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Software: System Software

Williams, B.K, Stacy C. Sawyer (2007). Using Information Technology: A Practical Introduction to Computers & Communications. Seventh Edition, McGraw-Hill, New York. ISBN-13: 978-0-07-110768-6

Sumber: Chapter 3. Software: Tools for Productivity and Creativity, p.117

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Learning Outcomes

Pada akhir pertemuan ini, diharapkan mahasiswa

akan mampu :

• menjelaskan: pengertian dan komponen system software, dan fungsi-fungsi sistem operasi

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Outline Materi

• System Software: The Power behind the Power

• The Operating System: What It Does

• Other System Software: Device Drivers & Utilities

• Common Features of the User Interface

• Common Operating Systems

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System Software: The Power behind the Power

• Application Software– Software developed to solve a particular problem for

users• Either performs useful work on a specific task • Or provides entertainment

– We interact mainly with this software

• System Software– Enables application software to interact with the

computer– Helps the computer to manage its own internal and

external resources

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System Software: The Power behind the Power

• System Software has 3 basic components– Operating System (OS)

• The principal component of system software• Low-level, master system of programs to manage basic

computer operations• Some hardware requires specific Operating Systems

– Macintosh computers run Macintosh OS – PCs run Microsoft Windows, Linux, or BSD

– Device Drivers• Help the computer control peripheral devices

– Utility Programs• Used to support, enhance, or expand existing programs in

the computer

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The Operating System: What It Does

• Booting– The process of loading an OS into the computer’s

main memory– The steps are:

1. Turn the computer on2. Diagnostic routines test main memory, CPU, and other

hardware3. Basic Input/Output System (BIOS) programs are

copied to main memory– BIOS contains instructions for operating the hardware– The computer needs those instructions to operate the hardware

and find a copy of the OS

4. Boot program obtains the OS and loads it into computer’s main memory

The Operating System: What It Does

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• Central Processing Unit (CPU) Management– Kernel is the supervising software that manages CPU

• Kernel must remain in memory while the computer runs• If another program uses the kernel’s memory when the

kernel needs it, the computer will crash– Memory Management

• OS keeps track of memory locations to prevent programs and data from overlapping each other

• Swaps portions of programs and data into the same memory but at different times

• Keeps track of virtual memory– Queues, Buffers, Spooling

The Operating System: What It Does

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• Central Processing Unit (CPU) Management (continued)

– Queues, Buffers, Spooling• Queue: First-in, First-out (FIFO) sequence of data or

programs that waits in line for its turn to be processed• Buffer: The place where the data or programs sit while they

are waiting• To Spool: The act of placing a print job into a buffer

– Needed because the CPU is faster than printers– The CPU can work on other tasks while the print jobs

wait

The Operating System: What It Does

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• File Management– A file is either a

• Data File: a named collection of data

• Program File: a program that exists in a computer’s secondary storage

– The File System arranges files in a hierarchical manner

• Top level is Directories (aka Folders)

• Subdirectories come below Folders

– Find files using their pathname

• C:/MyDocuments/Termpaper/section1.doc

The Operating System: What It Does

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• Task Management– Required for computers that accommodate multiple users– Required for computers that allow multiple simultaneous

applications – Methods of processing two or more programs

MultitaskingBy one user on one processor

Time-sharingBy multiple users in round-robin fashion on one processor

MultiprogrammingBy multiple users concurrently on one processor

MultiprocessingBy one or more users simultaneously on two or more processors

The Operating System: What It Does

The Operating System: What It Does

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• Security Management– Operating Systems permit users to control

access to their computers– Users gain access using an ID and password– You set the password the first time you boot

up a new computer– System Administrators can set up new

accounts and assign new passwords

The Operating System: What It Does

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Other System Software: Device Drivers & Utilities

• Device Drivers– Specialized software programs that allow input and

output devices to communicate with the rest of the OS– When you get a brand-new printer or monitor, you may

also need to install the device driver for it– Device drivers come with new hardware, or download

from the manufacturer’s website, or sites like www.driverguide.com or www.windrivers.com

• Utilities– Service programs that perform tasks related to the

control and allocation of computer resources– Some come with the OS, others can be bought

separately like

• Norton SystemWorks, McAfee Utilities

Other System Software: Device Drivers & Utilities

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• Practical Utility programs perform the following tasks– Virus protection– Data compression– File defragmentation– Disk scanner & disk cleanup– Backup– Data recovery

Discussion Question: How many of you have lost important files such as a term paper? Didn’t you wish you had made a backup copy? ALL data media are subject to possible failure and data loss!

