Looking for accurate SEBA Class 9 Computer Science Chapter 1 (Introduction to Computer System) textual solutions for the 2026–27 academic year? Access complete step-by-step solutions covering computer architecture, hardware vs. software, primary and secondary memory, input/output devices, CPU components, and data representation to score top marks in your annual exams.
Choose the correct option.
(a) Which of the following is not an output device?
(1) Speaker
(2) Mouse
(3) Printer
(4) Monitor
Ans: (2) Mouse.
(b) Which one of the following is the “brain” of a computer?
(1) CPU
(2) ALU
(3) CU
(4) MU
Ans: (1) CPU.
(c) A collection of eight bits is called______.
(1) Byte
(2) Word
(3) Record
(4) Nibble
Ans: (1) Byte.
(d) Second-generation computers were manufactured using which technology?
(1) Vacuum Tubes
(2) Transistors
(3) ICs
(4) None of these
Ans: (2) Transistors.
(e) Storage of 1KB means the following number of bytes:
(1) 1000
(2) 1024
(3) 1064
(4) 1012
Ans: (2) 1024.
(f) Which of the following is not hardware?
(1) Hard disk
(2) Printer
(3) Assembler
(4) CPU
Ans: (3) Assembler.
(g) Fourth generation computers used
(1) Vacuum tubes
(2) Transistors
(3) Microprocessors
(4) ICs
Ans: (3) Microprocessors.
(h) Which one of the following is a special-purpose application software?
(1) word-processing software
(2) Compiler
(3) Operating system software
(4) Payroll system
Ans: (4) Payroll system.
(i) The base of the Octal Number System is _.
(1) 2
(2) 10
(3) 16
(4) 8
Ans: (4) 8.
(j) who is known as the father of the modern computer?
(1) Charles Babbage
(2) Herman Hollerith
(3) Blaise Pascal
(4) John Atanasoff
Ans: (1) Charles Babbage.
Fill in the blanks.
(a) The first-generation computers used______for storage.
Ans: magnetic tape.
(b) The third-generation computer replaced______with _.
Ans: transistors, Integrated Circuits (ICs)
(c) ______are high speed temporary storage area.
Ans: Registers.
(d) _____is the short form of binary digit.
Ans: Bit
(e) A group of four bits is called __.
Ans: Nibble.
(f) _____holds data , programs and instructions for computer.
Ans: RAM .
(g) A microphone is ____device.
Ans: input.
(h) A ____is set of instructions to perform a specific task.
Ans: program.
(i) _____software are used to scan the computers for viruses.
Ans: Antivirus.
(j) The decimal system is composed of __ digits.
Ans: 10.
(k) _____was the first fully electronic general-purpose computer.
Ans: ENIAC.
(l) ____was one of the first commercially available computers.
Ans: UNIVAC.
(m) An _____converts the program written in assembly language into machine language.
Ans: assembler.
(n) Processing takes place in the_____.
Ans: CPU.
(o) The ALU performs the ____and ____operations.
Ans: arithmetic, logical.
(p) RAM is or .
Ans: temporary, volatile.
(q) ROM stores basic _____instructions to operate the computer.
Ans: input / output.
(r) _____memory is an electronic non-volatile storage medium that can be electrically erased and reprogrammed.
Ans: EEPROM.
(s) Data and instructions are given to the computer through its ____device.
Ans: input.
(t) Raw data is processed by the computer to produce_____.
Ans: output.
(u) Results are obtained from the computer through its ____device.
Ans: output.
(v) 1 MB = __ KB.
Ans: 1024.
(w) ______is an example of primary memory.
Ans: RAM.
(x) The octal number system uses the digits from to.
Ans: 0,7.
(y) A computer system comprise of both _ and_.
Ans: hardware, software.
(z) _____represents the set of program that directs the computer how to work.
Ans: software.
State true or false.
(a) Another name for internal memory is primary memory.
Ans: TRUE.
(b) A hard disk can store less data than CD.
Ans: FALSE.
(c) software represents the physical components of a computer.
Ans: FALSE
(d) A projector is an input device.
Ans: FALSE.
(e) Interpreter is a utility software.
Ans: TRUE.
(f) The first-generation computers used transistors.
Ans: FALSE.
(g) Atanasoff Berry computer was the first electronic digital computer.
Ans: TRUE.
(h) IBM 604 is an example of second-generation computers.
Ans: TRUE.
