Introduction to Computer Hardware and Software
Introduction to Computer Hardware and Software
PLATFORM
The
word computer is derived from compute. Compute is a Latin word. If means that
the combinations of many things. So we refer computer as the combination of
different thing i.e. Hardware and software. Platform means the combination of
hardware and software. We simply divide platform into two different
categories:-
1.
Hardware
2.
Software
COMPUTER
Computer is an
electronic device. It is used to solve problems according to a set of
instructions given to it. It solves a problem by dividing it into extremely
simple steps. It uses electronic pulses to execute instruction. Computer is
also considered as dull minded clerk. Computer doesn’t know what kind of
instruction it is going to perform. It simply executes the given task according
to the instructions given to it by the user of the computer.
HARDWARE
Hardware is the
tangible part of the computer. We can touch, see, feel and wear out components
of hardware. Any thing that has physical appearance and carries weight is
called hardware.
1.
Hard Disk
The hard disk is
also called the fixed disk. It consist of one or more
metal plates
that are coated with magnetizable material. The plates of the disk are fixed
permanently in the drive. The hard disk has following characteristics:-
§
The storage capacity of the
hard disk is much greater than that of the floppy disk. In microcomputers, the
storage capacity of a hard disk is generally 20 gigabytes (20GB), 40 gigabytes
(40GB), 80 gigabytes (80GB) and more.
§
The Data accessing speed is
very fast as compared with floppy drive.
§
It is very sensitive
device. This device is sealed and there are less chance of disk damage due to
dust and mishandling.
§
This device is storage
device. All data permanently resides on it in the form of bits, 0s and 1s,
binary, digital/signals/current. 0 means non availability of data and current
and 1 means availability of current, data and signal.
2.
RAM
Ram stands for random access memory.
It is also the essential part of the Computer. All the execution of the
instructions and data are performed in ram. Programs loads in the ram from the
hard disk for execution.
When we close any program and application and save our file, the data of
the file saves permanently on the hard disk from ram. Ram contains data in the
form of addresses. Ram is also considered as main memory. The main memory is
the most important component of the computer.
It is used to store data and instructions that are currently in use. Some
time main memory is also referred to as working area of the computer. The data
and program instructions are loaded into main memory before execution. A
computer cannot work without having main memory.
The main memory used in modern
computer is built-in in the form of chip. This chip is made of semi-conductor
material. The main memory consists of thousands or even millions of cells. Each
cell can store “0” and “1” bit. These cells are logically organized into groups
of 8-bits, called a byte. Each byte in the memory is assigned a unique address.
This number is called the address of that byte. The scheme of arranging cells
into bytes is shown below
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01001010 |
011110010 |
01001001 |
01010001 |
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This device is considered as the brain of the computer. It is the most essential
part of the computer hard ware. It executed all the instruction initiated by
the user of the computer and the program that is being operated by the user.
It is also considered as CPU. CPU
stands for Central Processing Unit. CPU performs all operations on data
according to programs instructions. It executes the program instructions and
tells the other parts of the computer hardware what to do. Mostly it performs
the work of calculations and data transportations. In data transportations, CPU
sends and receives data to and from different components of the computer.
CPU is located on the motherboard
inside the system unit. All other components of computer are connected to it through
the bus interconnection. It is further divided into two main components i.e.
Control Unit and Arithmetic Logic Unit.
(a) Control Unit
Control unit is the most important part of CPU. It acts as supervisor of
the computer. It controls all parts of the computer and coordinates all
activities in the computer. For example, it receives that data and instruction
from the input device and executed the instructions one by one.
(i)
Execution of Instructions
Control Unit
controls the operations of all part of the computer system. It also executes
the instructions given to the computer. Execution of an instruction by the
Control Unit consists of for simple steps.
a.
Instruction fetch
Control Unit
gets a program instruction stored in the main memory of the computer. This is
called fetching instruction.
b.
