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Practical 1 :- Introduction of computer hardware:

The hardware are the parts of the computer itself including the Central Processing Unit (CPU) and

related microchips and micro-circuitry, keyboards, monitors, case and drives (hard, CD, DVD, floppy,

optical, tape, etc...). Other extra parts called peripheral components or devices include mouse, printers,

modems, scanners, digital cameras and cards (sound, colour, video) etc... Together they are often

referred to as a personal computer.


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1.Monitor 5.Expansion Cards

9.Keyboard

2.Motherboard 6.SMPS(Power supply)

10.Mouse

3.CPU 7.Optical disk drive

4.RAM 8.Hard disk drive

Keyboard:

The keyboard is used to type information into the computer or input information. There are many

different keyboard layouts and sizes with the most common for Latin based languages being the

QWERTY layout (named for the first 6 keys). The standard keyboard has 101 keys. Notebooks have

embedded keys accessible by special keys or by pressing key combinations (CTRL or Command and P

for example).Some of the keys have a special use. They are referred to as command keys. The 3 most

common are the Control (CTRL), Alternate (Alt) and the Shift keys.

Mouse:

Most modern computers today are run using a mouse controlled pointer. Generally if the mouse has

two buttons the left one is used to select objects and text and the right one is used to access menus. If

the mouse has one button, it controls all the activity and a mouse with a third button can be used byspecific software programs.One type of mouse has a round ball under the bottom of the mouse that rolls

and turns two wheels which control the direction of the pointer on the screen. Another type of mouse

uses an optical system to track the movement of the mouse. Laptop computers use touch pads, buttons

and other devices to control the pointer.


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Monitors

The monitor shows information on the screen when you type. This is called outputting information.

When the computer needs more information it will display a message on the screen, usually through a

dialog box. Monitors come in many types and sizes. The resolution of the monitor determines the

sharpness of the screen. The resolution can be adjusted to control the screen's display..Most desktop

computers use a monitor with a cathode tube or liquid crystal display. Most notebooks use a liquid

crystal display monitor.

CPU (Central Processing Unit):

CPU is the brain of computer system. All major calculations and comparisons performed by a computer

are carried out inside its CPU. CPU is also responsible for activating and controlling the operation of

other unit of a computer system. Hence, no other single components of a computer determines ifs

overall performance as much as its CPU. The central processing unit (CPU) is the portion of a

computer system that carries out the instructions of a computer program, to perform the basic

arithmetical, logical, and input/output operations of the system.

A simplified diagram of the

CPU

CU (Control Unit):

The control unit of the CPU

selects and interprets program

instruction and then

coordinates their execution. The control unit coordinates the input and output devices of a computer

system. It fetches the code of all of the instructions in the micro programs. It directs the operation of

the other units by providing timing and control signals. The control unit directs and controls the

activities of the internal and external devices. A control unit in general is a central part of the

machinery that controls its operation, provided which the term is specifically used is the area of

computer design.It does not perform any actual processing on data, the control unit acts as a central

nervous system for other components of a computer system.

Types of control unit:


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Fetching

Executed

Decode

Write back

ALU (Arithmetic Logic Unit)

In computing, an arithmetic logic unit (ALU) is a digital circuit that performs arithmetic and logical

operations. The ALU is a fundamental building block of the central processing unit of a computer, and

even the simplest microprocessors contain one for purposes such as maintaining timers. ALU of a CPU

is the place where actual execution of instruction takes place during data processing operation. Data

and instruction stored in primary storage before processing are transferred as and when needed to the

ALU where processing takes place. Intermediate results generated in the ALU are temporarily

transferred back to primary storage unit needed later. Hence, data may move from primary storage to

ALU and back again to storage many times before processing is over.

Register:

As instruction are interpreted and execution by a computers CPU, there is movement of information

between various units of the computer. These register are used to hold information on a temporary

basis and are parts of the CPU. Registers are a group of cells used for memory addressing, datamanipulation and processing. Some of the registers are general purpose and some are reserved for

certain functions.

Function of these register are described below:

1. Memory Address Register (MAR)

2. Memory Buffer Register (MBR)

3. Program Control Register (PC)

4. Accumulator Register (A)

5. Instruction Register (I)

6. Input/output Register (I/O)


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Memory

In computing, memory refers to the physical devices used to store programs data on a temporary or

permanent basis for use in a computer or other digital electronic device. The term primary memory is

used for the information in physical systems which are fast as a distinction from secondary memory,

which are physical devices for program and data storage which are slow to access but offer higher

memory capacity. Primary memory stored

on secondary memory is called "virtual memory". The term "memory" is often asociated with

addressable semiconductor memory, i.e. integrated circuits consisting of silicon-based transistors, used

for example as primary memory but also other purposes in computers and other digital electronic

devices.

