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Solutions for Computer Science, Class 11, CBSE
Assertion. 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.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
If 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.
Assertion. 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.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
The CPU uses registers to temporarily hold some important information during the time the processing is taking place.
Assertion. 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.
(b)
Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
Explanation
Primary memory is temporary as it is lost when power goes off. Cache memory is also temporary.
Assertion. 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.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
ROM is the non-volatile part of the main memory.
Assertion. Not all types of software are system software.
Reason. Application software are designed to carry out operations for a specific application.
(b)
Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
Explanation
The classification of Software into categories and sub-categories is as follows:
Assertion. An operating system is a system software.
Reason. The software that controls internal computer operations, is called system software.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
An operating system controls all other components of a computer system and acts as an interface between a user and the hardware.
Assertion. Customised software is a tailor made software according to user's requirements.
Reason. Software libraries are customised software.
(c)
Assertion is true but Reason is false.
Explanation
Software 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.
Assertion. Utility software programs are application software.
Reason. Application software are the programs necessary to carry out operations for specific applications.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
Utility 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.
Briefly explain the basic architecture of a computer.
A computer system comprises of five basic components:
What do you understand by input unit? What is its significance ? What does computer input consist of?
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:
What is the function of CPU in a computer system ? What are its subunits ?
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:
What functions are performed by the control unit ? Can we call it the control centre of computer system ? Why ?
Control Unit is responsible for controlling and supervising the processing. It performs the following functions:
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.
What functions are performed by the ALU ? Is it an independent unit ? If not, which unit does ALU work in coordination with ?
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.
Distinguish between CPU and ALU.
CPU | ALU |
---|---|
CPU 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. |
What is the function of output unit in a computer system ? Give examples of some output devices.
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.
What role does memory play in the functioning of computer system ?
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:
Since 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.
Define byte.
A bit is an elementary unit of the memory. Eight bits together form a byte.
Define kilobyte.
A kilobyte is equal to 210 bytes i.e., 1024 bytes.
Define megabyte.
A megabyte is equal to 210 kilobytes i.e., 1024 kilobytes.
Define gigabyte.
A gigabyte is equal to 210 megabytes i.e., 1024 megabytes.
Define terabyte.
A terabyte is equal to 210 gigabytes i.e., 1024 gigabytes.
What is the meaning of the term volatile primary memory ? What can be done to overcome the problems of volatility ?
Volatile primary memory means that when the power goes off, the contents of the primary memory get erased.
Since computer's primary memory is volatile or temporary, secondary memory space is used to store data and information permanently for later use. Secondary storage media are the hard disk, CD-RWs, pen drive etc.
Distinguish between internal and external memory.
Internal memory | External memory |
---|---|
Internal memory is also known as primary storage or main memory. | External memory is also known as secondary storage. |
It is volatile in nature in case of RAM but ROM is non-volatile. | It is non-volatile in nature. |
It is used to store data temporarily (in case of RAM). | It is used to store data permanently. |
Internal memory is a working memory. | External memory is not a working memory. |
Examples are RAM and ROM. | Examples are hard disk, CD, DVD, flash drive etc. |
What is the role of memory in a computer functioning ? What types of memory does the computer work with?
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.
The computer works with two types of main memory:
Since the main memory is volatile, the computer also uses secondary memory to store data permanently.
What are RAM and ROM ? How are they alike ? How are they different ? What are EEPROM, PROM and EPROM?
RAM refers to Random Access Memory where both read and write operations can take place. But the RAM is a volatile memory and its contents are lost when power is turned off.
ROM refers to Read Only Memory where only read operation can take place. It does not have a write capability. ROM is a non-volatile memory.
RAM and ROM are the main memory of a computer and both of them are required for the smooth functioning of a computer system.
The RAM provides memory for reading as well writing and its contents can be modified as and when required. ROM, on the other hand, stores some instructions which are permanent. ROM cannot be written onto. One can only read instructions from ROM.
EEPROM refers to electrically erasable programmable ROM. In EEPROM, the EPROM is erased electrically which is faster. Also, with EEPROM, selective bytes can be erased unlike UV-EPROM which erases fully.
PROM refers to programmable ROM. It is a user-programmable memory in which information is burnt using special equipment called a ROM burner. It can be programmed only once.