(i) UNIVAC was one of the first commercially available computers.
Ans: TRUE.
(j) ROM is volatile.
Ans: FALSE.
(k) A group of eight bits is called nibble.
Ans: FALSE.
(l) Computers do not understand any language other than machine language.
Ans: TRUE.
(m) Pen drives use flash memory to store data.
Ans: TRUE.
(n) The monitor is a soft copy output device.
Ans: TRUE.
(o) A compiler translates a program written in machine language into a program written high level language.
Ans: TRUE.
(p) Bit is the smallest unit of data in a computer.
Ans: TRUE.
SEBA Class 9 Computer Science Chapter 1 Solutions
Short answer questions.
Q1. Who is known as the ‘father of the modern computer’?
Ans: Charles Babbage is known as the ‘father of the modern computer.
Q2. What is a computer?
Ans: A computer is an electronic device that accept data from the user, process the given data and generate the processed output.
Q3. Name a popular pointing device.
Ans: Mouse is a popular pointing device.
Q4. Who invented Jacquard’s loom?
Ans: Joseph Jacquard invented Jacquard loom.
Q5. Give the full from of ENIAC and EDVAC.
Ans: ENIAC – Electronic Numerical Integrator and computer
EDVAC – Electronic Discrete Variable Automatic Calculator.
Q6. Give two examples of second-generation computers.
Ans: IBM604, IBM1401, UNIVAC 1108
Q7. What is AI?
Ans: Artificial Intelligence (AI) is the science of creating machines that can think like humans. It can perform tasks that are considered “smart.” AI technology can handle and process large amounts of data in ways that humans cannot.
Q8. Give two examples of secondary memories.
Ans: Floppy disk Hard disk.
Q9. What does the CPU do?
Ans: A Central Processing Unit (CPU) reads, processes, and executes instructions, mainly from the hardware and software on a device.
The CPU carries out arithmetic, logic, and other operations to convert input data into useful output information.
Q10. Why do we use secondary memory?
Ans: We use secondary memory because it provides large storage, allowing us to store big data like videos, images, audio, and files permanently. Additionally, some secondary storage devices are portable, meaning they can be removed and used to transfer data between computers or devices easily.
Q11. Give two examples of pointing devices.
Ans: Mouse, and Trackball
Q12. Which input device is used to record sound?
Ans: Microphone is used to record sound
Q13. What is the use of a barcode reader?
Ans: A barcode reader is used to scan and read information stored in a barcode. A barcode represents data using machine-readable lines, allowing quick and accurate identification of products or items.
Q14. What is system software? Give two examples.
Ans: System software is a type of computer program designed to operate a computer’s hardware and support application programs.
Examples:
Operating System
& Encryption/Decryption Software
Q15. What is the role of CU?
Ans: The Control Unit (CU) is a part of the computer’s CPU that manages the processor’s operations. It gives instructions to the computer’s memory, arithmetic/logic unit, and input/output devices, telling them how to follow a program’s commands.
Q16. What is the function of ALU?
Ans: ALU is the Arithmetic and Logic Unit, which performs all arithmetic and logical operations such as addition, subtraction, logical AND, OR, etc.
Q17. What do you understand by memory word?
Ans: Computer memory is the storage space in a computer. The memory unit provides space for storing data and instructions, space for intermediate results, and also space for the final results.
Q18. What is the function of a Compiler?
Ans: A compiler is a special program that converts a programming language’s source code into machine code or bytecode. It translates code from a high-level programming language to a lower-level language. The source code is usually written in human-readable languages like Java or C++.
Q19. What is the main limitation of a computer?
Ans: The main limitations of a computer are:
i) A computer cannot function without instructions provided by humans.
ii) It cannot respond to a situation unless it has been pre-programmed for that specific scenario.
Q20. Mention three main features of a computer.
Ans: The main features of a computer are:
i) Speed: A computer operates at a very high speed.
ii) Accuracy: Computers perform calculations with 100% accuracy. Errors may happen due to incorrect or inconsistent data.
iii) Memory: A computer has built-in primary memory to store data
Q21. What is a computer program?
Ans: A computer program is a set of instructions that a computer can execute to complete a specific task. It is usually written by a programmer using a programming language.
Q22. What are the fundamental components of a computer system?
Ans: The fundamental components of a computer system are:
i) Storage device.
ii) Motherboard
iii) Central Processing Unit (CPU)
iv) Graphical Processing Unit (GPU)
v) Random Access Memory (RAM)
Q23. What is application software?