There are two main types of semiconductor memory:

1. Volatile

2. Non-volatile

Examples of non-volatile memory are flash memory and ROM/PROM/EPROM/EEPROM memory.

Examples of volatile memory are primary memory (typically dynamic RAM, DRAM), and fast CPU

cache memory (typically static RAM, SRAM, which is fast but energy-consuming and offer lower

memory capacity per area unit than DRAM) .The semiconductor memory is organized into memory

cells or biteable flip-flops, each storing one binary bit (0 or 1). The memory cells are grouped into

words of fix word length, for example 1, 2, 4, 8, 16, 32, 64 or 128 bit. Each word can be accessed by a

binary address of N bit, making it possible to store 2 raised by N words in the memory.This implies

that processor registers normally are not considered as memory, since they only store one word and do

not include an addressing mechanism.

Types of memory:

1. Primary Memory

2. Secondary Memory

Motherboard:

The main circuit board of a microcomputer. The motherboard contains the connectors for attaching

additional boards. Typically, the motherboard contains the CPU, BIOS, memory, mass storage

interfaces, serial and parallel ports, expansion slots, and all the controllers required to control standard

peripheral devices, such as the display screen, keyboard, and disk drive. Collectively, all these chips


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that reside on the motherboard are known as the motherboard's chipset. On most PCs, it is possible to

add memory chips directly to the motherboard. You may also be able to upgrade to a faster PC by

replacing the CPU chip. To add additional core features, you may need to replace the motherboard

entirely. Motherboard is sometimes abbreviated as mob

.

A block diagram of a

modern motherboard,

which supports many

on-board peripheral

functions as well as

several expansion

slots.

Storage

device:Data andinstructions entered

into a computer

system through input

units have to be stored

inside the computer

before actualprocessing start.

Similarly, result

produced by a

computer after

processing have to be

kept somewhere inside

the computer system before being passed on to an output unit. Storage unit of a computer system caters

to all these needs. It provides space for storing data and instruction, intermediate results and results for

output.

In short, a storage unit holds:

1. Data and instruction required for processing (received from input device)

2. Intermediate results of processing.

3. Results of output, before they are released to an output device.


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Storage unit of all computers is comprised of following two types of storage:

Primary storage: Primary storage of a computer, also known as its main memory, is used to

hold piece of program instruction and data, intermediate results of processing on which the

computer is currently working. These pieces of information are representation electronically in

the main memory chips circuitry and central processing unit can access it directly at a very fast

speed. However, primary storage can hold information only while computer system is on. As

soon as the computer system switches off or resets, the information held in primary storage is

erased.

Secondary storage: Secondary storage of a computer, also as its auxiliary storage, is used

to take care of the primary storage. That is, it supplements the limited storage capacity and the

volatile characteristic of primary storage. This is because secondary storage is much cheaper

than primary storage and it can retain information even when a computer system switches off or

resets. Secondary storage holds the program instructions, data, and information of those jobs onwhich the computer system is currently not working but needs to hold them for processing later.

Magnetic disk is the most commonly used secondary storage medium.

I/O device: (input and output device)

Input device: Data and instruction must enter a computer system before the computer can perform

any computation on the supplied data. The input unit that links a computer with its external

environment performs this task. Data and instruction enter a computer through an input unit in a form

that depends upon the input device used. For example, data can be entered using a keyboard in a

manner similar to typing and this differ from the way in which data is entered through a scanner

another type of input device. However, a computers memory is designed to accept input in binary code

and hence, all inputs device must transform input signals to binary codes. Units called inputinterface

accomplishthis transformation. Input interfaces match the unique physical or electrical characteristics

of input device to the requirements of a computer system.

In short, an input unit perform following functions:

It accepts instructions and data from outside world.

It converts these instruction and data in computer acceptable form.

It supplies the converted instruction and data to computer system for further processing.


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Output device: An output unit performs the reverse operation of that of an input unit. It supplies

information obtained from data processing to outside world. Hence, it links a computer with its external

environment. As computers work with binary code, results produced are also in binary form. Therefore,

before supplying the result to outside world, the system must convert them to human acceptable form.

Units called output interface accomplish this task. Output interfaces match the unique physical or

electrical characteristics of output devices (terminals, printers, etc.) to the requirements of an external

environment.

In short an output unit perform following functions:

It accepts the results produced by a computer, which are in coded form and hence, we cannot

easily understand them.

It converts these coded results to human acceptable form.

It supplies the converted results to outside world.

Modem:

A modem is a device that modulates an analogy carrier signal to encode digital information, and also

demodulates such a carrier signal to decode the transmitted information. Modems can be used over any

means of transmitting analogy signals, from light emitting diodes to radio. Modems are generally

classified by the amount of data they can send in a given unit of time, usually expressed in bits per

second (bit/s, or bps). Modems can alternatively be classified by their symbol rate, measured in baud.