EPROM refers to erasable programmable ROM. In EPROM, one can program the memory chip through various mechanisms (e.g., UV radiation) and erase it as many times as needed. The UV-EPROM can take up to 20 minutes for erasing EPROM contents.
What is cache memory ? How is it useful ?
The cache memory is a high speed memory available inside CPU in order to speed up access to data and instructions stored in RAM memory. Whenever some data is required, the CPU first looks in the cache, if it is there or not. If the data is found in cache, CPU does not access memory and hence the process becomes very fast.
Memory caching is effective because most programs access the same data or instructions over and over. By keeping as much of this information as possible in cache memory (SRAM), the computer avoids accessing the slower main memory (DRAM). Hence, cache memory is useful for improving the performance of the computer.
What are major functional components of a mobile system ?
The major functional components of a mobile system are as follows:
Draw a block diagram depicting organization of a mobile system.
Block diagram depicting mobile system organization is shown below:
What is the role of power management unit in a mobile system ?
The Power Management Subsystem is responsible for providing power to a mobile system. The mobile systems work on limited power provided through an attached battery unit. This subsystem has a battery management system that works with a battery charger and a battery unit, and provides power to the mobile system in required form.
What does the communication processor do ?
Communication processor of a mobile system is responsible for making and receiving phone calls on a mobile handset. It has a digital signal processor that helps it work with RF Transceiver and the Audio subsystem. Radio Signal Management Unit is responsible for connecting SIM to the base stations through radio signals.
What is the role of application processing unit in a mobile system ?
Applications Processing Unit (APU) is responsible for governing and controlling all types of operations taking place on a mobile system by running various types of mobile applications (apps).
How does display subsystem of a mobile system work ?
Display subsystem is responsible for providing display facilities, touch sensitive interface and touch sensitive keyboards.
What are different categories of software ? Give examples.
There are broadly two categories of software:
What is system software ? What role does it play in the functioning of the computer ?
The software that controls internal computer operations such as reading data from input devices, transmitting processed information to the output devices, checking system components, converting data/instructions to computer understandable form etc., is called System Software.
The system software can further be classified into two categories:
Discuss the role of utility software in the context of computer performance.
Utilities are those application programs that assist the computer by performing housekeeping functions like backing up disk or scanning / cleaning viruses or arranging information etc.
Utilities bridge the gaps by helping to solve the problems and maximize our computer's potential. Some important utilities are as follows:
What is the importance of an OS ?
An Operating System is a program which acts as an interface between a user and the hardware. For example, Microsoft Windows 10, Linux etc.
The primary goal of an operating system is to make the computer system convenient to use and secondary goal is to use computer hardware in an efficient manner. It performs the following functions:
How are software libraries useful ? Name some software libraries of Python.
Software libraries provide pre-written and tested code for a specific set of functions or features that can be included in a software program, saving programmers time and effort. By utilizing existing libraries, programmers can avoid having to write complex code from scratch and can benefit from the experience and knowledge of other developers who have contributed to the library. This results in more efficient coding, faster development, and more reliable software.
Some software libraries of Python are as follows:
How is system software different from application software ?
System Software | Application Software |
---|---|
It is designed to control the operations of a computer system. | It is designed to carry out specific tasks such as creating documents etc. |
These programs help in the running of other softwares. | These programs allow a computer to perform useful tasks beyond the running of the system itself. |
For example - Windows 10 | For example - MS Word |
What is the utility of disk defragmenter software ?
A file is fragmented when it becomes too large for our computer to store in a single location on a disk. When this happens, our computer splits the file up and stores it in pieces. We can use fragmented files, but it takes our computer longer to access them.
Disk Defragmenter utility program speeds up disk access by rearranging the files and free space on our computer, so that files are stored in contiguous units and free space is consolidated in one contiguous block.
What is the utility of backup software ?
Backup utility program facilitates the backing-up of disk. Back-up means duplicating the disk information so that in case of any damage or data-loss, this backed up data may be used.
To run your computer system, what types of software are necessary ? What role does each type play in computer's functioning ?
To run our computer system, the following two types of software are necessary:
Storage of 1 KB means the following number of bytes :
1024
Reason — 1 KB = 1024 bytes
One Megabyte is equivalent to
None of the above
Reason — 1 MB = 1024 KB = 1024 * 1024 bytes = 10,48,576 bytes.
What are the functional components of a digital computer ?
