Question 1

Question 1Assertion. A computer can deliver performance only through an efficient combination of hardware and software.Reason. While hardware refers to the physical electronics equipment, software are the recorded programs that govern the hardware to perform tasks in a computer.

Accepted Answer

(a)Both Assertion and Reason are true and Reason is the correct explanation of Assertion.ExplanationIf the hardware is inefficient, the best optimized software will also perform poorly on it and a poor software can degrade the performance of the best most efficient hardware. Hence, both need to be efficient for the computer to deliver best performance.

Question 2

Question 2Assertion. The CPU of a computer uses registers as memory.Reason. Registers are small data holding areas within CPU that hold data, instructions etc. during the processing.

Accepted Answer

(a)Both Assertion and Reason are true and Reason is the correct explanation of Assertion.ExplanationThe CPU uses registers to temporarily hold some important information during the time the processing is taking place.

Question 3

Question 3Assertion. The primary memory is volatile memory as all its contents get erased as soon as the power goes off.Reason. The cache memory is also a primary memory.

Accepted Answer

(b)Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.ExplanationPrimary memory is temporary as it is lost when power goes off. Cache memory is also temporary.

Question 4

Question 4Assertion. A part of main memory is non-volatile too.Reason. ROM is a read only memory with some pre-written instructions, which are retained even after power is off.

Accepted Answer

(a)Both Assertion and Reason are true and Reason is the correct explanation of Assertion.ExplanationROM is the non-volatile part of the main memory.

Question 5

Question 5Assertion. Not all types of software are system software.Reason. Application software are designed to carry out operations for a specific application.

Accepted Answer

(b)Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.ExplanationThe classification of Software into categories and sub-categories is as follows:System SoftwareOperating SystemLanguage ProcessorApplication SoftwarePackagesUtilitiesCustomised SoftwareDeveloper Tools

Question 6

Question 6Assertion. An operating system is a system software.Reason. The software that controls internal computer operations, is called system software.

Accepted Answer

(a)Both Assertion and Reason are true and Reason is the correct explanation of Assertion.ExplanationAn operating system controls all other components of a computer system and acts as an interface between a user and the hardware.

Question 7

Question 7Assertion. Customised software is a tailor made software according to user's requirements.Reason. Software libraries are customised software.

Accepted Answer

(c)Assertion is true but Reason is false.ExplanationSoftware libraries are not customised software. Software libraries are set of pre-written code/functions/classes etc. available to programmers for use in the development of new code.

Question 8

Question 8Assertion. Utility software programs are application software.Reason. Application software are the programs necessary to carry out operations for specific applications.

Accepted Answer

(a)Both Assertion and Reason are true and Reason is the correct explanation of Assertion.ExplanationUtility software are those application programs that assist the computer by performing housekeeping functions like backing up disk or scanning / cleaning viruses or arranging information, etc.

Question 9

Question 1Briefly explain the basic architecture of a computer.

Accepted Answer

A computer system comprises of five basic components:Input Unit — An input unit takes the input and converts it into binary form so that it can be understood by the computer. For example, keyboard, mouse etc.Output Unit — It converts the output in binary form to human readable form. For example, monitor, speakers etc.Central Processing Unit (CPU) — It is responsible for processing the data and instructions. It consists of two parts:Arithmetic and Logic Unit (ALU) — It performs all the four arithmetic operations (addition, subtraction, multiplication and division) and some logical operations (less than, greater than, less than equal to, greater than equal to, equal to, not equal to).Control Unit (CU) — It acts as a supervisor by controlling	and	guiding the operation taking place.Primary Memory — It is the internal volatile­ memory where data and instructions are stored during processing. It is of two types: Random Access Memory (RAM) and Read Only Memory (ROM).Secondary Storage Unit — It refers to the external storage devices which provide permanent memory to the computer system. For example, hard disk, compact disk, flash drive etc.

Question 10

Question 2What do you understand by input unit? What is its significance ? What does computer input consist of?

