Transcript Computer & Communications Systems

Software Development
Unit 1
Computer & Communications
Systems
Elements of Computer &
Communications Systems
1.
2.
3.
4.
5.
6.
People
Procedures
Data/Information
Hardware
Software
Communications
1. People
• People are the most important part of a
computer and communications system.
• The whole purpose of a system is to benefit
people and to make their jobs easier.
• Two types of people who use computer
systems are
– Computer professionals and
– End users
• Computer professionals are people who
have had extensive education or
considerable experience in the technical
aspects of using a computer.
• End Users (users) are people with moderate
technical knowledge of information
technology who uses computers for
entertainment, education or work-related
tasks.
2. Procedures
• Procedures are descriptions of how things
are done - steps for accomplishing a result
or rules and guidelines for what is
acceptable.
• Step-by-step instructions on how to
complete a task.
3. Data/Information
• Data consists of the raw facts and figures that
have no meaning or usefulness.
• Data is processed into information using set
procedures.
• Information is summarised data or otherwise
manipulated data that is useful for decision
making.
3.1 Storage of data and information
• A computer systems data and information
storage capacity is represented by bits, bytes,
kilobytes, etc.
• Computers deal with ‘on’ and ‘off’ electrical
states, which are represented by 0s and 1s,
called bits.
• Bits are combined into groups of 8 called
bytes.
• One byte is equivalent to a character such as a
letter or number or special symbol.
• Kilobyte (KB)- equivalent to 1024 bytes
• Megabyte (MB) - equivalent to 1024 KB or
approximately 1 million bytes
• Gigabyte (GB) - equivalent to 1024 MB or
approximately 1 billion bytes
• Terabyte (TB) - equivalent to 1024 GB or
approximately 1 trillion bytes
3.2 Steps used in processing data
into information
• There are 9 steps in the processing of data
into information:
– Acquisition, Input, Validation,
Manipulation/Processing, Storage,
Retrieval, Output , Communication and
Disposal
4. Hardware
• There are 5 types of hardware devices:
– Input hardware
– Processing and Memory hardware
– Output hardware
– Secondary Storage hardware
– Communications hardware
4.1 Input Hardware
• Consists of devices that allow people to put data
into the computer in a form that the computer can
use eg
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Keyboard
Mouse
Microphone
Scanner
4.2 Processing & Memory
Hardware
• These devices are the ‘brains’ of the
computer. They include:
– the CPU - Central Processing Unit. The CPU is
usually the microprocessor in a computer.
– Main Memory - also known as RAM (Random
Access Memory)
– Motherboard, etc.
4.3 Output Hardware
• Consists of devices that translate
information processed by the computer into
a form that humans can understand.
• There are three principle types of output
hardware:
– Screens
– Printers
– Sound output devices
4.4 Secondary Storage Hardware
• Secondary storage consists of devices that store
data and programs permanently on disk or tape.
• Examples of secondary storage are:
– Floppy disks
– Hard disks
– Magnetic Tape
– CD ROM
– DVD ROM
4.5 Communications Hardware
• Communication hardware are used to
extend the range of computers.
• Examples of communication hardware are:
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Twisted pair wire
Coaxial cable
Fibre optics
Satellite transmission
Infrared transmission
modem
5. Software
• Software, or programs, consists of the
instructions that tell the computer how to
perform a task.
• There are two main types of software:
– Applications Software
– System Software
5.1 Applications Software
• Is software that has been developed to
– solve a particular problem,
– perform useful work on specific tasks
– to provide entertainment
• Application software can be either
– Custom software or
– Packaged software
5.1.1 Custom Software
• Is software designed and developed fo a
particular customer
• You would hire a programmer to develop
this software for you
5.1.2 Packaged Software
• Is the kind of off-the-shelf program
developed for sale to the general public,
such as:
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Word
Excel
Access
etc
5.2 System Software
• Controls the allocation and usage of
hardware resources and enables the
application software to run.
• Systems software consists of several
programs, the most important being the
Operating System.
5.2.3 Operating System Software
• The Operating System acts as the master control
program that runs the computer
• It handles activities such as
– running and storing programs and
– storing and processing data
• The OS allows applications to operate by allowing
access to shared resources such as printers,
modems, etc
• Examples of OS - Windows 2000, Linux,
MacOSX, Unix
6. Communications
• Communications is defined as the electronic
transfer of data from one place to another.
Developments in Computer
Technology
• Smaller size - a computer with a 12’’
monitor compared with a computer that
took up a whole room back in the 1960s
• More power - 1 GB RAM compared with 1
MB RAM a few years ago
• Less expense - approx $1500 for a top of
the range desktop computer compared with
$4000 a few years ago
Kinds Of Computers
• There are 5 kinds:
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Microcomputers
Minicomputers
Mainframes
Supercomputers
Servers
Developments in Communication
Technology
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Better communication channels
Networks
New sending and receiving devices
Online information access
Multimedia computers
Wireless pocket PCs
PC/TVs
etc
Ethics Of Information
Technology
• Ethics is defined as a set of moral values or
principals that govern the conduct of an
individual or a group.
– Speed and Scale has serious implications for data
security and privacy of information.
– Unpredictability - not as predictable as electricity,
television and cars.
– Complexity - because they are so complex,
computers can become unmanageable producing
massive foul-ups or out-of-control costs