Ch. 8 – System Software and Application Software
Supplementary Notes
System Software
 Operating System (OS)
 It is responsible for the management and coordination of processes and the sharing of the
resources of the computer.
 Examples (pp.185-189):
 PC/Server: MS-DOS (Disk Operating System), FreeDOS, Windows Family
(95/98/NT/Me/2000/XP/Vista), Linux, FreeBSD, Unix, MacOS, etc.
 PDA: PalmOS, Windows Mobile, etc.
 Smartphone: Symbian OS, Andriod, PalmOS, Windows Mobile, etc.
 Basic Features (p.181)

Single-tasking VS Multi-tasking
 Single-tasking: allowing only one process to be executed at the same time. (A
process is suspended when switching to run another program)
 Multi-tasking: executing multiple tasks apparently at the same time by
time-sharing (CPU time is shared by several processes)
...
Process N
Process 3
Process 2
Process 1
...
Process N
Process 3
Process 2
Process 1
...
Process N
Process 3
Process 2
Process 1
...
...

Single-user VS Multi-user
 Single-user: being usable only by one person at a time,
 Multi-user: allowing concurrent (remote) access by multiple users.

Multi-processing
 Supporting two or more CPUs (running cooperatively at the same time)
 also called “Symmetric Multiprocessing” (SMP)
Time

Single-user, multi-tasking OS: This is the type of operating system most people
use on their desktop and laptop computers today
Ref: http://computer.howstuffworks.com/operating-system3.htm

Basic Functions (p.182)

Process Management:
 Process scheduling (arrange the priority and the order of execution)
 Controlling the execution of programs

Multi-tasking

Memory Management:
 Allocation of memory to processes
 Memory protection (one process cannot access the memory space of another)
 Paging or Swapping (of virtual memory)

File I/O and Disk Management
 Manage file read/write (e.g. arrange the sequence of read/write)
 Maintain the file system on disk (e.g. creation of folders, deletion of files)
 File protection and recovery
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Ch. 8 – System Software and Application Software
Supplementary Notes

Device I/O and Management
 Capture data input from peripherals; Manage data output to peripherals


Control the peripherals

Network Communication
 Manage communications (sending and receiving data) over network

Security:
 User right management (e.g. authentication)
 Maintain access control list for files or services
 User Interface – Allow the user to operate the computer
User Interface (p.186)
Command Line Interface (CLI)
Display text only
Operate by typing commands
User has to memorize commands
Operation is faster for experienced user
Consume less resources (CPU and RAM)
Example: DOS, Linux console

Graphical User Interface (GUI)
Graphical environments with windows, menus, icons,
scrollbars, buttons
Operate by using the pointing device (e.g. mouse)
Mouse actions: click, double-click, drag and drop
User doesn’t have to memorize command
(operation is more intuitive)
Operation is sometimes slower when both typing and
mouse actions are required
Consume more resources (especially for visual
effects, e.g. fade-in, fade-out, etc.)
Example: Windows 95 or above, Mac OS X,
X-window on Linux or Unix
Device Driver (p.179)
 Device driver, or driver program, is a computer program that allows higher-level


computer programs to interact with a hardware device. It acts as a translator,
converting general commands into specific instructions that the device understands.
To operate a hardware device, the corresponding driver program must be already
installed in the operating system. If there is no device driver installed, the device
may not operate at all.
Some device drivers are already installed in some modern OS and thus no
installation is required to operate the hardware device. E.g. mouse and keyboard.

