Wireless Media

  It is also known as a wireless media. Wireless media transmit and receive electromagnetic signals without and electrical or optical conductor.  Here transmission and reception achieved by means of an antenna. For transmission antenna emits signal into medium and for reception antenna picks up electromagnetic signals from the surrounding medium. The two forms of transmission:

  Directional: - In this, transmitting antenna puts out a focused electromagnetic beam. The transmitting receiving antenna must be aligned, known as Point-to-Point Communication.

   Omni-directional: - In this the transmitted signal spreads out in all direction and be received by many antenna inspite of direction.

According to frequency range the wireless media is divided into three parts:-

·         Radiowave (30MHz-1GHz): Omni directional transmission

·         Microwave (1-40GHz): Point-to-Point Communication

·         Infrared (100GHz-1000 THz light frequencies): Local Point to Point, Multipoint application within confined areas.

Cable Transmission Media Comparison

Cable Transmission Media Comparison

Media	Cost	Ease of Installation	Capacity Range	Attenuation	Immunity from Interference
Unshielded Twisted Pair	Extremely Low	Very simple	1 to 100 Mbps	High, maximum effective range in 100s of meters	Low
Shielded Twisted Pair	Moderate	Simple to moderate	1 to 155 Mbps	High, maximum effective range in 100s of meters	Moderately low
Coaxial cable	Low to moderate	Simple	Varies by size and composition between 1 Mbps to Gbps	High, maximum effective range in low Kms	Moderate
Fiber Optic Cable	Moderate to high	Difficult	10 Mbps to Gbps	High, maximum effective range in 10s of Kms	High

Differences between analog and digital computers.

Analog Computer:

An analog computer is a form of computer that uses the continuously changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved. As an analog computer does not use discrete values, but rather continuous values, processes cannot be reliably repeated with exact equivalence.

 

Digital Computer: A digital computer is form computer that uses letters and numbers as inputs in processing and displays the result in monitors or other forms of output devices and can also store the output in memory to be used later. Following are some key differences between digital and analog computer

Analog Computer	No.	Digital Computer
This type of computer uses continuously changeable aspects of physical phenomena.	1	This type of computer runs by turning on and off electricity which are digital signals.
Electrical wave generated from pressure, temperature etc. such changeable data are used as input in analog computers.	2	Letters and numbers are used in digital computer to process data.
Analog computer uses physical devices like plotter etc. to display the output of an operation.	3	Digital computer can display output to monitor or on other devices.
Analog computers are less accurate.	4	Accuracy of digital computers is very high as it can take lot of decimal points into consideration in calculation
Speedometer, slide rule etc. are example analog computer	5	Generally all modern computers are digital computers such PC, laptop, notebook etc.

 

Computer Mouse

A computer mouse is a handheld hardware input device (also called Pointing device) that controls a cursor in a GUI and can move and select text, icons, files, and folders. For desktop computers, the mouse is placed on a flat surface such as a mouse pad or a desk and is placed in front of your computer.

Difference between Supercomputer & Mainframecomputer

Difference between Microcomputer, Minicomputer & Mainframecomputer

Assembler

An Assembler is a type of computer program that interprets software programs written in assembly language into machine language, code and instructions that can be executed by a computer.
An assembler enables software and application developers to access, operate and manage a computer's hardware architecture and components.
An assembler is sometimes referred to as the compiler of assembly language. It also provides the services of an interpreter.

Programming language processor that translates an assembly language program (the source program) to the machine language program (the object program) executable by a computer.

Read more: http://www.businessdictionary.com/definition/assembler.html

Programming language processor that translates an assembly language program (the source program) to the machine language program (the object program) executable by a computer.

Read more: http://www.businessdictionary.com/definition/assembler.html

Programming language processor that translates an assembly language program (the source program) to the machine language program (the object program) executable by a computer.

Read more: http://www.businessdictionary.com/definition/assembler.html

Programming language processor that translates an assembly language program (the source program) to the machine language program (the object program) executable by a computer.

Read more: http://www.businessdictionary.com/definition/assembler.html

COMPILER & INTERPRETER

A compiler is a program that translates the entire source program written in some high-level programming language (such as Java) into machine code for some computer architecture (such as the Intel Pentium architecture).

1. A computer program which reads entire source code and outputs assembly code or executable code is called compiler.
2. A program that translates software written in source code into instructions that a computer can understand Software used to translate the text that a programmer writes into a format the CPU can use.
3. A piece of software that takes third-generation language code and translates it into a specific assembly code. Compilers can be quite complicated pieces of software.

An Interpreter is a program that translates a source program written in some high-level programming language (such as BASIC) into machine code for some computer architecture (such as the Intel Pentium architecture) line by line.

1. A computer program which reads line by line source code and outputs assembly code or executable code is called interpreter.

Difference between Compiler and Interpreter

No	Compiler	Interpreter
1	Compiler Takes Entire program as input	Interpreter Takes Single instruction as input .
2	Intermediate Object Code is Generated	No Intermediate Object Code is Generated
3	Conditional Control Statements are Executes faster	Conditional Control Statements are Executes slower
4	Memory Requirement : More (Since Object Code is Generated)	Memory Requirement is Less
5	Program need not be compiled every time	Every time higher level program is converted into lower level program
6	Errors are displayed after entire program is checked	Errors are displayed for every instruction interpreted (if any)
7	Example : C Compiler	Example : BASIC