Ans: Application software is a type of computer program that performs a specific personal, educational, and business function.
Microsoft Word and Excel, as well as popular web browsers like Firefox and Google Chrome, are examples of application software.
Q24. Mention various categories of application software?
Ans: Application software can be divided into two categories:
The first is general software like word processors, web browsers, spreadsheet software, etc.
The second type of software is custom software customized according to the need of the user and their organizational needs.
Q25. What do you understand by computer memory?
Ans: Computer memory is the storage space in the computer. The memory unit provides space for storing data and instructions, space for intermediate results, and also space for the final results
Q26. What is the binary equivalent of hexadecimal 15 ?
Ans: (00010101)2
Class 9 Computer Science Chapter 1 Question Answer SEBA 2026-27
Long answer questions.
Q1. Mention four features of a computer system.
Ans: Four features of a computer system are:
i) Speed: A computer can perform millions of calculations in a short time, whereas a human would take much longer to complete the same task.
ii) Accuracy: Computers work very fast and accurately. They do not make mistakes in calculations, and any errors usually occur due to human input mistakes.
iii) Diligence: Unlike humans, computers do not get tired. They can work continuously for hours, days, or even months without losing efficiency.
iv) Storage: Computers can store a large amount of data, including images, videos, text, audio, and files, making it easy to access and manage information.
Q2. Mention the characteristics features of third-generation computers.
Ans: Characteristics of Third Generation Computers:
i) Less expensive maintenance cost.
ii) Use of Integrated Circuits (IC) instead of transistors
iii) Use of Semi-conductor memory
iv) Small size than previous generation computers
v) Use of magnetic storage devices
vi) Improved faster operations and more dependable output
vii) Use of mini computers
viii) Use of monitors and line printers
ix) Use of high-level programming languages
x) Less expensive than 2nd generation computers
Q3. What do you understand by generation of computers?
Ans: In computer terminology, generation refers to the change in technology used in computers. Initially, the term was used to differentiate between different hardware technologies. Today, it includes both hardware and software, which together form a complete computer system.
Q4. Mention two disadvantages of first – generation computers.
Ans: Disadvantages of First-Generation Computers:
i) Expensive commercial productio
ii) Very large in size.
iii) High energy consumption.
iv) Overheating due to thousands of vacuum tubes.
v) Not reliable.
vi) Required air conditioning.
vii) Needed constant maintenance.
viii) Not portable.
Q5. Describe the functioning of CPU.
Ans: The functions of the CPU are:
i) It also stores processed data in the form of a cache for future use.
ii) The CPU receives data when the computer inputs information through an input device like a keyboard or mouse
iii) It processes the input data by performing calculations and executing algorithms.
iv) The CPU provides the processed data through output devices, such as displaying results on a monitor.
Q6. Discus Draw a block diagram of a computer system.
Ans: A computer basically performs five major operations:
Controlling and coordinating all operations inside the computer For Diagram refer word
Accepting data or instructions
Processing data
Storing data
Displaying results
Q7. What are the categories of printers? Explain.
Ans: A printer is a hardware output device used to generate hard copies of documents, which can include text, images, or both.
It receives input commands from a computer or other devices to print documents.
Categories of Printers:
i) Impact Printers: These printers have physical contact between the print head and paper.
Impact printers are subdivided into line printers and character printers.
ii) Line Printers: Print one line of text at a time (e.g., Drum Printer, Chain Printer).
iii) Character Printers: Print one character at a time (e.g., Dot Matrix Printer, Letter-Quality Printer).
iv) Non-Impact Printers: These printers do not have physical contact between the print head and paper. They are faster than impact printers.
Examples: Inkjet Printer, Thermal Printer, Electromagnetic Printer, Laser Printer.
Q8. What is a bus? Explain three types of buses.
Ans: A bus is a subsystem used to connect computer components and transfer data between them.
There are three main types of buses:
i) Control Bus: Sends instructions between the CPU and other parts of the computer.
ii) Data Bus: Transfers data between the CPU and memory.
iii) Address Bus: Carries the memory address from the CPU to the memory.
Q9. What are the functions of a primary storage area?
