
• Easier to use with graphical user interface (GUI): click on
icons instead of enter text commands
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SUPPORT SOFTWARE
Operating System
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SUPPORT SOFTWARE
Operating System Concepts
•
Job control language (JCL): instructions used to communicate with the
operating system
•
Multiprogramming: employed on larger machines to overlap input and output
operations with processing time, keeping the CPU busy and speeding up
execution
•
Multitasking: similar to multiprogramming, but employed on microcomputers
•
Multithreading: similar to multitasking, but multiple threads within the same
program are overlapped
•
Multiprocessing: work that takes place when two or more CPUs are installed
on same computer system
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SUPPORT SOFTWARE
Operating System Concepts, cont.
• Virtual Memory:
- Optimizes management of main memory by switching in
and out portions of programs from DASD
-- Permits multiprogramming to operate more efficiently
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SUPPORT SOFTWARE
Operating System Concepts, cont.
- Proprietary systems: operating systems written for a
particular computer hardware configuration
- Microcomputers: MS-DOS, Vista, Windows 7, Mac OS
- Large systems: IBM z/OS and z/VM
- Open systems: not tied to any particular computer system or
hardware manufacturer – will run on virtually any computer
• Examples: UNIX and Linux
- IT Platform: set of hardware, software, communications ;
OS name usually implies platform
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SUPPORT SOFTWARE
Server or Network Operating System (NOS)
- Software running on a server that manages network
resources and controls the operation of a network
- Enhanced operating system that allows for:
- Sharing disk drives and printers
- Handling server side of client/server applications
- Major players include:
- UNIX and Linux
- Microsoft Windows Server
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SUPPORT SOFTWARE
First and Second Generation Languages
• Machine language (1GL)
• Each instruction must be expressed in unique form for a
particular computer
• Complete program consists of thousands of instructions
• Programming is a tedious, time-consuming process
• Assembly languages (2GL)
• Easily remembered mnemonic operation codes substituted for
machine language operation codes
• Assembler used to convert mnemonic codes to machine
language
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SUPPORT SOFTWARE
First and Second Generation Languages
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SUPPORT SOFTWARE
Third Generation Languages
• Procedural languages (3GL)
- Express a step-by-step procedure devised by the
programmer
- Typically machine independent
- Easier for programmers to learn
- Structured programs: divided into modules, where each has
one entry and one exit point
- Must be compiled or interpreted (translated into machine
language) ; one 3GL instruction typically translates into
many machine language instructions
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SUPPORT SOFTWARE
Compiling and running a 3 GL Program
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SUPPORT SOFTWARE
Developing programs with a 3GL
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SUPPORT SOFTWARE
Third Generation Languages
• Most popular procedural languages & decade introduced
1950s - FORTRAN
1960s - COBOL (COmmon Business Oriented Language)
BASIC
1970s – C
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SUPPORT SOFTWARE
COBOL program example
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SUPPORT SOFTWARE
Fourth Generation Languages
• Nonprocedural languages (4GL)
• Easier to program, but less efficient for computers to run
• Uses more English-like statements for program instructions
• Today may be referred to as a language for business
intelligence (BI) application development
•
•
•
•
•
SAS
IBM Cognos
SAP Business Objects
Oracle BI Enterprise Editing Plus
Microsoft SQL 2008 Services (Analysis, Reporting)
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SUPPORT SOFTWARE
Markup Languages
• Employ tags to “mark up” documents
• HTML
- Used to create Web pages
- Consists of special tags that tell the Web browser how to display
various elements on a Web page (e.g., bold-faced or italic text,
image location, links to other Web pages)
HTML Example
• XML
- Used to facilitate data interchange among Web applications and
Web services
- Meta language consisting of tags that identify particular data
elements
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EXAMPLES
XML Example (tags in brackets)
<Game type= “College Football” date=“9/26/2009”>
Indiana vs. Michigan
<Score team= “Indiana”>33</Score>
<Score team= “Michigan”>36</Score>
</Game>
XML Example
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SUPPORT SOFTWARE
Object-Oriented Programming (OOP) Languages
• Neither 3GL nor 4GL … new paradigm
• Create objects once, store, then reuse
• Object examples:
- Text box, check box
• Most Common Languages:
- C++, Java, Visual Basic.NET, C#
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SUPPORT SOFTWARE
Object-Oriented Programming – Java Example
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SUPPORT SOFTWARE
Languages for Developing Web Applications
• HTML is the most common form of user interface
• Server-side programming languages include:
• PHP
• Java Servlets and Java Server Pages (JSP)
• Microsoft’s Active Server Pages (ASP, ASP.NET)
• Adobe’s ColdFusion
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SUPPORT SOFTWARE
Database Management Systems (DBMS)
- Systems that create, store, and manage modifications to data
in a database – and make data accessible for queries, reporting
Data Dictionary/Directory
- Repository for data definitions used by a Database
Data Warehouse
- Very large database or collection of databases for decision
support that use a DBMS optimized for analytics (including
data mining)
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SUPPORT SOFTWARE
5 DBMS Architectures
1.