The functional components of a digital computer are as follows:
What are the components of CPU? What is its role? What is the function of control unit of CPU?
Central Processing unit is responsible for processing the data and instructions. It has the following sub-components:
What role does the input unit play in a computer?
An input unit takes the input and converts it into binary form so that it can be understood by the computer.
The input unit is formed by the input devices attached to the computer. For example, keyboard, mouse, magnetic ink character reader (MICR), optical mark reader (OMR), optical character reader (OCR), joystick, etc.
What is the function of ALU ?
The ALU performs the following functions:
What role does the output unit play in a computer?
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.
For example, monitor, speaker etc.
What is the function of main memory ? What are the measuring units of memory ?
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.
A bit is an elementary unit of the memory. The smallest unit of memory is a byte (8 bits). A byte can store one character in binary form. Other measuring units are kilobyte (KB) equal to 1024 (210) bytes, Megabyte (MB) equal to 1024 KB, Gigabyte (GB) equal to 1024 MB and Terabyte (TB) equal to 1024 GB.
What are different types of ROM ?
The different types of ROM are:
What is the role of cache memory ?
The Cache Memory is a high speed memory available inside CPU in order to speed up access to data and instructions stored in RAM memory. Whenever some data is required, the CPU first looks in the cache, if it is there or not. If the data is found in cache, CPU does not access memory and hence the process becomes very fast.
Which storage device is considered a portable device ?
A flash memory device is considered a portable device.
What are major functional components of a mobile system ?
The major functional components of a mobile system are as follows:
What is the role of communication processor of a mobile system ?
Communication processor of a mobile system is responsible for making and receiving phone calls on a mobile handset. It has a digital signal processor that helps it work with RF Transceiver and the Audio subsystem.
How does a mobile system manage and draw power?
The Power Management Subsystem is responsible for providing power to a mobile system. The mobile systems work on limited power provided through an attached battery unit. This subsystem has a battery management system that works with a battery charger and a battery unit, and provides power to the mobile system in required form.
What is the role of display management unit of a mobile system ?
The display management unit of a mobile system is responsible for providing display facilities, touch sensitive interface and touch sensitive keyboards.
How does memory of mobile function ?
A mobile system's memory is comprised of following two types of memories:
How does the CPU of a mobile system work?
A mobile system has to cater to a variety of operations and applications and its CPU has to manage all these. Thus the CPU of a mobile system has many sub-processors that help it control and manage diverse applications. The CPU of a mobile manages all these types of applications and operations:
How can computer software be classified ?
Computer software can be classified into two categories:
What are two categories of system software ?
Two categories of system software are as follows:
What is an operating system ? What is its role ?
An Operating System is a program which acts as an interface between a user and the hardware. For example, Microsoft Windows 10.
The primary goal of an operating system is to make the computer system convenient to use and secondary goal is to use computer hardware in an efficient manner. It controls all other components of the computer system and coordinates the use of the hardware among the various application programs for the various users.
What is application software ? What are the three categories of application software ?
An Application Software is the set of programs necessary to carry out operations for a specified application. These are the programs written by programmers to enable computer to perform a specific task such as processing words, inventory control, handling calculations and figures etc. For example, Microsoft Word 2013.
The three categories of application software are as follows:
Differentiate between a compiler and interpreter.
Compiler | Interpreter |
---|---|
A compiler converts an high level language program in machine language in one go. | An interpreter converts an high level language program into machine language line by line and simultaneously executes the converted line. |
If there are errors in the program, it gives the error list along with the line numbers. | If an error occurs in a line, the line is displayed and interpreter does not proceed unless the error is rectified. |
Once the errors are removed, error-free object code is made available and after this compiler is no more needed in the memory. | An interpreter must always be present in the memory along with the program for its execution. |
What is utility software ?
Utility programs assist the computer in maintaining its performance. Some of the utilities are text editors, backup utilities, compression utilities, disk defragmenters, and antivirus software.
What are software libraries? How are they useful to programmers ?
A software library is a predefined and available to use, suite of data and programming code in the form of pre-written code/functions/scripts/classes etc., that can be used in the development of new software programs and applications.
Software libraries provide pre-written and tested code for a specific set of functions or features that can be included in a software program, saving programmers time and effort. By utilizing existing libraries, programmers can avoid having to write complex code from scratch and can benefit from the experience and knowledge of other developers who have contributed to the library. This results in more efficient coding, faster development, and more reliable software.