Ans: i) Primary storage memory, also called main memory, is a very important part of a computer.
ii) It holds the data and instructions that the computer is using right now.
iii) This helps the computer work quickly because the processor (CPU) can get the needed information fast.
iv) There are two main types of primary memory: RAM and ROM. RAM (Random Access Memory) is used for temporary storage. It loses all the data when the computer is turned off. ROM (Read-Only Memory) stores important information that doesn’t change, like how to start the computer.
v) Primary memory is much faster than a hard drive, but it can only hold information while the computer is on. This memory helps the computer run smoothly and respond quickly to what the user is doing.
Q10. Explain three types of ROM.
Ans: The different types of ROM are:
i) EEPROM (Electrically Erasable Programmable Read-Only Memory): Can be programmed and erased electrically multiple times.
ii) PROM (Programmable Read-Only Memory): Can be programmed only once by a user and cannot be erased.
iii) EPROM (Erasable Programmable Read-Only Memory): Can be reprogrammed by erasing the stored data using ultraviolet light.
Q11. What is the purpose of a language processor? Explain the three language processors.
Ans: A language processor (or translator) is a program that converts source code from one programming language to another.
It also detects errors during translation. High-level programming languages like C++, Python, and Java require language processors for execution.
Types of Language Processors:
i) Compiler: Translates the entire high-level program at once into machine language.
Example: C, C++, C#
ii) Interpreter: Translates and executes the program line by line, immediately running each statement before moving to the next.
iii) Assembler: Converts programs written in Assembly language into machine code.
Q12. Difference between data and information.
| Data | Information |
| Raw, unorganized facts and figures (like numbers, symbols, or words). | Processed, organized, and meaningful data. |
| It does not have any clear context or direct meaning on its own. | It is meaningful, clear, and easy to understand. |
| Data is used as input for a computer system. | Information is obtained as output from a computer system. |
| It does not directly help in making decisions. | It helps users make decisions. |
| Examples: Marks obtained by a student ($85, 90, 78$), raw attendance numbers. | Examples: Report card, merit list, final class percentage. |
Q13. Write short notes on fifth-generation computers.
Ans: The fifth generation of computers started in 1980 and continues to the present. In this generation, ULSI (Ultra Large Scale Integration) technology replaced VLSI,
leading to microprocessor chips with millions of components. These computers use parallel processing and Artificial Intelligence (AI), enabling machines to think like humans.
High-level languages like C, C++, Java, and .Net are widely used.
Features of Fifth-Generation Computers:
i) Efficient mainframe computers for large-scale operations.
ii) Uses ULSI technology for better performance.
iii) Natural language processing has improved significantly.
iv) Advanced artificial intelligence capabilities.
v) Parallel processing for faster computations.
vi) More user-friendly interfaces and multimedia functions.
vii) Lower cost compared to previous generations.
viii) More portable and powerful computers.
ix) Reliable and affordable systems.
x) Easier commercial manufacturing.
xi) Simple to operate desktop computers.
Q14. What are the basic differences between the four generations of computers?
Ans: Basic Differences Between the First Four Generations of Computers:
Fourth Generation (1971–Present)
a) Used Microprocessors with millions of transistors on a single chip.
b) Personal computers (PCs) became widely available.
c) Graphical User Interfaces (GUI) and high-level languages like C, C++, and Java emerged.
First Generation (1940–1956)
a) Used vacuum tubes for processing.
b) Large, expensive, and consumed a lot of power.
c) Slow processing speed and frequent overheating.
Second Generation (1956–1963)
a) Used transistors instead of vacuum tubes.
b) Smaller, faster, and more reliable than first-generation computers.
c) Used assembly language for programming.
Third Generation (1964–1971)
a) Used Integrated Circuits (ICs) instead of transistors.
b) More efficient, smaller, and cheaper than second-generation computers.
c) Introduced keyboards and monitors for input and output.
Q15. Write a short note on MARK – I.
Ans: MARK I was designed in 1937 by Howard H. Aiken, a Harvard graduate student, to solve advanced mathematical physics problems in his research.
Aiken’s idea was to use modified commercial technologies, controlled by a central system, to perform complex calculations efficiently.
Q16. Explain the two main types of secondary memory.
Ans: Secondary memory refers to storage devices that are either built into the computer or externally connected.
It is also called external memory or auxiliary storage and is used to store data permanently.
Main Types of Secondary Memory:
i) Hard Disks – Primary storage for computers, offering large capacity and fast access
ii) Removable Storage Devices – Portable and convenient, including:
a) Pen Drive (USB Flash Drive)
b) SD Card
c) CD (Compact Disc)
d) DVD (Digital Versatile Disc)
Q17. Describe various types of magnetic media.
