Hardware Basics

Computer :-

The word "computer" comes from the word "compute" which means to calculate. So a computer is normally considered to be a calculating device that can perform arithmetic operations at enormous speed. In fact, the original objective for inventing the computer was to create a fast calculating machine. But more than 80% of the work done by the computers today is of non-mathematical or non-numerical nature.


More accurately, a computer may be defined as a device that operates upon information or data. Data can be anything like bio-data of various applicants when the computer is used for recruiting personnel or the marks obtained by various students in various subjects when the computer is used to prepare results, etc. The data comes in various shapes and sizes depending upon the type of computer application. A computer can store, process and retrieve data as and when desired. 


Today's computers are electronic devices, and electronic signals are all it can understand. Because of this, it was necessary to develop a code that could translate things like numbers and letters (which the computer can not recognize) into electronic symbols. Any electronic device understands two states (on or off), this was used as the building block for this code. This on/off (1=on and 0=off) state is called a binary digit or bit. Since this is such a small amount of information, it is usually easier to talk about bytes of information ( a byte is a set of eight bits). By grouping the bits in groups of eight, we have the ability to represent up to 256 different codes. 


A basic computer has four key components, the CPU (Central Processing Unit) or processor or microprocessor, input and output (I/O) expansion such as keyboard, display and disk storage. Other components primarily support them, such as the motherboard, buses, expansion cards or power supply unit. The motherboard brings together individual boards that used to be housed separately, before personal computers. The processor, memory, serial ports, parallel port, keyboard interface, disk interface and buses. The processor executes instructions at low level and knows how to add, subtract and simple logical functions. The computers memory is workspace for all activity and is limited by the size. The number and variety of applications that can be made available at any one time is largely determined by the amount of memory, usually in megabytes (MB), millions of bytes (kilobytes are thousands of bytes, KB). Input and output (I/O) is used by the computer to read and write data using I/O devices called peripherals, including the monitor, printer or storage devices. Storage devices are used to keep data stored, when it is not in the computers memory.