About Basic
Computer Hardware
Every
part of your computer is the result of years of research and development. Parts
that were once hand made at a cost of thousands of man-hours are now mass
produced for a fraction of a rupee. Computer parts can be divided into two
groups, hardware and software.
Hardware
is any part of the computer that you can touch. The seeming miles of wires that
get tangled on your desk, the CD drive, the monitor are all hardware. Software
is a set of electronic instructions consisting of complex codes (Programs) that
make the computer perform tasks. Windows is a software, so is any other program
that runs on your computer.
While
there are thousands of parts even in the smallest computers that make up its
hardware, you are not required to know them all. You only need to know about
basic computer hardware.
Basic
computer hardware consists of the following parts:
1. CPU (Central Processing Unit)
The
CPU is considered the brain of the computer. It performs all types of data
processing operations, stores data, intermediate results and instructions
(program). It controls the operation of all parts of computer. A CPU has 3
components as listed below.
(A) CU (Control Unit)
The control unit (CU) is a component of a computer’s
central processing unit (CPU) that directs operations of the processor. It
tells the computer’s memory, arithmetic logic unit and input and output devices how to respond to a
program’s instructions. However, the Control Unit doesn’t process any data.
(B) ALU (Arithmetic Logic Unit)
Think
of the ALU as the logical part of the brain. When any mathematical calculation
or decision/logic needs to be carried out, the instruction is passed on to the
ALU. The ALU thinks in bits (i.e. binary digits – ‘0’s and ‘1’s.)
It
is made up of a group of memory locations built directly into the CPU called
registers. These are used to hold the data (binary information) that are being
processed by the current instruction.
(C) Memory
Primary
memory is memory that is part of the computer itself and necessary for its
functioning. It consists of mainly two types of memories:
(i) Random Access Memory (RAM)
RAM
is the internal memory of the CPU for storing data, program and program result.
It is read/write memory which stores data until the machine is working. As soon
as the machine is switched off, data is erased. RAM is volatile. Volatile means
that the data stored in memory is lost when we switch off the computer or if
there is a power failure. Hence a backup Uninterruptible Power System (UPS) is
often used with computers. There are different types of RAM available. Some of
them are described below.
·
Dynamic Random
Access Memory (DRAM): A type of physical memory used in most
personal computers. The term dynamic indicates that the memory must be
constantly refreshed or it loses its contents. This type of memory is more
economical.
·
Static Random
Access Memory (SRAM): A type of memory that is faster and less
volatile than DRAM, but requires more power and is more expensive. The term
static is derived from the fact that it does not need to be refreshed like
DRAM.
·
Synchronous Dynamic
Random Access Memory (SDRAM): A type of DRAM that has a much higher
processing speed.
(ii) Read Only Memory (ROM)
The
memory from which we can only read but cannot write on it. This type of memory
is non-volatile. The information is stored permanently in such memories during
manufacture. A ROM, stores such instructions that are required to start a
computer. This operation is referred to as bootstrap. The different types of
ROM are given below.
·
MROM (Masked ROM): The very first ROMs were
hard-wired devices that contained a pre-programmed set of data or instructions.
These kinds of ROMs are known as masked ROMs which are inexpensive. The MROM
cannot be programmed by the user.
·
PROM (Programmable
Read only Memory): PROM is read-only memory that can be modified
only once by a user. The user buys a blank PROM and enters the desired contents
using a PROM program.
·
EPROM (Erasable and
Programmable Read Only Memory): The EPROM is a type of a PROM which can be
programmed by the user multiple times. EPROM is erased by exposing it to
ultra-violet light for a duration of up to 40 minutes. Usually, an EPROM eraser
achieves this function.
·
EEPROM (Elastically
Erasable and Programmable Read Only Memory): The EEPROM is programmed
and erased electrically. It can be erased and reprogrammed about ten thousand
times. Both erasing and programming take about 4 to 10 milliseconds.
