Transcript Software

Fundamentals of Hardware and
Software
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Distinguish between systems
programs and application programs
System software - This software is usually called
an operating system since it controls the
hardware and how all the other software work.
The most commonly used operating system is
Windows made by Microsoft Corporation.
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Operating System
• This is the most important system software; it
manages the operations of the CPU, controls
the input, output, and storage resources, and
controls computer tasks.
• E.g. Windows, Mac OS (Macintosh), UNIX,
Linux
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Utility Programs -are used for routine, repetitive
tasks; they are common to all computer system
software.
• e.g Desktop utilities- are available from the taskbar, computer
directory, and recycle bin;
• The menu bar and toolbar-provide utilities to manage files and folders
and for customizing the desktop and windows.
• Disk formatting-removes information from the disk and prepares it for
the operating system.
• Disk defragmentation -increase the speed of access and retrieval from a
disk by rewriting parts of a file to contiguous sectors on a disk.
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Language Translators are system programs
that translate a program’s language into
machine language so that it can be processed.
• A compiler is a translator that changes the
programming code into machine code.
• An interpreter is a special compiler that
translates and executes each program statement
one at a time
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Application software
This software instructs a computer to carry out or
perform a specific task. Word Processors,
Spreadsheet and databases are all
application software.
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• General purpose software - Programmes
which are designed to cover a single but broad
application scope. Prime examples of this are
programmes such as
• Microsoft Word,
• spreadsheet operations
• database management.
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Advantages
Many persons use it.
Help is readily available.
Updates are readily available.
Cheaper than custom written software
• Disadvantage
• Does not meet the specific needs of the
individual.
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Custom-written software
• Programs which have been created specifically
to meet the needs of a particular individual or
company. It is very similar to you going to a
tailor for him to make a suit to meet your
fashion needs.
• Macros are usually added to general purpose
software
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Advantages
1. You get exactly what you want.
2. Your software runs faster since the code is
optimized to serve your specific purposes only.
3. You are in more control of revisions made to
the software.
Disadvantage
1. Its development is time consuming.
2. Its development is very costly to the individual
or company.
3. Special training is necessary which can also be
expensive and time consuming
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Customization of general-purpose
software
• Imagine having an article of clothing which does
not quite suit you. You would take this garment
to the tailor and ask him to modify it to suit you.
Customisation of general-purpose software is
just like this.
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• Advantages
• Meets the specific needs of the user
• More cost effective than designing customwritten software
• Disadvantages
• Updates will not be as easily obtainable as with
the general- purpose software.
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Integrated Software
A collection of computer programs designed to
work together to handle an application, either
by passing data from one program to another or
as components of a single system, such as,
word processing, spread sheets, data-base
management, graphics, and data
communications.
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Specialized software packages
• These are programs designed to give the user
a range of different tools for assistance in
completing a specific or narrow kind of task,
rather than for a broad application area. An
example of this could be a program especially
designed for preparing and printing DVD labels.
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• Advantages
• Makes work easier and more efficient for its
users.
• Disadvantage
• Does not meet the general needs of end users.
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Operating System Components
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Process management
Main memory management
File management
I/O management
Device Management
Security
User Interface
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Major Benefits of an OS
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Convenience: facilitates the use of hardware
Efficiency: ensures that resources are used efficiently
Security: ensures that resources are not misused
Communication: enables access to other computers
Real-Time Support: enables real-time constraints to be met.
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Process Management
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A process is a running program
A process runs sequentially
A process requires access to system resources
A process may need to communicate with other
processes.
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Main Memory Management
• Main memory is the work space for the CPU
• – Consists of a large array of words
• – Each word is addressed by its index in the
array
• The code and data of an executing process
must be resident in main memory
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File Management
• A file is an abstract, uniform unit of stored
information
• – Files are organized into directories
• Files can be stored on several kinds of physical
media
• Information access is largely controlled by file
access
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I/O Device Management
• A computer includes several I/O hardware
devices
• An operating system wraps an I/O subsystem
around each I/O device to:
– Hide the physical aspects of the device
– Provide a uniform software-based means of
accessing I/O devices
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Device Management
The device manager monitors every input/out put
device constantly to ensure that the device is
functioning properly.
 The device manager maintains a queue for each
input/output device or one or more queues for
similar input/output devices.
 The device manager controls the different policies
for accessing input/output devices.
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Security
• Concerned with the protection of:
– Electronically stored and manipulated
information
– Operating system
– Application-level information systems
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User Interface
• Each operating system has a user interface, a
program that accepts requests from users
(processes) and interprets them for the rest of
the operating system.
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Distinguish among multitasking, multiprocessing
and multiprogramming;
• Multiprogramming The ability of a computer to execute
two or more programs at the same time, using one CPU
(or processor).
• Multiprocessing The ability of a computer to execute
programs on two more processors simultaneously.
• Multitasking The concurrent execution (at the same time)
of two or more related tasks.
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explain the different types of processing
modes
• Batch processing system is one where
data is collected together in a batch before
processing starts e.g. Utility bills
Advantage
1. Jobs can be scheduled for a time when
the computer is not busy
Disadvantage
1. An expensive computer is required and a
well trained staff
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Real Time processing system- processes data
without significant delay making it always up to
date.
e.g. aeroplane landing control system, ticket
reservation.
Advantage
1. No significant delay for response
Disadvantages
1. The computer must be dedicated solely to the
task.
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Online Processing- is when computers and
peripheral devices are connected to a main
processor and turned on so that interaction can
take place.
e.g.printers
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• Time Sharing system- allows many
users to share time on a single
computer.
e.g. banks bank card system.
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Distinguish between types of user interface.
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Command-driven interfaces
Graphical user interface
Menu-driven interfaces
Direct manipulation interfaces
Special purpose interfaces
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Command interface
Commands enable the user to quickly and simply
instruct the computer what to do.
• Advantages of command-driven interface
• Faster to use, once you have learnt the
commands.
• Disadvantages of command-driven interface
• It is sometimes difficult to
• remember all the commands.
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GUI (Graphical User Interface)
This interface makes use of pictorial representations (icons)
and lists of menu items on a screen, which enable the user
to choose commands by pointing to the icons.
Just remember WIMP
 Windows
 Icons
 Menus
 Pointing devices
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• Advantages of GUIs
• •Fewer command errors
• •Reduced typing
• Disadvantages of GUIs
• •It may consume more screen .
• space
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Menu Driven
• The user is presented with a choice and, therefore, does not
have to remember any commands. The interface is,
therefore, suitable for beginners and infrequent users.
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• Pop-down menu: one that opens immediately
below the position of your mouse (or other
pointing device). You move the cursor
downward to go through the items in the menu
list.
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• Pop-up menu: any menu list that pops
• up on the screen, on demand, to offer
• you a choice of commands.
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Cont’d
Advantage of menu-driven interfaces
• The user is presented with a list of options to choose from,
they do not need to remember the commands.
• Disadvantage of menu-driven interface
• Several steps required to issue a command.
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