Accepted Answer

An input unit takes the input and converts it into binary form so that it can be understood by the computer.Since a computer operates on electricity, it can understand only the language of electricity i.e., either ON or OFF or High/Low voltage or the binary language that uses just two symbols: 1 for ON and 0 for OFF. It cannot understand the the data and instructions if they are not in binary language. Thus, input unit takes data and instructions from the user and converts them into binary form so that the computer can understand them.Different input devices take input in different forms and pass them in digital form to CPU for processing. Computer inputs may consist of:letters, digits, commands from the keyboard.movement of pointer using a mouse or pointing device.sound input from a microphone.

Question 11

Question 3What is the function of CPU in a computer system ? What are its subunits ?

Accepted Answer

The CPU or the Central Processing Unit is the main control centre and processing unit. It is also called brain of the computer as it guides, directs, controls and governs the performance of a computer.The CPU has three sub-components which are as follows:Arithmetic and Logic Unit (ALU) — It is responsible for carrying out the arithmetic instructions (add, subtract, multiply, divide) and making logic decisions (greater than, less than, equal to).Control Unit — It is responsible for controlling and supervising the processing.Registers — The CPU uses these small units of data holding places to temporarily hold some important processing-information during the time the processing is taking place.

Question 12

Question 4What functions are performed by the control unit ? Can we call it the control centre of computer system ? Why ?

Accepted Answer

Control Unit is responsible for controlling and supervising the processing. It performs the following functions:It controls and guides the interpretation, flow and manipulation of all data and information.It sends control signals until the required operations are done properly by ALU and memory.It fetches the program instructions from the memory unit one by one. The instructions are decoded and executed one after the other.After an instruction is executed, it sends a signal to memory to send the next instruction in sequence to CU.It controls the flow of data from input devices to memory and from memory to output devices.Yes, we can call control unit the control centre of computer system because it acts as a supervisor by controlling and	guiding all the other components of the computer system as well as the operations taking place.

Question 13

Question 5What functions are performed by the ALU ? Is it an independent unit ? If not, which unit does ALU work in coordination with ?

Accepted Answer

Arithmetic and Logic unit is responsible for carrying out the arithmetic instructions (add, subtract, multiply, divide) and making logic decisions (greater than, less than, equal to).No, it is not an independent unit. It is a part of CPU. It works in coordination with the commands given by the Control Unit.

Question 14

Question 6Distinguish between CPU and ALU.

Accepted Answer

CPUALUCPU refers to Central Processing Unit.ALU refers to Arithmetic and Logic unit.CPU is one of the main components of a computer system.ALU is a sub-unit of the CPU.CPU guides, directs, controls and governs the performance of a computer.ALU carries out arithmetic and logic operations on the operands in computer instructions.

Question 15

Question 7What is the function of output unit in a computer system ? Give examples of some output devices.

Accepted Answer

Output Unit converts the output in binary form to human readable form. The output coming from the CPU is in the form of binary signals which needs conversion in some human readable form i.e,, characters, graphical or audio visual form. This function of conversion is performed by output units.Examples of some output devices are monitor, speaker, printers, plotters etc.

Question 16

Question 8What role does memory play in the functioning of computer system ?

Accepted Answer

The memory of a computer is more like a predefined working place, where it temporarily keeps information and data to facilitate its performance. When the task is performed, it clears its memory and memory space is then available for the next task to be performed.There are two types of main memory:Random Access MemoryRead Only MemorySince computer's main memory is temporary, secondary memory space, such as hard disk, CDs, pen drive etc., is needed to store data and information permanently for later use.

Question 17

Question 9(a)Define byte.

Accepted Answer

A bit is an elementary unit of the memory. Eight bits together form a byte.

Question 18

Question 9(b)Define kilobyte.

Accepted Answer

A kilobyte is equal to 210 bytes i.e., 1024 bytes.

Question 19

Question 9(c)Define megabyte.

Accepted Answer

A megabyte is equal to 210 kilobytes i.e., 1024 kilobytes.

Question 20

Question 9(d)Define gigabyte.

Accepted Answer

A gigabyte is equal to 210 megabytes i.e., 1024 megabytes.

Computer System Overview

Assertions and Reasons

Assignment Questions

Checkpoint 1.1

Checkpoint 1.2

Checkpoint 1.3

Fill in the Blanks

Multiple Choice Questions

True/False Questions