Transcript Document

Think about your computer
applications
– Surfing the web
– Creating reports
– Analyzing data
– Storing information
– Making presentation
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Think about behind your computer
Loading and running programs
Coordinating networks
Organizing files
Protecting from virus
Performing periodic maintenance
Controlling hardware devices
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Think about “what if”s
New application programs can not run on
current system
Get a computer virus
Hard disk fails
A new video camera can not store and edit
image on our computer
Start and run slower and slower
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Software
Software, also called a program, is a series of
instructions that tells the computer what to do and
how to do it.
 Two general categories :
1.
System Software (Operating System)
a set of programs that interacts directly with hardware
(eg: Windows)
2.
Application Software:
programs such as Word, Excel and Access
these use OS for disk read/writes, display on screen etc.
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Categories of Software
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System Software
Difference between system software and
application software
3 basic functions of any operating system
3 categories of operating system
Purpose of utilities and utility suites
5 most essential utilities
Define device drivers
Language translators
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System Software
Handle the majority of technical details
– Where to store in memory
– How commands convert
– Where a document or file is saved
– How the output is printed
Consist of 4 kinds of programs
– Operating systems
– Utilities
– Device drivers
– Language translators
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System Software
1.1 BIOS (basic input/output system)
Is stored in the ROM chip
Contains the computer's startup instructions
1.2 Operating System (OS)
A series of programs to perform certain functions.
Low level functions loaded on boot-up:
read/write disks
allocate memory to programs
network communications
input/output support (eg:device drivers)
system security
Higher level functions usually separate programs (utilities):
provide initial user interface
Disk/file management
Monitor system performance
editor
Network administration
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Operating systems
Every computer has an operating system
3 basic functions of operating system
– Managing resources
• Keyboard, mouse, printer, monitor, storage
devices, memory
– Providing a user interface
• GUI: graphical user interface
– Running applications
• Multitasking: run more than one application
at a time
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System Software
User interface
Manage programs
Start the computer
Manage memory
Manage
security
Administer
security
Control network
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Monitor performance
Access the web
Schedule jobs and
configure devices
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System Software
Starting up an OS is called BOOTING-UP
Steps in booting up:
•Turn on the computer. Power supply sends electrical signals to all parts
of the computer.
•The processor chip looks for the BIOS in the ROM chip.
•BIOS executes POST (power on self test), checks components eg
keyboard, drives etc.
•POST results are compared to data in CMOS chip.
•BIOS searches for system files from A: drive , then from C: drive.
•System files are loaded in memory. (RAM)
•Finally, the OS is loaded into memory. (RAM)
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System Software
1.3 Categories of OS
• users/tasks
(a) A single user/single tasking operating
system
OS allows only one user to run one
program at a time eg: DOS
(b) A single user/multitasking operating
system.
CPU allows a single user to work on two or more
programs that reside in memory at the same time.
Eg. Windows 3.X, windows 95/98
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Categories of OS
• users/tasks
(c) A multi-user operating system
supports two or more simultaneous users.
All mainframes and minicomputers are multi-user systems, but
most personal computers and workstations are not.
Another term for multi-user is time sharing.
Eg. Unix, Linux (multitasking)
(d) A multiprocessing operating system
CPU’ssupports two or more Central Processing Units
(CPUs) running programs at the same time within a
single computer system
Eg. Win NT/2000/XP, Unix, Linux
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Categories of OS
• stand-alone/network/embedded
(a) stand-alone
•works on a desktop computer, notebook computer, or
mobile computing device.
•Some are called client operating systems because they
also work in conjunction with a network operating
system.
•Client operating systems can operate with or without
a network.
•Eg. DOS, Windows XP, Mac OS X, OS/2 Warp Client,
UNIX, and Linux.
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Categories of OS
(b) Network (NOS)
is designed specifically to control a network
and its message (e.g. packet) traffic and
queues, controls access by multiple users
to network resources.
Eg. NetWare, Windows Server 2003, OS/2
Warp Server for e-business, UNIX, Linux,
and Solaris.
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Categories of OS
(c) Embedded
is an operating system for embedded computer
systems.
designed to be very compact and efficient,
forsaking many functions that non-embedded
computer operating systems provide, and which
may not be used by the specialized applications
they run.
They are frequently also real-time operating
systems.
on most PDAs and small devices
reside on a ROM chip.
e.g. Windows CE .NET; Pocket PC 2002, Palm OS,
and Symbian OS.
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Operating Systems
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Operating Systems
Windows XP
Mac OS X
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System Software
1.4 Features of an OS
(a) multi-user
(b) Virtual Memory Management
RAM can seemingly be expanded by using some of
a hard disk to act as extra 'main memory
(c) Scheduling jobs
•OS determines the order in which jobs are done.
