memories are volatile in nature. External cache is mounted on the motherboard. Registers
are small memory units internally available within the processor.
Input devices accept data and control signals from the user. Output devices
communicate the processed data to the user. Examples of input devices are keyboard,
mouse, pen based systems, data scanners, game controllers, voice recognition systems
etc. Examples of output devices are Monitor, Printer, Plotter, sound system etc.
Central Processing Unit (CPU) -It is the brain of the computer. It performs the bulk of
the data processing operations. The function of the processor is to fetch the instruction
from memory, examine (decode) the instruction and execute the instructions. It consists
of Control unit, Arithmetic Logic Unit (ALU) and registers. Control unit is responsible
for fetching the instructions from memory and interpreting them. ALU performs
arithmetic and logical operations. Registers are very high speed memory units
for storing very small amount of data. Program counter, Instruction register, Memory
address register, memory buffer register and accumulator are some examples of registers.
Bus is a collection of wires. They may be unidirectional or bidirectional. Bus is used
to connect different parts of a computer. Bus may be serial or parallel. USB is an
example of a serial bus. Bus connecting computer and a dot matrix printer is normally
a parallel bus. Parallel bus carries several bits at a time. These bits may indicate
instruction, data, address or commands. Bus width and Bus speed are the two major
components for performance measure of a computer.
Collection of computer programs, procedures and documentation that perform some
tasks on a computer is called software. Software can be categorized as application
software and system software. -Application software is developed to solve a specific
problem. Examples: Notepad, Wordpad, Microsoft excel, MSAccess etc.. System
software provides a convenient environment for program development and execution.
Examples: Operating system, assemblers, compilers, interpreters, loaders and linkers
Compiler converts a high level program to a binary level program called object code.
Interpreter also does the same thing, but line by line and it also executes the line of code.
Operating system is responsible for the management of resources of computer. Examples
of Operating system: DOS,Windows, Unix, Linux, Mac, Solaris, AIX etc… DOS (Disk
Operating System) is a single user O.S., Unix is a multi user operating system. Windows
is multitasking operating system. Linux is a free Unix like operating system. Various
versions of Windows operating systems have been released by Microsoft like Windows95, Windows-98,Windows Me, Windows-XP, Windows-Vista, Windows-2003 etc. Unix
O.S. was developed by AT&T Bell Labs and comes either as AT&T Unix or BSD Unix.
Linux operating system comes in various distributions like Ubuntu, Fedora,redhat etc.
Mac O.S. is from Apple company and Solaris is from Sun Microsystems.
A computer network, often simply referred to as a network, is a collection of
computers and devices connected by communication channels that facilitates
communications among users and allows users to share resources with other users.