Computers, in
simple words, are machines that perform a set of functions according to their
users’ directions. Going by this definition, several electronic devices, from
laptops to calculators, are computers.
A
computer comprises of some basic elements.
These include hardware, software, programs,
data and connectivity. No computer can function in the absence of these
elements. Apart from these elements, a computer system comprises of three
basic
components. These components are responsible for making computers actually
function.
Let’s take a
look at them in detail.
Components
of a Computer System
Every computer
system has the following three basic components:
•Input unit
•Central processing unit
•Output unit
I/O devices are the pieces of hardware used by a human
(or other system) to communicate with a computer. For instance, a keyboard or
computer mouse is an input device for a computer, while monitors and printers
are output devices. Devices for communication between computers, such as modems
and network cards, typically perform both input and output operations.
The
designation of a device as either input or output depends on perspective. Mice
and keyboards take physical movements that the human user outputs and convert
them into input signals that a computer can understand; the output from these
devices is the computer's input. Similarly, printers and monitors
take signals that a computer outputs as input, and they convert these signals
into a representation that human users can understand. From the human user's
perspective, the process of reading or seeing these representations is
receiving output; this type of interaction between computers and humans is
studied in the field of human–computer interaction. A further
complication is that a device traditionally considered an input device, e.g., card
reader, keyboard, may accept control commands to, e.g., select stacker,
display keyboard lights, while a device traditionally considered as an
output device may provide status data, e.g., low toner, out of paper, paper
jam.
In
computer architecture, the combination of the CPU and main memory, to
which the CPU can read or write directly using individual instructions,
is considered the brain of a computer. Any transfer of information to or from
the CPU/memory combo, for example by reading data from a disk drive, is
considered I/O.The CPU and its supporting circuitry may provide
memory-mapped I/O that is used in low-level computer programming, such
as in the implementation of device drivers, or may provide access to I/O
channels. An I/O algorithm is one designed to exploit locality and
perform efficiently when exchanging data with a secondary storage device, such
as a disk drive.
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