•Not always first in first done.
•Some jobs have higher priority.
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Virtual Memory Maps to Physical Memory
To facilitate
copying virtual
memory into
real memory,
the operating
system divides
virtual memory
into pages, each
of which
contains a fixed
number of
addresses
The copying of virtual pages from disk to main
memory is known as paging or swapping
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System Software
1.5 Command Based vs Graphical
 Unusable if do not know commands
eg. copy A:afile.doc C:\bak\newname.doc
 Graphical presents commands via pull-down menus
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Utility Programs
• Type of system software that allows a user
to perform maintenance-type tasks
usually related to managing a computer,
its devices, or its programs
Programs that make computing easier
– Hard disks can crash
– Virus can invade a system
– Computers can freeze up
– Operations can slow down
Five most essential utilities
– Troubleshooting programs
– Antivirus programs
– Uninstall programs
– Backup programs
– File compression programs
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Windows Utilities
Start->All programs->accessories->system tools
Backup
– Protect from hard disk failure
Disk cleanup
– A trouble-shooting utility
– Identifies and eliminates nonessential files
– Frees up valuable disk space
– Improves system performance
Disk defragmenter
– Eliminates unnecessary fragments
– Rearranges files and unused disk space
Disk Scanner
– detects and corrects both physical and logical problems
– searches for and removes unnecessary files
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Utility Suites
• Combine several programs
into one package
(1)Personal Computer Maintenance
(2)Antivirus programs
(3)File Compression
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Utility Suites
2 best known utility suites
– McAfee Office
– Norton System works
• A suite of five separate program groups
• Each can be purchased separately or as
part of the suite
– Norton Utilities
– Norton AntiVirus
– Norton CleanSweep
– Norton CrashGuard
– Norton Web Services
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Device Drivers
Specialized programs that allow devices to
communicate with the rest of the computer
system
When computer started, the OS loads all of the
device drivers into memory
A new device added, its driver must be installed
before it can be used
– From windows
– From product’s manufacturer
Install drivers in Windows OS
– Control panel-Add/Remove Hardware
Wizard
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Programming Languages
•a vocabulary and set of grammatical rules for
instructing a computer to perform specific tasks.
•Each language has a unique set of keywords and a
special syntax for organizing program instructions.
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Programming Languages
Languages improved in
parallel with hardware
developments.
1st. Generation
· Machine language
· Written in the language of
the computer – 0’s and 1’s
· The language to which all
other generations of languages
must be converted.
Each different type of CPU
has its own unique machine
language
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Programming Languages
2nd. Generation
· Assembly language
· Used simple abbreviations or
codes to represent a number of
machine language instructions
· Codes converted to machine
language by a special program
called an assembler.
Eg. SUB STA LDA
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Programming Languages
3rd. Generation
· High level languages
· More English like
· Single command generates 100s of machine language instructions
· Allow concentration on logic of solving problem rather than
controlling computer
· Compiler program converts instructions into machine language,
stored as an EXEcutable file.
Eg. BASIC, COBOL, C
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Programming Languages
4th. Generation
· Very high-level languages
· Non-procedural. Programmer tells computer what to do
but not how to do it.
· Programmer can be 10 times more productive than in 3rd
generation language.
· Eg. databse query language (SQL, dBase, Prolog)
LIST name FOR town=”Bendigo”
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Programming Languages
5th. Generation
Provides a visual or
graphical interface
for creating source
code.
Use of Natural
language
Visual basic is an
example
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Which is the best?
• The question of which language is best is one
that consumes a lot of time and energy among
computer professionals.
• Every language has its strengths and weaknesses.
– FORTRAN is a particularly good language for
processing numerical data, but it does not
lend itself very well to organizing large
programs.
– Pascal is very good for writing wellstructured and readable programs, but it is
not as flexible as the C programming
language.
– C++ embodies powerful object-oriented
features, but it is complex and difficult to
learn.
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Language Translators
Computers only understand machine language
consisting of 0’s and 1’s
– Tedious, difficult
Programming language more closely to human
language were developed
Language translator
– convert programming statements into zeros
and ones
– Make computer be able to process
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Application Software
2. Application Software
• performs some specific application required by the user
• current program and data stored in RAM
• RAM memory for program allocated by OS
• Program stores data within its allocation
2 types ...
1. Specialist
eg.
Information Systems
ECNU Student Records
2. General
eg.
Word
Access
Excel
Games
CAD
Programming Language
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Exercise
Finish Tutorial 3: Secondary Storage
Save the answer in StuIDNameT3.doc
Prepare for Tutorial 4: Operating System
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