2. Secondary Storage (External Storage Devices)
Floppy
diskettes, hard disk, tapes and optical disks come under the category of
external storage devices or ancillary storage devices. These devices are very
sensitive to environmental conditions (humidity and temperature) as well as to
external magnetic fields and need to be stored carefully. They are not
compulsory for the functioning of the computer but are useful for expanding the
computer’s memory.
(A) Floppy Disk
Floppy
disks are primarily used on PCs. Information on a floppy disk is recorded in
the magnetized states of particles of iron oxides evenly placed upon concentric
circles known as tracks.
(B) Hard Disk
It
is a non-removable enclosed magnetic disk included in most PCs. It contains a
stack of metal platters, each coated with iron oxide, that spin on a spindle
and the entire unit is encased in a sealed chamber.
(C) Magnetic Tape
This
is plastic tape, usually made of Mylar that is coated with iron oxide, thereby
enabling the introduction (writing); retention (memory) and reading of
magnetically recorded information. The best use of tape storage is for data
that you do not use very often.
(D) Optical Disc Drive
An optical
disc drive (ODD) is a disk drive that uses laser light or
electromagnetic waves for reading or writing data to or from optical discs
(normally CD-ROM). A CD-ROM is a pre-pressed optical compact disc
which contains data. The name is an acronym which stands for “Compact Disc
Read-Only Memory”. Computers can read CD-ROMs, but cannot write
to CD-ROMs which are not writable or erasable.
(E) USB
A USB
flash drive, also commonly known as a USB drive, USB stick and a
variety of other names. It is a data storage device that
includes flash memory with an integrated USB interface. USB
flash drives are typically removable and rewritable, and physically much
smaller than an optical disc.
(3) Peripherals
Peripheral
devices are devices connected to the computer externally. If a peripheral
device is disconnected, the computer will still be able to work; only functions
performed by this peripheral device will not be available. Here are the most
used types of peripheral devices:
(A) Keyboard
The
most common and very popular input device which helps in inputting data to the
computer. It consists of keys that are capable of inputting alphabets, numbers
and special characters. You can also navigate using the keyboard and perform
shortcut functions.
(B) Mouse
Mouse
is the most popular pointing device and cursor-control device having a small
palm size box with a round ball at its base which senses the movement of mouse
and sends corresponding signals to CPU when the mouse buttons are pressed.
(C) Monitors
Monitors,
commonly called as Visual Display Unit (VDU), are the main output device of a
computer. It forms images from tiny dots, called pixels that are arranged in a
rectangular form. The sharpness of the image depends upon the number of pixels.
(D) Printer
Printer
is an output device, which is used to print information on paper.
·
Impact Printers: The impact printers print
the characters by striking them on the ribbon which is then pressed on the
paper.
·
Non-Impact
Printers: Non-impact printers print the characters
without using ribbon. These printers print a complete page at a time so they
are also called as Page Printers. Laser Printers, Inkjet Printers.
(E) Joy Stick
It
is a device used to move cursor position on a monitor screen. It is mainly used
in Computer Aided Designing (CAD) and playing computer games.
(F) Scanner
A
scanner allows you to scan printed material and convert it into a file format
that may be used within the PC.
(G) Plotter
A
plotter is used to create high-quality visuals on paper. Plotters were used in
applications such as computer-aided design, though they have generally
been replaced with wide-format conventional printers. A plotter gives a hard
copy of the output. It draws pictures on a paper using a pen. It can be used to
create presentation-charts, graphics, tables and high quality technical
drawings. There are two types of plotter.
·
Drum Plotter: The paper is placed over
the drum that rotates back and forth. A carriage holding one or more pens is
mounted horizontally across the drum. The carriage with the pens moves
horizontally over the paper. Each pen could be filled with different colours.
This plotter has the ability to produce colour pictures.
·
Flat Bed Plotter: In flat bed plotter, the
paper does not move. The carriage holding the pens should provide all motions.
Inkjet plotters can also produce large drawings with different colours.
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