Other System Software: Device Drivers & Utilities

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Common Features of the User Interface

• User Interface– The user-controllable display screen you use to

interact with the computer

• Keyboard and Mouse– User input devices that you use to interact with the

display screen– Both devices have special-purpose keys

• Keyboard Special-purpose keys: Esc, Ctrl, Alt, Del, Ins, Home, End, PgUp, PgDn, Num Lock

• Mouse special-purpose keys: left-click, right-click, and (on some mice) scroll wheel or center click

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• Keyboard– Function Keys – let you quickly perform specific tasks– Escape Key – lets you quit a task– Ctrl and Alt – use combination with another key to bypass using the

mouse – Ctrl + S will save a document, Alt + Tab will let you switch between running applications

Common Features of the User Interface

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• Keyboard continued– Application key – quickly displays the shortcut

menu for any item on your screen– Status lights – indicate if your Num Lock or

Caps Lock keys are on – Numeric Keypad – allows you to type in

numbers when the Num Lock light is on

Common Features of the User Interface

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• Mouse– Handy tool

for dragging and dropping text, graphics

– Useful for navigating menus on unfamiliar applications

Common Features of the User Interface

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• Graphical User Interface (GUI)– Allows you to use a mouse or keystrokes to select

icons and commands from menus– Replaces command-driven interfaces used in earlier

programs– Three main features are: desktop, icons, and menus

• Desktop: The system’s main interface screen• Icon: Small pictorial figure that represents a program, data

file, or procedure – Rollover: A small text box that explains the icon when

you roll your mouse over it• Menus: A list of built-in commands and/or options from which

to choose

Common Features of the User Interface

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• To start an application, pick one of 3 methods:– Click on the Start button on the lower left corner of the Windows

desktop– Click on the My Computer icon on the desktop, find the

application executable on your hard disk, and click it– Click on the My Documents icon on the desktop, find the

document you want to open, and click it. It should automatically open the application that created it, if you have that application installed

Common Features of the User Interface

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• Most Operating Systems have the following:– Title Bar: runs across the top of the display window– Menu Bar: shows the names of the pull-down menus available– Toolbar: Displays menus and icons representing the most-

frequently used commands– Taskbar: The bar across the bottom of the Windows screen that

contains the Start button– A window: A rectangular frame on the computer screen through

which you can view a file of data or an application

Common Features of the User Interface

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Common Operating Systems

• Platform– The particular processor model and operating system on which

a computer system is based

• Operating Systems are platform-specific• PC (Wintel) platforms

– Dell, Compaq, Hewlett-Packard, IBM PCs– Originally ran Disk Operating System (DOS)– Currently run Linux, Unix, Windows

• Apple (Macintosh) platforms– Run Mac OS (System 9 was proprietary, OS X is Unix-based)

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• Mac OS– The OS that runs on Apple Macintosh computers– Pioneered the easy-to-use GUI– Proprietary OS

• System 9 is OS from 1999, but still popular• Mac OS X is based on BSD Unix kernel• Tiger is 2005 release of Mac OS X; features include

– Spotlight – a desktop search engine for locating files on local hard disk

– Dashboard – for creating desktop “widgets”– Automator – automatically helps users to script repetitive

tasks

Common Operating Systems

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• Unix, Solaris, BSD– Developed at AT&T Bell Laboratories in 1969 as

minicomputer operating system– Is a multitasking operating system with multiple users

that has built-in networking capability and a version for every platform

– Unix interface• GUI – An optional shell program that starts after the kernel• Command interface – starts when kernel loads

Common Operating Systems

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• Linux– A flavor (version) of Unix– A free, nonproprietary version of UNIX

• May legally be downloaded and used for free• May legally be modified for free, as long as modifications

aren’t copyrighted• In 2000, adopted by China as national standard OS

– Linux vendors produce Linux Distributions• Software is distributed for free• Support services are sold for a profit

– Many PCs are set up to dual-boot Linux and Windows

Common Operating Systems

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• Operating Systems for Handhelds– Palm OS

• Dominant handheld OS• Proprietary OS requires proprietary software

– Windows CE• Has familiar Windows look and feel• Can be directly programmed using Visual Basic 2005

– Symbian OS• Symbian is world’s largest producer of smartphone software• Software is open-source

Common Operating Systems