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Q. 1 Draw and explain the block diagram of computer?

Answer:

1. Input: This is the process of entering data and programs in to the computer system.

You should know that computer is an electronic machine like any other machine which

takes as inputs raw data and performs some processing giving out processed data.

Therefore, the input unit takes data from us to the computer in an organized manner for

processing.

2. Storage: The process of saving data and instructions permanently is known as storage.

Data has to be fed into the system before the actual processing starts. It is because the

processing speed of Central Processing Unit (CPU) is so fast that the data has to be

provided to CPU with the same speed. Therefore the data is first stored in the storage unit

for faster access and processing. This storage unit or the primary storage of the computer

system is designed to do the above functionality. It provides space for storing data and

instructions.

The storage unit performs the following major functions:

All data and instructions are stored here before and after processing. Intermediate results of processing are also stored here.

3. Processing: The task of performing operations like arithmetic and logical operations is

called processing. The Central Processing Unit (CPU) takes data and instructions from

the storage unit and makes all sorts of calculations based on the instructions given and

the type of data provided. It is then sent back to the storage unit.

4. Output: This is the process of producing results from the data for getting useful

information. Similarly the output produced by the computer after processing must also be

kept somewhere inside the computer before being given to you in human readable form.

Again the output is also stored inside the computer for further processing.

Block Diagram of Computer

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5. Control: The manner how instructions are executed and the above operations are

performed. Controlling of all operations like input, processing and output are performed

by control unit. It takes care of step by step processing of all operations inside the

computer.

FUNCTIONAL UNITS

In order to carry out the operations mentioned in the previous section the computer

allocates the task between its various functional units. The computer system is divided

into three separate units for its operation. They are

Arithmetic logical unit Control unit. Central processing unit.

Arithmetic Logical Unit (ALU): After you enter data through the input device it isstored in the primary storage unit. The actual processing of the data and instruction are

performed by Arithmetic Logical Unit. The major operations performed by the ALU are

addition, subtraction, multiplication, division, logic and comparison. Data is transferred

to ALU from storage unit when required. After processing the output is returned back to

storage unit for further processing or getting stored.

Control Unit (CU): The next component of computer is the Control Unit, which acts

like the supervisor seeing that things are done in proper fashion. Control Unit is

responsible for co ordinating various operations using time signal. The control unit

determines the sequence in which computer programs and instructions are executed.

Things like processing of programs stored in the main memory, interpretation of the

instructions and issuing of signals for other units of the computer to execute them. It also

acts as a switch board operator when several users access the computer simultaneously.

Thereby it coordinates the activities of computers peripheral equipment as they perform

the input and output.

Central Processing Unit (CPU): The ALU and the CU of a computer system are jointly

known as the central processing unit. You may call CPU as the brain of any computer

system. It is just like brain that takes all major decisions, makes all sorts of calculations

and directs different parts of the computer functions by activating and controlling the

operations.

Q. 2 Explain different generations of computers?

Answer: The development of computers has followed different steps in the terminology

used and these steps of technological differences are called as GENERATIONS in

computer terminology. There are totally five generations of computers till today.

1. First Generation Computers (1950's): These computer which used vacuum tubes

(valves) as major electronic component the advantage of vacuum tubes technology is that

it made the advent of Electronic digital computer vacuum tubes were only electronicdevices available during those days which made computing possible.

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Some of the computers of this generation were:

ENIAC: It was the first electronic computer built in 1946 at University of Pennsylvania,

USA by John Eckert and John Mauchy. It was named Electronic Numerical Integrator

and Calculator (ENIAC). The ENIAC was 30_ 50 feet long, weighed 30 tons, contained

18,000 vacuum tubes, 70,000 registers, 10,000 capacitors and required 150,000 watts ofelectricity. Today your favorite computer is many times as powerful as ENIAC, still size

is very small.

EDVAC: It stands for Electronic Discrete Variable Automatic Computer and was

developed in 1950. The concept of storing data and instructions inside the computer was

introduced here. This allowed much faster operation since the computer had rapid access

to both data and instructions. The other advantages of storing instruction were that

computer could do logical decision internally.

The limitations of the First Generations of computer are:

1. The operating speed was quite slow.2. Power consumption was very high.3. It required large space for installation.4. The programming capability was quite low.

2. Second Generation Computers (1960's):

With the development of Transistors and there use in circuits, magnetic core for memory

storage, the vacuum tubes are replaced by transistors to arrive at 2nd generation of

computers. The size of transistors is much smaller when compared to vacuum tubes, they

consume less power, generated less heat and faster and reliable.

Advantages:

1. Size of Computer has come down as well as power consumption.2. The Cost of Computer reduced.

Some of the computers of the Second Generation were

IBM 1620: Its size was smaller as compared to First Generation computers andmostly used for scientific purpose.

IBM 1401: Its size was small to medium and used for business applications. CDC 3600: Its size was large and is used for scientific purposes.

3. Third Generation Computers (1970's):

The development of silicon chips, the third generation of computers came into existence.

These computers are used Integrated Circuits (IC's) of silicon chips, in the place of

transistors. Each of these IC's consist of large number of chips in very small packages.

Advantages:

The size of computers, cost, heat generation and power consumption decreased to great

extent, speed and reliability increased as compared to previous generation. These

machines used IC's with large scale Integration (LSI).

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4. Fourth Generation (1980's): The Computers belonging to these generations used

Integrated circuits with Very Large Scale Integration (VLSI).

