Chapter-1 : Introduction to Computers
1. Computer is derived from Latin words "Computare".
2. Computare means to calculate.
3. Computer is an electronic device which accepts raw data and process it to give meaningful result is called computer.
4. Computer works on "IPOS" cycle. Input -→ Process -→ Output -→ Storage
5. A computer system has four main parts:
* Input devices: Keyboard, mouse, scanner
* Processing unit (CPU): The brain of the computer
* Memory: Stores data (RAM, hard disk)
* Output devices: Monitor, printer, speakers
6. Hardware: Physical parts of a computer (keyboard, monitor, CPU)
7. Software: Programs that run on a computer
i) System software (e.g., operating systems like Windows)
ii) Application software (e.g., Microsoft Word)
8. Features of Computer
i) Speed – Works very fast
ii) Accuracy – Gives correct results
iii) Storage – Stores large amount of data
iv) Automation – Works automatically after instructions
v) Versatility – Can do many types of work
vi) Diligence – Does not get tired
9. Uses of Computer
i) Education – Online learning and research
ii) Office Work – Typing and record keeping
iii) Banking – Money transactions
iv) Hospital – Patient records and reports
v) Communication – Email and internet
vi) Entertainment – Games, music, movies
10. GIGO (Garbage In Garbage Out): If wrong data is entered into a computer, it gives wrong results, and if correct data is entered, it gives correct results.
11. Units of Storage in Computer
1. How many bits are there in 1 MB?
Ans: 1 MB = 1024 KB
1 KB = 1024 Bytes
1 Byte = 8 bits
So,
1 MB = 1024×1024×8
=8388608 bits
∴ 1 MB = 8388608 bits
2. How many Bits are there in 10 Bytes?
Ans:
1 Byte= 8 Bits
10 Bytes = 10 x 8 = 80 Bits
∴ 10 Bytes = 80 Bits.
3. How many bits are there in 5 bytes?
Calculation: 5 × 8 = 40
Answer: There are 40 bits in 5 bytes.
4. A single character takes up 2 bytes of memory. How many bits is that?
Calculation: 2 × 8 = 16
Answer: That is 16 bits.
5. Convert 12 bytes into bits.
Calculation: 12 × 8 = 96
Answer: 12 bytes is equal to 96 bits.
6. If a small text file contains 20 bytes of data, how many bits does it hold?
Calculation: 20 × 8 = 160
Answer: It holds 160 bits.
7. How many bytes are there in 32 bits?
Calculation: 32 ÷ 8 = 4
Answer: There are 4 bytes in 32 bits.
8. A network sends a tiny packet of 64 bits. Convert this size into bytes.
Calculation: 64 ÷ 8 = 8
Answer: The size is 8 bytes.
9. If a variable in a program uses 16 bits of storage, how many bytes does it occupy?
Calculation: 16 ÷ 8 = 2
Answer: It occupies 2 bytes.
10. Convert 800 bits into bytes.
Calculation: 800 ÷ 8 = 100
Answer: 800 bits is equal to 100 bytes.
Chapter 1: Introduction to Computers (MCQ)
Q1. The word "Computer" is derived from which language?
A) Greek B) French C) Latin D) German
Q2. What does the Latin word "Computare" mean?
A) To communicate B) To calculate C) To store D) To write
Q3. Which cycle correctly describes how a computer works?
A) Storage -> Process -> Input -> Output
B) Input -> Output -> Process -> Storage
C) Input -> Process -> Output -> Storage
D) Process -> Input -> Storage -> Output
Q4. Which of the following is considered the "brain" of the computer?
A) Monitor B) Keyboard C) CPU D) RAM
Q5. What does the acronym GIGO stand for in computer science?
A) General Input General Output
B) Garbage In Garbage Out
C) Gigabytes In Gigabytes Out
D) Global Input Output Guide
Q6. The principle of GIGO implies that if wrong data is entered into a computer:
A) The computer will fix it automatically
B) It will give a correct result anyway
C) It will give a wrong result
D) The system will crash immediately
Q7. Which of the following is an example of System Software?
