Tutorial

Class 11 (CBSE)

Chapter 1

Computer Fundamentals

A) Name at least four early calculating devices.

Answer:

Abacus

Napier’s Logs and Bones

Pascaline

Leibnitz’s Calculator

B) Name the first operational general purpose computer.

Answer:

Mark 1  

C) Who first proposed the concept of ‘Stored Program Computer’?

Answer:

In 1945, Dr. John Von Neumann proposed the concept of a stored program computer.

As per this concept the program and data could be stored in the same memory unit

D) Define the IPO cycle.

Answer:

Every task given to a computer follows an Input- Process- Output Cycle (IPO cycle). It

needs certain input, processes that input and produces the desired output. The input

unit takes the input, the central processing unit does the processing of data and the

output unit produces the output. The memory unit holds the data and instructions

during the processing.

E) Differentiate between data and information.

Answer:

Data: It is the term used for raw facts and figures. For example, 134, + 9, ‘Raju’, ‘C’ are

data. Definition of information should start from next line as given in the word file. In

composed file it is starting from the same line immediately after the definition of data.

Information: Data represented in useful and meaningful form is information. In simple

words we can say that data is the raw material that is processed to give meaningful,

ordered or structured information. For example Raju is 9 years old. This is information

about Raju and conveys some meaning. This conversion of data to information is called

data processing.

F) Explain the Von Neumann Computer.

Answer:

In 1945, Dr. John Von Neumann proposed the concept of a stored program computer.

As per this concept the program and data could be stored in the same memory unit. The

basic architecture of the Von Neumann computer is shown in the figure below

Digram :

                       

According to Von Neumann architecture, the processor executes instructions stored in

the memory of the computer. Since there is only one communication channel, the

processor at a time can either fetch data or an instruction. That means at one point of

time either the data or an instruction can be picked (fetched) from the storage unit for

execution by the processor. Hence execution takes place in sequential manner. This

limitation of Von Neumann Computer is known as Von Neumann bottleneck. EDVAC

(Electronic Discrete Variable Automatic Computer) was the first stored program

computer developed in 1952.

G) Compare the salient features of first and second generation computers.

Answer:

Salient features of First generation computers:

Y Used vacuum tubes to control and amplify electronic signals

Y Huge computers that occupied lot of space (ENIAC weighed about 27 tons, was of the size 8 feet * 100 feet * 3 feet )

Y High electricity consumption (consumed around 150 watts of power) and high heat generation

Y Were unreliable since they were prone to frequent hardware failures

Y Commercial production was difficult

Y They were very costly and required constant maintenance

Y Continuous air conditioning was required

Y Programming was done in machine language although assembly language also

started at the end of this generation Example : ENIAC , EDVAC , UNIVAC 1

Salient Features of Second generation computers:

Y Use transistor based technology

Y Were smaller and less expensive as compared to first generation

Y Consumed less electricity and emitted less heat

Y Magnetic core memories and magnetic disks were used as primary and

secondary storage respectively

Y First operating system developed

Y Programming in assembly language and in the later part high level languages

were used

Y Wider commercial use but commercial production was still difficult

Y They also required constant air-conditioning.

Examples: IBM 1401, IBM 1620, UNIVAC 1108

H) Why is Charles Babbage known as the Father of Modern Computers?

Answer:

In 1833 Charles Babbage designed the Analytical Engine which later on proved to be the

basis of modern computer. His machine called basis of modern computer due to below features.

1. This machine could perform all the four arithmetic operations as well as comparison

2. It included the concept of central processor, memory storage and input-output devices.

3. Stored information could be modified.

I) Explain the functional components of a computer with the help of a block diagram.

Answer:

Input Unit

The input unit consists of input devices that are attached to the computer. These devices

take input and convert it into binary language that the computer understands. Some of

the common input devices are keyboard, mouse, joystick, scanner etc.

Central Processing Unit (CPU)

Once the information is entered into the computer by the input device, the processor

processes it. The CPU is called the brain of the computer because it is the control centre

of the computer. As the CPU is located on a small chip, it is also called the

microprocessor.

 It first fetches instructions from memory and then interprets them so as

to know what is to be done. If required, data is fetched from memory or input device.

Thereafter CPU executes or performs the required computation and then either stores

the output or displays on the output device.

The CPU has three main components which are responsible for different functions – 1. 1. Arithmetic Logic Unit (ALU) ,

2. Control

3. Unit (CU) and Memory registers.

Arithmetic and Logic Unit (ALU)

The ALU, as its name suggests performs mathematical calculations and takes logical

decisions. Arithmetic calculations include addition, subtraction, multiplication and

division.

Logical decisions involve comparison of two data items to see which one is

larger or smaller or equal.