Ans: The various types of magnetic media are:
(1) Floppy disks: Flexible disks with a magnetic coating, capable of storing 1.44 MB of data.
(2) Hard disks: Non-volatile storage devices installed inside computers, directly connected to the motherboard.
(3) Magnetic taps: Used for large data storage, available in cassettes, reels, and cartridges.
(4) Zip Diskette: Used with a Zip drive, offering 100 MB or 250 MB of storage for backups and data sharing..
(5) Super Disk: Introduced by 3M (Imation), capable of storing 120 MB to 240 MB, similar in size to a floppy disk.
Q18. Mention some areas where computer are used widely.
Ans: Computers are used in almost every field today. Here are some key areas where computers are widely used:
1. Manufacturing and Engineering – Used in CAD, CAM, robotics, process automation, and quality control.
2. Personal Use – Commonly used for online shopping, social networking, entertainment, and daily tasks.
3. Business and Finance – Used for data analysis, accounting, inventory management, and online transactions.
4. Education – Helps in online learning, research, multimedia presentations, and administration
5. Communication – Used for email, video conferencing, social media, and instant messaging.
6. Healthcare – Supports medical records, diagnostic imaging, patient monitoring, and research.
7. Entertainment and Media – Used for video editing, animation, special effects, gaming, and streaming.
8. Transportation and Logistics – Helps in traffic control, airline reservations, GPS navigation, and supply chain management.
9. Science and Engineering – Essential for research, simulations, complex modeling, and data analysis.
10. Government and Administration – Supports record-keeping, public services, data management, and policy making.
Q19. What are the major operations performed by a computer?
Ans: The basic operations of a computer system include:
Controlling and coordinating – Manages all internal computer functions.
Accepting data or instructions – Receives input from users.
Processing data – Performs calculations and logical operations.
Storing data – Saves data for future use.
Displaying results – Outputs processed data as information.
Introduction to Computer System Class 9 SEBA Chapter 1 Solutions
Differentiate between the following pairs:
I. Input unit and Output unit
| Input Unit | Output Unit |
|---|---|
| Input is any data that is sent to the computer for processing. | Output is the result of processed data that we can see through some other devices. |
| Input devices are controlled by the users. | Output devices are controlled by computers. |
| It converts user-friendly instruction into machine-friendly. | It converts the machine’s instructions to the user’s readable language. |
| It takes the data from the user and sends it to the processor for execution. | It takes the processed data from the processor and sends it back to the user. |
| Mouse, Keyboards etc., are input device examples. | Monitors, Printers etc., are examples of output devices. |
II. RAM and ROM
| RAM | ROM |
|---|---|
| RAM stands for Random Access Memory. | ROM stands for Read Only Memory. |
| Random Access Memory (RAM) is costly if compared to ROM. | ROM is more inexpensive when compared to RAM. |
| The data saved in RAM is utilized by the Central Processing Unit (CPU) to prepare current instructions. | The data collected in ROM is applied to bootstrap the computer/PC. |
| It is a high-speed memory. | It is much slower than the RAM. |
| It is employed as CPU Cache, Primary Memory in a computer. | It is utilized as Firmware by micro-controllers. |
III. Soft copy and hard copy
| Hard Copy | Soft Copy |
| Hard copy is a printed document file. | Soft copy is a non-printed document file. |
| It is a physical copy. | It is a virtual copy. |
| Hard copies are physical paper copies. | Soft copies are electronically written copies. |
| Hard copy does not require an electronic interface like computers or mobiles etc. to read and display. | Soft copy requires an electronic interface like computers or mobiles etc. to read and display. |
| Hard copies are not easily portable like soft copy. | Soft copies are easily portable than hard copy. |
| These copies are mainly preferred in official works. | These copies are mainly preferred for private purposes. |