Hierarchical
• Data are arranged like a top-down organization chart
• Example: IBM Information Management System (IMS)
2.
Network
• Data are arranged like cities on a highway system, often with
several paths from one piece of data to another
• Example: Computer Associates’ CA-IDMS
3.
Relational
Most common type
Data arranged in simple tables
Records related by storing common data in each associated
table
Examples: Microsoft Access and SQL Server, Paradox,
DB2, and Ingres
•
•
•
•
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SUPPORT SOFTWARE
DBMS Architectures
4. Object- Oriented
• Data can be graphics, video, and sound as well as simpler
data types
• Attributes and methods are encapsulated in object classes,
and relationships between classes can be shown by nesting
one class within another
• Examples: Versant Object Database, Progress ObjectStore,
and Objectivity/DB
5. Object-relational
• Hybrid approach that can handle complex data types with the
simplicity of the relational model
• Examples: Oracle, IBM’s DB2 and Cloudscape, and FFE
Software’s First SQL/J
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SUPPORT SOFTWARE
• Query Language example: SQL/DS Command Language
SELECT ORDER#, CUSTOMER#, CUSTNAME,
ORDER-DATE FROM CUSTOMER, ORDER
WHERE ORDER-DATE> ‘03/12/11’
AND CUSTOMER.CUSTOMER# =
ORDER.CUSTOMER#
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SUPPORT SOFTWARE
Computer-aided software engineering (CASE) Tools
• Collection of software tools to help automate all phases of the
software development life cycle to increase productivity of
software designers and programmers
• CASE tools for OO development for Unified Modeling
Language ( UML)
- UML = general-purpose notational language for
specifying and visualizing complex software, especially
large, object-oriented projects
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SUPPORT SOFTWARE
Communications Interface Software
• For Large computers:
• Controls communications between workstations and
terminals connected to a network & central computer
• Example: IBM’s Customer Information Control System
(CICS)
• Web Server Software serves Web pages to Web browser
• File Transfer Protocol (FTP) transfers files from one computer
system to another
• Utility programs: link together programs & subprograms,
merge files (ZIP programs), check for viruses, etc.
FTP
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KEY SOFTWARE TRENDS
• More concern with human efficiency
• More purchased applications software
• More open source support software
• More programming using object-oriented languages
• More emphasis on applications that run on intranets and the Internet
• More user development
• More use of personal productivity software on microcomputers
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IT INDUSTRY TRENDS
Hardware firms
• Have been expanding by adding services (including acquiring
established consulting firms)
• Major players:
- US: IBM, Hewlett-Packard, Dell , Apple
- Non US : Acer, Lenovo, Toshiba, Fujitsu, Sony
Software firms
• Have been expanding by developing new products and acquiring
smaller software companies
- IBM bought Cognos; SAP bought Business Objects
- Oracle bought PeopleSoft and Salesforce.com
- Oracle also bought Sun (hardware and Java)
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COPYRIGHT
All rights reserved. No part of this publication may be reproduced, stored in a retrieval
system, or transmitted, in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without the prior written permission of the
publisher. Printed in the United States of America.
Copyright © 2012 Pearson Education, Inc.
Publishing as Prentice Hall
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