Interrupt Instruction
Control Unit
then decodes or examines an instruction to find out what action is to be taken to
successfully execute it. This process is called interpretation of the
instruction.
c.
Data Fetch
If an
instruction requires certain data to operate upon, the Control Unit obtains the
data from the computer memory and loads it into a register. This is called
fetching of data.
d.
Execute Instruction
After decoding
the instruction and getting the required data, the Control Unit sends the
instruction to ALU for execution.
(b) ALU
ALU stands for Arithmetic and Logic Unit. It is another important
component of CPU. It performs all the arithmetic and logical operations on the
data.
§
In arithmetic operations,
ALU performs the addition, subtractions, multiplication and division.
§
In logical operations, ALU
compares the numerical data as well as alphabetic data. For example, it checks
first number is greater than second, less than second or equal to second etc.
(i)
Arithmetic Instructions
The
Instructions that are used to perform arithmetic operations of addition,
subtraction, multiplication and division are called arithmetic instruction.
These instructions are executed by arithmetic section of ALU.
(ii)
Logical Instructions
The
Instructions that are used to compare two data items with each other are called
logical instructions. These instructions are executed by logic section of ALU.
(iii)
Data Transfer Instructions
The
instructions that are used to transfer data from one unit to another during
program execution are called data transfer instruction. For example, these
instructions are used to transfer data from the RAM to the CPU registers.
(iv)
Control Transfer
Instructions
The
instructions that are used to transfer the execution control from one part of
the program to another during program execution are called control transfer
instructions.
REGISTERS
Registers
are special purpose high speed memory is inside the CPU. These are small in
size but very efficient in working. These are used for the following purposes:-
(i)
Temporary storage of memory
addresses.
(ii)
Temporary storage of
instructions during execution of the program
(iii)
Temporary storage of data
being worked upon by the CPU.
Accumulator
A, Accumulator B, Accumulator C, Accumulator D, Stack Control Register, Index
Register, Index Register, Stack Control Register, Segment Register.
e.
Accumulator Register
f.
Stack Control Register
g.
Instructions Pointer Register
h.
Flag Register
i.
Address or segment registers
The accumulator register is used during logical and arithmetic
operations of the CPU. It is a part of the ALU.
b.
Stack control register
A stack is a set of memory locations in the main memory in which data is
stored and retrieved in an order. The data is stored and retrieved in Last In
First Out (LIFO) order. The stack control register is used to manage the
stacks.
c.
Instruction pointer
register
The Instruction register points to the memory location that holds the
instruction that is to be executed next by the Control Unit. It works in
combination with segment register CS.
d.
Address or segment register
The address register hold addresses of the memory locations that are
being currently accessed by the Control Unit. These registers are also called
segment registers. They are used in combinations with IP register or with Index
registers, DI and SI.
e.
Flag Register
The flag register is used to indicate occurrence of a certain condition
during an operation of the CPU. Each CPU contains a one byte or two byte flag
register. One byte consists of 8 bits and each bit of the flag register is used
to indicate a condition. Since each bit indicates a specific condition, it is
called a flag.
For example, if the result of a
calculation is zero and zero value is put into the accumulator, the value of
the Zero flag bit in the flag register will become “1” otherwise, it will
remains as “0”.
4. Mother Board
5.
Floppy Disk
Floppy diskette is also called simply a diskette or a disk. It is a small
flexible plastic disk that is coated with magnetizable material. It was
invented by IBM in early 1960s. The 3.5- inch diameter disk is also called
micro floppy disk. It is covered in a hard plastic jacket.
The read/write window of micro disk is always closed with a metal
shutter. The shutter and the hard plastic jacket provide production to the disk
damage from dust and mishandling. The shutter automatically opens when the disk
is inserted into the disk drive.
The jacket of the micro disk has a notch at one of its corners. Moving a small tab upward closes the notch, and the micro disk becomes write-protected.
6.
Mouse
7.
Key Board
8.
Monitor
9.
Printer
10.
Fax
11. Scanner
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