| Books, newspapers, magazines, etc. are examples. | PDF file, scanned copy, Word doc, presentation file, etc. are examples. |
IV. Primary memory and secondary memory
| Primary Memory | Secondary Memory |
|---|---|
| Primary memory is temporary. | Secondary memory is permanent. |
| Data stored in primary memory can be directly accessed by the CPU. | Data stored in secondary memory cannot be directly accessed by the CPU. |
| Primary memory is a semiconductor memory. | Secondary memories are magnetic and optical memories. |
| The speed of data accessing in the primary memory is faster. | The data accessing speed of the secondary memory is slower. |
| Primary memory is volatile, which means it is wiped out when the computer is turned off. | Secondary memory is non-volatile, meaning data is retained in case of a power failure. |
| Primary memory can be accessed by the data bus. | Secondary memory is accessed by I/O channels. |
| It is expensive in comparison to secondary memory. | It is less expensive in comparison to primary memory. |
| Examples: RAM, ROM, Cache memory, PROM, EPROM, Registers, etc. | Examples: Hard Disk, Floppy Disk, Magnetic Tapes, etc. |
V. Impact-printer and non-impact printer
| Impact Printer | Non-impact Printer |
|---|---|
| Impact printers create pictures and figures by hitting a device such as a wheel or a print hammer against an inked ribbon. | Non-impact printers create figures and pictures without any physical contact between the printing device and the paper. |
| Printing is done by hammering a set of metal pins or character sets. | Printing is done by depositing ink or toner particles. |
| Uses an inked ribbon. | Uses toner or ink cartridges. |
| Slower speeds (around 1 page per 30 seconds). | Faster speeds (around 250 words per second or higher). |
| Produces a distinct banging noise from the pin/hammer hitting paper. | Works silently. |
| Impact printers (other than dot matrix printers) generally cannot print graphic images. | Printing high-quality graphical images is very feasible. |
| Except for dot matrix printers, character styles cannot easily be changed. | Can print in various character styles and fonts. |
| They are cheap. | They are more expensive. |
VI. Assembler and Compiler
| Compiler | Assembler |
|---|---|
| Converts source code written in high-level language to machine-level language / mnemonic intermediate code. | Converts assembly code into machine-level code (binary). |
| Takes high-level programming language code as input. | Takes assembly language code as input. |
| Converts the entire source code into machine code at once. | Translates assembly code sequentially line by line or in passes into binary. |
| Output can be machine code or a mnemonic/object file. | Output is purely binary machine code ($0$s and $1$s). |
| More intelligent, complex, and handles advanced programming constructs. | Less complex, performing direct translation of assembly instructions. |
| Converts entire complex programs in one complete compilation process. | Cannot perform single-pass conversion for complex high-level programs. |
| Examples: Compilers for C, C++, Java, and C#. | Examples: GAS (GNU Assembler), NASM, MASM. |
VII. Hardware and software
| Hardware | Software |
| Hardware refers to the physical components of a computer that help to set up a computer system and execute instructions. | Software refers to the set of instructions that help users to interact with computer components and instruct the CPU to do the intended or specified tasks. |
| Tangible. We can see and touch the hardware. | Intangible. We can see but cannot touch software. |
| Hardware cannot perform any task without software. | Software cannot be executed without hardware. |
| Hardware is not affected by computer viruses. | Software is affected by computer viruses. |
| Storage Devices, Input Devices, Output Devices, and Internal components are the primary categories of hardware. | Operating Systems, Application Software, and Programming Software are the main categories of software. |
| A Hardware engineer physically builds hardware using electronic components. | Software is developed by software engineers using various programming languages. |