Advantages:

1. These computers have high processing powers, low maintenance, and highreliability and very low power consumption.

2. The size & cost of computers come down drastically5. Fifth Generation (Late 1990's): Fifth generation computing devices, based on

artificial intelligence, are still in development, though there are some applications, such

as voice recognition, that are being used today. The use of parallel processing and

superconductors is helping to make artificial intelligence a reality. Quantum computation

and molecular and nanotechnology will radically change the face of computers in years

to come. The goal of fifth-generation computing is to develop devices that respond to

natural language input and are capable of learning and self-organization.

Q. 3 What is the difference between Impact and Non impact printers? Give one

example of each.

Answer: An impact printer is a printer that strikes a print head against an ink ribbon to

mark the paper. Common examples include dot matrix and daisy-wheel printers. Dot

matrix printers strike the ribbon with a grid of metal pins, while daisy-wheel printers

strike the ribbon with a "petal" from a wheel of characters and symbols.

Impact printers still exist, but they have been largely replaced by non-impact

printers, such as laser and inkjet printers. These printers do not physically strike the paper

and therefore are much quieter than impact printers. While dot matrix printers could beheard by everyone in the office, laser and inkjet printers allow you to print documents

without distracting fellow employees.

Example: Dot matrix and daisy wheel printers are common types of impact

printers.

Most modern printers are called non-impact printers since they do not operating

by striking a print head against an ink ribbon. Two common types of non-impact printers

include inkjet printers, which spray small drops of ink onto each page, and laser printers,

which roll ink onto the paper using a cylindrical drum.

Non-impact printers are generally quieter and require less maintenance thanimpact printers, since they don't physically strike a ribbon against the paper. Of course, as

we all know, modern printers can still find other ways not to work properly.

Example: Inkjet and laser printers are common types of non-impact printers.

1. Non-impact printers are quieter and produce better quality print than impactprinters.

2. Non-impact printers, the characters and images are form without any directphysical contact of the paper.

3. Impact printers are noisily because of the hitting activity.4. Non-impact printers are usually more expensive than impact printers.

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5. In non-impact printers the text or image is formed without any physicalcontact of the paper and the printer head. But in impact printers the paper and

the printer head come in contact and hence the text or image is formed.

Q. 4 Differentiate between RAM and ROM?

Answer: RAM: Stands for "Random Access Memory," and is pronounced like the male

sheep. RAM is made up of small memory chips that form a memory module. These

modules are installed in the RAM slots on the motherboard of your computer. Every time

you open a program, it gets loaded from the hard drive into the RAM. This is because

reading data from the RAM is much faster than reading data from the hard drive.

Running programs from the RAM of the computer allows them to function without any

lag time. The more RAM your computer has, the more data can be loaded from the hard

drive into the RAM, which can effectively speed up your computer. In fact, adding RAM

can be more beneficial to your computer's performance than upgrading the CPU.

ROM: Stands for "Read-Only Memory." Please do not confuse this term with RAM or ahard drive, as many people already do. ROM is memory containing hardwired

instructions that the computer uses when it boots up, before the system software loads. In

PCs, the instructions are read from a small program in the ROM, called the BIOS (Basic

Input/output System)

Difference between RAM and ROM:

1. RAM is Random Access Memory, while ROM stands for Read Only Memory.2. RAM is volatile and is erased when the computer is switched off. ROM is non-

volatile and generally cannot be written to.

3.

RAM is used for both read and write while ROM is used only for reading.4. RAM needs electricity to flow to retain information while ROM is permanent.5. RAM is analogous to a blackboard on which information can be written with a

chalk and erased any number of times, while ROM is permanent and can only be

read. One example is BIOS (basic input output system) that runs when computer

is switched on and it prepares disk drives and processor to load OS from disk.

Q. 5. Define Operating System? Why it is necessary for a computer?

Answer: An operating system, abbreviated OS, is a product, software type that is part of

a system, equipment or computerized equipment, which deals with management andcoordination of its activities. The computerized system may be a computer, a

workstation, a server, a PC, a notebook, a smartphone, a road navigation device or

another system with "intelligence" of its own. The operating system plays the role of host

for all applications running on the equipment (hardware).

Operating system functions

To act as interface between hardware and users, an operating system must be able

perform the following functions:

1. Enabling start-up application programs. Thus, the operating system must have:a. A text editor

b. A translator

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c. An editor of links2. The allocation of resources needed to execute programs is done by identifying:

the programs that are running, the need for memory, peripheral devices and data

protection requirements.

3.

Facilities for data compression, sorting, mixing, cataloguing and maintenance oflibraries, through utility programs available.

4. Plan implementation works according to certain criteria, for efficient use ofcentral processing unit.

5. Assisting implementation of programs through computer-user communicationsystem, at both hardware and software level.

Examples of operating systems: BS2000, BS3000, DOS, PC-DOS, MS-DOS, LINUX,

SOLARIS, MAC OS, UNIX, WINDOWS-7 & WINDOWS-8.

Q. 7 Explain LAN and WAN with example.

Answer: LAN: (local area network) a group of computers that share a common

connection and are usually in a small area or even in the same building. For example an

office or home network. They are usually connected by Ethernet cables and have high

speed connections. If it was a wireless setup it would be called a WLAN, which would

have a lower connection speed.

Example: Local Area network

2 or more computers connected small office or an internet cafe

WAN: WAN (wide area network) this is the largest network and can interconnect

networks throughout the world and is not restricted to a geographical location. TheInternet is an example of a worldwide public WAN. Most WANs exist to connect LANs

that are not in the same geographical area. This technology is high speed and very

expensive to setup.

Example:

Internet VPN WAN links