For example, the ITU V.21 standard used audio frequency-shift keying the original ITU V.22 standard,

which was able to transmit and receive four distinct symbols (two bits per symbol).

Modem is an essential

piece of hardware for

any application in

which two digital

devices want to

communicate over an

analogue transmission

channel. When we want to use a modem with your computer to allow it to communicate with any other

computer via telephone line, following factors should be considered:-

Transmission speed.

Internal versus external.

Facsimile facility.


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Router:

In packet-

switched networks

such as the Internet,

a router is a device

or, in some cases,

software in a

computer, that

determines the next

network point to

which a packet

should be forwarded

toward its

destination. The

router is connectedto at least two networks and decides which way to send each information packet based on its current

understanding of the state of the networks it is connected to. A router is located at any gateway

including each point-of-presence on the Internet.A router may create or maintain a table of the

available routes and their conditions and use this information along with distance and cost algorithms

to determine the best route for a given packet.

A block diagram of LAN router

Cabling:

Cable is the medium through which information usually moves from one network device to another.

There are several types of cable which are commonly used with LANs. In some cases, a network will

utilize only one type of cable, other networks will use a variety of cable types. The type of cable chosen

for a network is related to the network's topology, protocol, and size. Understanding the characteristics

of different types of cable and how they relate to other aspects of a network is necessary for the

development of a successful network.

The following sections discuss the types of cables used in networks and other related

topics:

1. Unshielded Twisted Pair (UTP) Cable

2. Shielded Twisted Pair (STP) Cable

3. Coaxial Cable

4. Fibre Optic Cable


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5. Cable Installation Guides

6. Wireless LANs

Unshielded Twisted Pair:Twisted pair cabling comes in two varieties:

Shielded

Unshielded

Unshielded twisted pair (UTP) is the most popular and is generally the best option for school

networks.

Unshielded twisted pair

The quality of UTP may vary from telephone-grade wire to extremely high-speed cable. The cable has

four pairs of wires inside the jacket. Each pair is twisted with a different number of twists per inch to

help eliminate interference from adjacent pairs and other electrical devices. The EIA/TIA (Electronic

Industry Association/Telecommunication Industry Association) has established standards of UTP and

rated six categories of wire.

Categories of Unshielded Twisted Pair:

Category speed use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps Local Talk & Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet


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1000 Mbps (4 pair) Gigabit Ethernet

5e 1,000 Mbps Gigabit Ethernet

6 10,000 Mbps Gigabit Ethernet

Unshielded Twisted Pair Connector:

The standard connector for unshielded twisted pair cabling is an RJ-45 connector. This is a plastic

connector that looks like a large telephone-style connector (See fig. 2). A slot allows the RJ-45 to be

inserted only one way. RJ stands for Registered Jack, implying that the connector follows a standard

borrowed from the telephone industry. This standard designates which wire goes with each pin inside

the connector.

Fig.2. RJ-45

connector

Shielded Twisted Pair Cable: (STP)

Although UTP cable is the least expensive cable, it may be susceptible to radio and electrical frequency

interference. If you must place cable in environments with lots of potential interference, or if you must

place cable in extremely sensitive environments that may be susceptible to the electrical current in the

UTP, shielded twisted pair may be the solution. Shielded cables can also help to extend the maximum

distance of the cables.

Shielded twisted pair cable is available in three different configurations:

Each pair of wires is individually shielded with foil.

There is a foil or braid shield inside the jacket covering all wires (as a group).

There is a shield around each individual pair, as well as around the entire group of wires

(referred to as double shield twisted pair).


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Coaxial Cable:

Coaxial cabling has a single copper conductor at its centre. A plastic layer provides insulation between

the centre conductor and a braided metal shield (See fig. 3). The metal shield helps to block any outside

interference from fluorescent lights, motors, and other computers.

Fig.3. Coaxial cable

Fibre Optic Cable:

Fibre optic cabling consists of a centre glass core surrounded by several layers of protective materials.

It transmits light rather than electronic signals eliminating the problem of electrical interference. This

makes it ideal for certain environments that contain a large amount of electrical interference. It has alsomade it the standard for connecting networks between buildings, due to its immunity to the effects of

moisture and lighting.

Fig.5. Fibre

optic cable

There are two common types of fibre cables:--

1. Single mode.

2. Multimode.

Installing Cable - Some Guidelines:

When running cable, it is best to follow a few simple rules:

1. Always use more cable than you need. Leave plenty of slack

2. Test every part of a network as you install it. Even if it is brand new, it may have problems that will

be difficult to isolate later.

3. Stay at least 3 feet away from fluorescent light boxes and other sources of electrical interference.

4. If it is necessary to run cable across the floor, cover the cable with cable protectors.

5. Label both ends of each cable.


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