Plug and Play (PnP) refers to the ability that the computer can detect and identify a
device, and load the corresponding device driver automatically without any manual
configuration. Note that the driver should be already installed.
Ref: http://en.wikipedia.org/wiki/Device_Driver
Ref: http://en.wikipedia.org/wiki/Plug-And-Play
 Network Operating System (NOS) (p.185)
 It is an OS built for network environment, its functions include:
 Security features: user authentication (identifying a user by username and password)
and access control (restriction of user right),
 Network resources management (e.g. managing print queue, file storage), etc.
 Examples: UNIX, Linux, Windows NT/2000/XP/Vista.
Ref: http://en.wikipedia.org/wiki/Network_Operating_System
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Ch. 8 – System Software and Application Software
Supplementary Notes
Interactions among
user, applications, OS
and Hardware:
User
Application
Application
Application
Operating System
Software
Process Management
Device I/O and Management
Memory Management
File I/O and Disk Management
Network Communication
Security
User Interface
Device drivers
Hardware
 Utility Program (pp.182-183)
 A program that performs a specific task related to the management of computer functions,
resources, or files, as password protection, memory management, virus protection, and
file compression.
 Examples: Virus scanner (Anti-virus software), disk defragmenter, disk format tool,
compression software, encryption software, backup and etc.
 Utility software has long been integrated into most major operating systems.
Ref: http://www.answers.com/topic/utility-program
Ref: http://en.wikipedia.org/wiki/Software_utility
File Attributes
 A file attribute is metadata (data that describes data) is associated with a computer file.
The
information are maintained by the OS and stored in the file system.
 File size and date/time (Creation date, Last modified date, Last access date)
 File Attributes (narrower definition, as on/off flag):
 Read-only – write protected (the file cannot be modified or deleted)
 Archive – not yet archived (backed up); set when the file has been modified
 System – system file (may be hidden from normal users)
 Hidden – the file is not shown in ordinary directory listing
 Others: Permissions (access control list), Compressed
Ref: http://en.wikipedia.org/wiki/File_attribute
Ref: http://www.xxcopy.com/xxcopy06.htm
Application Software (p.179 and Ch.3)
 An application (software) is a computer program designed to help people perform a certain type
of work (or a specific task).
 Examples:
 Word Processing Software (Word Processor), Spreadsheet Software, Presentation
Software, Database Management System (DBMS) Software (Database Software)
 Email Program, Web Browser, FTP Program
Ref: http://en.wikipedia.org/wiki/Application_software
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Ch. 8 – System Software and Application Software
Supplementary Notes
 Packaged Software VS Custom Software
 Packaged software refers to the software available in the market.

Custom software is tailor-made software providing specific functions that are not
available from any software in the market. It is developed and customized for certain
companies, organizations or government.
 It is more expensive in general; Training for users may be required.
 Examples: ATM (automatic teller machine) system, POS (point-of-sale) system,
SAMS (school administration and management system), Ticketing machine, etc.
 Installation of software
 Minimum – install the minimum set of components of the software
 Typical – install the most common components of the software
 Complete – install all components of the software
 Custom – the user can choose what components to install
 Plug-in or add-on refers to a small program that extends the capability of an application.
example, flash player plug-in for web browser.
For
Application Software and File Formats
 The OS associates file extensions with applications, and maintains the file icons. When a user
opens a file (e.g. double-click a file), the OS will launch the default application to open it.
.txt
.csv
.doc
.pdf
.jpg
Text File
Comma-separated Values
Word Document
PDF (portable document format)
Image (JPEG), or .jpeg
.exe
.ttf
.xls
.zip
.gif
Executable file
True-type Font file
Excel Spreadsheet
Compressed file (ZIP format)
Image (GIF)
.dll
.ico
.ppt
.7z
.png
Library file (system file)
Icon file
PowerPoint slideshow
Compressed file (7zip format)
Image (PNG)
.htm
HTML file (web page), or .html
.bmp
Image (Windows Bitmap)
.tif
Image (TIFF), or .tiff
.avi
.mpg
Video
Video (MPEG format)
.mov
.flv
Video (QuickTime Movie)
Flash Video
.rmvb
.3gp
Video (Real Media format)
Video (for mobile phone, etc)
Ref: http://en.wikipedia.org/wiki/List_of_file_formats_(alphabetical)
Cross Platform Issues (pp.190-191)
 The capacity of software to run on different operating systems and hardware.
Ref: http://www.wizzywigg.com/lev2_glossary.htm


Web page (and web applications)  Ch. 12 – HTML (Core Book 2, (pp.56-58)
Standardized character set  Ch. 2 – Character Coding Systems (pp.41-45)

Java – Running on Virtual Machine  Ch. 14 – Programming Languages
Software License ( Core Book 2, Ch.16, pp.158-160)
 Commercial software – user must pay to use (single-user/machine license, site license)
 Freeware – free of charge
 Shareware – demo version (function limited), trial version (time limited)
 Open source software (Free software) – free as “freedom”, free to use, modify, etc.
Source = Source code  Source code VS Executable file (or Object program/code)
 Public domain software – no owner, no copyright.
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