HTML Declaration(Document Types)

The document type declaration tag is first tag in your in your HTML document, before the other html tags. It is not an HTML tag; it is an instruction that gives to the web browser about which version of HTML the page we are using.

DOCTYPE Declarations

In HTML 5 version<!DOCTYPE html>

In HTML 4.01 version

This DTD consist all HTML tags. but no include deprecated tag for example font. Frames are not allowed in this version.

<!DOCTYPE HTML PUBLIC "-//Type here.../DTD HTML 4.01//EN" >

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Generation of Computers

Generation of Computers – Computers were developed in different phases known as generations of computer. Depending upon the technologies used the development of electronic computers can be divided into five generations. 1. First generation The duration lasted from 1946-1959 was based on vacuum tubes . Because thousands of such bulbs were used, the computers were very large and generate a large amount of heat, causing many problems in temperature regulation. Magnetic drums were used for memory purpose and instruction and data was given through punch cards . Computer were operated manually and instruction given in machine language . E.g. – UNIVAC (Universal automatic computer), ENIAC (Electronic Numerical Integrator And Calculator ) , Mark I etc. Main Features – 1. Vacuum tube technology used 2. ...

Input and Output devices

Input device Input device is a device through which data and instruction are entered into computer system. An input devices converts the data and instructions into binary form that computer can understand. This transformation is performed by “Input interface”. The data entered through input device can be some text, some graphical image or symbol, sound etc, depending on the form of the raw data the various input devices are available. Basic Function Performed by Input unit of a computer system - 1. It accepts the instruction and data from the user. 2. It converts these instruction and data in computer acceptable form. 3. It supplies the converted instruction and data to the computer system for further processing. Some of the commonly input devices used are:- 1. Keyboard 2. Mouse 3. Joy stick 4. Track ball 5. Touch screen 6. Light Pen 7. Digitizer 8. Scanner 9. Speech Recognition Devices 1. Keyboard Keyboard is an input device for enteri...

Computer Memory

Memory : A memory is just like a human brain. It is used to store data and instructions. Computer memory is the storage space in computer where data is to be processed and instructions required for processing are stored. The memory is divided into large number of small parts. Each part is called cell. Each location or cell has a unique address, which varies from zero to memory size minus one. The computer storage memory is measure in term of Bytes. Eight bits make one Bytes. (Measure units) Primary Memory/Main Memory Primary memory holds only those data and instructions on which computer is currently working. Has limited capacity and data gets lost when power is switched off. It is also called main memory. It is generally made up of semiconductor device. These memories are not as fast as registers. The data and instructions required to be processed earlier reside in main memory. Characteristic of Main Memory · ...

Notes For BCA Students

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