Computer & Communications Systems

Software Development

Unit 1

Elements of Computer & Communications Systems

1. People

2. Procedures

3. Data/Information

4. Hardware

5. Software

6. 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

– 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:

– 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:– 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:– Microcomputers– Minicomputers– Mainframes– Supercomputers– Servers

Developments in Communication Technology

• 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