| We can replace the hardware with a new component if damaged or corrupted. | When damaged or corrupted, we can install the software again using a backup copy. |
| Examples: Keyboard, Mouse, Monitor, Printer, CPU, Hard disk, RAM, ROM, etc. | Examples: MS Word, MS Excel, MS PowerPoint, Photoshop, etc. |
VIII. System software and application software
| System Software | Application Software |
| Interface between application software and the underlying computer system. | Runs as per user request on the platform provided by system software. |
| Written using low-level languages (assembly or C). | Written using high-level languages (Java, C++, Python, etc.). |
| Runs independently and provides a platform for application software to execute. | Cannot run independently; requires system software to execute. |
| System software is essential—a computer system cannot operate without it. | A computer system can run without application software, though specific user tasks require it. |
| Classified into types like time-sharing, resource-sharing, and client-server systems. | Classified as package software or customized/bespoke programs. |
| It is general-purpose software designed to manage hardware and core functions. | It is specific-purpose software designed to perform specific user-facing tasks. |
| Examples: Operating Systems, Compilers, Assemblers, Debuggers, Device Drivers. | Examples: Word Processors, Web Browsers, Media Players, Spreadsheets. |
SEBA Class 9 Computer Science Ch 1 Textbook Answers
Carry out the following conversions:
a. Convert 135(10) to binary:
135 ÷ 2 = 67 r 1
67 ÷ 2 = 33 r 1
33 ÷ 2 = 16 r 1
16 ÷ 2 = 8 r 0
8 ÷ 2 = 4 r 0
4 ÷ 2 = 2 r 0
2 ÷ 2 = 1 r 0
1 ÷ 2 = 0 r 1
Answer: 135(10) = 10000111(2)
b. Convert 1100110(2) to decimal:
= 1×64 + 1×32 + 0×16 + 0×8 + 1×4 + 1×2 + 0×1 = 102
Answer: 1100110(2) = 102(10)
c. Convert 110.110(2) to decimal:
Integer: 1×4 + 1×2 + 0×1 = 6
Fraction: 1×0.5 + 1×0.25 + 0×0.125 = 0.75
Answer: 110.110(2) = 6.75(10)
d. Convert 35.375(10) to binary:
Integer part:
35 ÷ 2 = 17 r 1
17 ÷ 2 = 8 r 1
8 ÷ 2 = 4 r 0
4 ÷ 2 = 2 r 0
2 ÷ 2 = 1 r 0
1 ÷ 2 = 0 r 1 -> 100011
Fraction:
0.375 × 2 = 0.75 -> 0
0.75 × 2 = 1.5 -> 1
0.5 × 2 = 1.0 -> 1 -> .011
Answer: 35.375(10) = 100011.011(2)
e. Convert 265(10) to octal:
265 ÷ 8 = 33 r 1
33 ÷ 8 = 4 r 1
4 ÷ 8 = 0 r 4
Answer: 265(10) = 411(8)
f. Convert 250.375(10) to octal:
Integer part:
250 ÷ 8 = 31 r 2
31 ÷ 8 = 3 r 7
3 ÷ 8 = 0 r 3 -> 372
Fraction:
0.375 × 8 = 3.0 -> 3 -> .3
Answer: 250.375(10) = 372.3(8)
g. Convert 375(8) to decimal:
= 3×64 + 7×8 + 5×1 = 253
Answer: 375(8) = 253(10)
h. Convert 375(16) to decimal:
= 3×256 + 7×16 + 5 = 885
Answer: 375(16) = 885(10)
i. Convert 25.6(8) to decimal:
Integer: 2×8 + 5 = 21
Fraction: 6×(1/8) = 0.75
Answer: 25.6(8) = 21.75(10)
j. Convert 125(16) to decimal:
= 1×256 + 2×16 + 5 = 293
Answer: 125(16) = 293(10)
k. Convert 436(10) to hexadecimal:
436 ÷ 16 = 27 r 4
27 ÷ 16 = 1 r 11 -> B
1 ÷ 16 = 0 r 1
Answer: 436(10) = 1B4(16)
Class 9 Computer Science Basics Hardware Software Solutions
l. Convert 213.03125(10) to hexadecimal:
213 ÷ 16 = 13 r 5 -> D5
13 ÷ 16 = 0 r 13 -> D
Fraction:
0.03125 × 16 = 0.5 -> 0
0.5 × 16 = 8.0 -> 8 -> .08
Answer: 213.03125(10) = D5.08(16)
m. Convert 55.08(16) to decimal:
= 5×16 + 5 = 85
8/256 = 0.03125
Answer: 55.08(16) = 85.03125(10)
n. Convert 11001101111(2) to hexadecimal:
0001 1001 1011 1111 = 1 9 B F
Answer: 11001101111(2) = 19BF(16)
o. Convert 10011001.10111001(2) to hexadecimal:
Integer: 1001 1001 = 9 9
Fraction: 1011 1001 = B 9
Answer: 10011001.10111001(2) = 99.B9(16)
p. Convert B59E(16) to binary:
B = 1011, 5 = 0101, 9 = 1001, E = 1110
Answer: B59E(16) = 1011010110011110(2)
q. Convert 10011001111(2) to octal:
001 001 100 111 = 1 1 4 7
Answer: 10011001111(2) = 1147(8)
r. Convert 6017(8) to binary:
6 = 110, 0 = 000, 1 = 001, 7 = 111
Answer: 6017(8) = 110000001111(2)
💻 Updated Solutions Notice: This page features complete, step-by-step SEBA Class 9 Computer Science Chapter 1 (Introduction to Computer System) Textual Solutions updated for the 2026–27 academic session. All textbook exercises, short/long answers, block diagrams of computer units, and memory storage classifications strictly follow the latest revised Assam Board curriculum.
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