Computer organisation refers to the logical structure of a computer describing their interconnections and dependency.
RAM and ROM are the types of internal/primary/main memory.
The Arithmetic and Logic Unit (ALU) is responsible for carrying out arithmetic and logic operations.
The Control Unit (CU) of the CPU controls or supervises the processing taking places.
The small memory providing units inside the CPU are called the registers.
The cache memory is a special high speed memory storing the most recently accessed data.
The power unit of a mobile system is called battery.
The set of programs necessary to carry out operations/tasks pertaining to a specific application, are called application software.
Software that controls and manages internal computer operations is called system software.
Utility programs are a type of application software.
Antivirus software is a type of application software.
Windows OS is a type of system software.
Which of the following components is the main memory of computer ?
RAM
Reason — RAM is the main memory of the computer.
Which component of a computer connects the processor to the other hardware?
System Bus
Reason — The system bus is an electronic pathway composed of connecting cables that connects the major components of a computer system.
Which of the following is referred to the brain of computer ?
Processor
Reason — Processor or CPU is called brain of the computer as it guides, directs, controls and governs the performance of a computer.
What is the name of programs that control the computer system ?
Software
Reason — Software is a set of programs that govern the operation of a computer system.
The physical components of a computer are called ?
Hardware
Reason — Hardware are all the parts of the computer you can see and touch.
Which of the following is the common measurement of unit of computer memory?
Terabyte, Gigabyte
Reason — Terabyte and Gigabyte are the common measurement of unit of computer memory.
What is the name of the component that is used to both read and write data ?
RAM
Reason — RAM is used to both read and write data.
The CPU is also known as :
All of these
Reason — The CPU is also known as the brain of the computer, the processor and the Central Processing Unit.
Which smaller unit of the CPU directs and coordinates all activities within it and determines the sequence in which instructions are executed, sending instructions sequence to other smaller unit.
CU
Reason — Control unit coordinates all activities within it and determines the sequence in which instructions are executed, sending instructions sequence to other smaller unit.
Which smaller unit of the CPU performs all arithmetic and logic functions in a computer ?
ALU
Reason — Arithmetic and Logic Unit performs all arithmetic and logic functions in a computer.
Component of CPU which is responsible for comparing the contents of two pieces of data is ............... .
ALU
Reason — Arithmetic and Logic Unit is responsible for comparing the contents of two pieces of data.
In a computer, CU stands for
control unit
Reason — In a computer, CU stands for control unit.
Arithmetic and logic unit along with control unit of a computer, combined into a single unit, is known as ............... .
central processing unit
Reason — Arithmetic and logic unit along with control unit of a computer, combined into a single unit, is known as central processing unit.
Word Processor and Desktop Publishing program are the examples of ............... .
software
Reason — Word Processor and Desktop Publishing program are the examples of software.
Operating System is an example of ............... .
System software
Reason — Operating System is an example of System software.
A disk fragmentor is an example of ............... .
Application Software / Utility program
Reason — A disk fragmentor is an example of utility program. Since utility program is a sub-category of application software, hence it is classified as an application software as well.
Flash memory and Blu Ray disk are the examples of ............... .
Hardware
Reason — Flash memory and Blu Ray disk are the examples of hardware.
Flash memory is a type of ............... memory.
secondary
Reason — Flash memory is a type of secondary memory.
Which of the following memory types will store the data or information permanently?
Flash Memory, Hard disk
Reason — Flash Memory and Hard disk are external storage devices and hence they will store the data or information permanently.
Which of the following memory types cannot store the data or information permanently ?
RAM
Reason — RAM is a volatile memory and loses all its data when the power is turned off.
A computer system consists of both hardware and software.
True
Hardware is a set of instructions called programs that the computer uses to carry out tasks while Software are all the parts of the computer you can see and touch, also known as peripherals.
False
The two smaller units of the Processor are CU and ALU.
True
Main Memory holds data and instructions being processed by the computer and is directly accessible by the CPU.
True
A mobile system also contains a CPU.
True
A mobile system works with electricity.
False
A mobile system has its own little power unit.
True
A cache memory is a type of RAM.
True
Language processors are a type of application software.
False
Customised software is a type of system software.
False