Control Unit

The Control unit coordinates and controls the data flow in and out of CPU and also

controls all the operations of ALU, memory registers and also input/output units.

It is also responsible for carrying out all the instructions stored in the program. It decodes the fetched instruction, interprets (understands) it and sends control signals to

input/output devices until the required operation is done properly by ALU and

memory.

Memory Registers

A register is a temporary unit of memory in the CPU. These receive data/information

and then this data/information is held in them as per the requirement. Registers can be

of different sizes(16 bit , 32 bit , 64 bit and so on) and each register inside the CPU has a

1 4

specific function like storing data, storing an instruction, storing address of a location in

memory etc. The user registers can be used by an assembly language programmer for

storing operands, intermediate results etc. Accumulator (ACC) is the main register in

the ALU and contains one of the operands of an operation to be performed in the ALU.

Memory

Memory attached to the CPU is used for storage of data and instructions and is called

internal memory.

During processing, it is the internal memory that holds the data.

 The internal memory is divided into many storage locations, each of which can store data or instructions. Each memory location is of the same size and has an address. With the help of the address, the computer can find any data easily without having to search the entire memory.

The internal memory is also called the Primary memory or Main

memory. When the task is performed, the CU makes the space available for storing data

and instructions, thereafter the memory is cleared and the memory space is then

available for the next task. Therefore this memory is also called Random Access memory (RAM).

Primary memory is volatile in nature. That means when the power is switched off, the data stored in this memory is permanently erased. That is why secondary memory is needed to store data and information permanently for later use. Some of the examples of secondary storage devices are hard disk, compact disks, pen drives etc.

Output Unit

The output unit consists of output devices that are attached with the computer. It

converts the binary data coming from CPU to human understandable from. The

common output devices are monitor, printer, plotter etc.

J) What are the functions of the control unit?

Answer:

Control Unit

The Control unit coordinates and controls the data flow in and out of CPU and also

controls all the operations of ALU, memory registers and also input/output units.

 It is also responsible for carrying out all the instructions stored in the program.

It decodes the fetched instruction, interprets (understands) it .

It sends control signals to input/output devices until the required operation is done properly by ALU and

K) Where are the instructions needed to start a computer stored?

Answer:

I will answer this later.

L) Explain booting process and its types.

Answer:

When the computer is switched on, a copy of boot program is brought from ROM into

the main memory. This process is called booting. When the computer is switched on, a copy of boot program is brought from ROM into the main memory. This process is called booting.

The CPU first runs a jump instruction

that transfers to BIOS (Basic Input output System) and it starts executing. The BIOS

conducts a series of self diagnostic tests called POST (Power On Self Test). These tests

include memory tests, configuring and starting video circuitry, configuring the system’s

hardware and checking other devices that help to function the computer properly.

BIOS locates a bootable drive to load the boot sector. The execution is

then transferred to the Boot Strap Loader program on the boot sector which loads and

executes the operating system. If the boot sector is on the hard drive then it will have a

Master Boot record (MBR) which checks the partition table for active partition. If found,

the MBR loads that partition’s boot sector and executes it.

Cold Booting: When the system starts from initial state i.e. it is switched on, we call it

cold booting or Hard Booting. When the user presses the Power button, the instructions

are read from the ROM to initiate the booting process.

Warm Booting: When the system restarts or when Reset button is pressed, we call it

Warm Booting or Soft Booting. The system does not start from initial state and so all

diagnostic tests need not be carried out in this case. There are chances of data loss and

system damage as the data might not have been stored properly.

M) Differentiate between:
i) Digital computers and analog computers.

Answer:

Digital computers	Analog computers.
These computers are capable of processing information in discrete form	A computer which uses the continuous signal for its operation is called an Analog computer.
data which can be in the form of letters, symbols or numbers is represented in binary form i.e. 0s and 1s.	These computers measure changes in continuous physical quantities say current and voltage.
It computes by counting and Adding operations.	it is used to process data generated by changing physical quantities especially when the response to change is fast.
It work fast	It is slow
More accurate	Less accurate
The digital computers are used in industrial, business and scientific Applications. They are quite suitable for large volume data processing.	Some of the common examples where Analog computers are used simulations in aircrafts, nuclear power plants, hydraulic and electronic networks.

ii) Microcomputers and Mini Computers

Answer:

Microcomputers	Mini Computers
These are also known as Personal Computers. Ex desktops and laptops.	These computers can support multiple users working simultaneously on the same Machine.
These computers can work on small volume of data, are very versatile and can handle variety of applications.	These are mainly used in an organization where computers installed in Various departments are interconnected.
Consists of one processor.	Generally consists of multiprocessors.
Inexpensive and easy to use.	It can handle a huge amount of data.