A) Microsoft Word
B) Windows Operating System
C) Google Chrome
D) VLC Media Player
Q8. Physical, touchable parts of a computer system like the keyboard and monitor are called:
A) Software B) Hardware C) Malware D) Firmware
Q9. Which feature of a computer describes its ability to work continuously without getting tired?
A) Accuracy B) Versatility C) Automation D) Diligence
Q10. A computer can perform many different types of work, such as typing a document, playing a game, or calculating banking transactions. This feature is known as:
A) Speed B) Versatility C) Storage D) Automation
Q11. What is the smallest unit of data inside a computer system?
A) Nibble B) Byte C) Bit D) Kilobyte
Q12. A "Nibble" consists of how many bits?
A) 2 bits B) 4 bits C) 8 bits D) 16 bits
Q13. How many Kilobytes (KB) make up exactly 1 Megabyte (MB)?
A) 1000 KB B) 1024 KB C) 8 KB D) 1064 KB
Q14. Which of the following correctly orders units from smallest to largest size?
A) Bit -> Byte -> MB -> KB
B) Byte -> Bit -> KB -> MB
C) Bit -> Byte -> KB -> MB
D) KB -> MB -> Byte -> Bit
Q15. 1 Gigabyte (GB) is equal to:
A) 1024 Bytes B) 1024 KB C) 1024 MB D) 1024 TB
Q16. How many bits are contained in 5 bytes of data?
A) 20 bits B) 40 bits C) 50 bits D) 80 bits
Q17. If a variable inside a program uses 16 bits of storage, how many bytes does it occupy?
A) 1 byte B) 2 bytes C) 4 bytes D) 8 bytes
Q18. A small text file holds 20 bytes of data. How many bits is this equal to?
A) 160 bits B) 100 bits C) 120 bits D) 200 bits
Q19. How many bytes are there in 32 bits?
A) 2 bytes B) 4 bytes C) 8 bytes D) 16 bytes
Q20. Convert 800 bits into bytes:
A) 80 bytes B) 100 bytes C) 200 bytes D) 400 bytes
| Unit | Value |
|---|---|
| Bit | Smallest unit of data |
| 1 Bit | 0 or 1 |
| 4 Bits | 1 Nibble |
| 1 Byte | 8 bits |
| 1024 Bytes | 1 Kilobyte (KB) |
| 1024 KB | 1 Megabyte (MB) |
| 1024 MB | 1 Gigabyte (GB) |
| 1024 GB | 1 Terabyte (TB) |
| 1024 TB | 1 Petabyte(PB) |
| 1024 PB | 1 Exabyte (EB) |
| 1024 EB | 1 Zettabyte (ZB) |
Chapter 2 : Number System
Q1. What is a number system?
Ans: A number system is a method of representing numbers using different symbols or digits. It helps us write and perform calculations with numbers in mathematics and computers.
Q2. Define the base or radix of the number system.
Ans: The base or radix of a number system is the total number of unique digits or symbols used in that number system.
For example:
Decimal system has base 10 because it uses 10 digits (0–9).
Binary system has base 2 because it uses 2 digits (0 and 1).
Q3. List out the different types of number systems.
Ans: The main types of number systems are:
i) Binary Number System (Base 2)
ii) Octal Number System (Base 8)
iii) Decimal Number System (Base 10)
iv) Hexadecimal Number System (Base 16)
Q4. What is a hexadecimal number system? Write down the symbols used in the hexadecimal number system.
Ans: The hexadecimal number system is a number system with base 16. It is commonly used in computers and digital electronics. It uses the following symbols: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F
Here: A = 10 , B = 11 ,C = 12 , D = 13 , E = 14 ,F = 15
Q5) Convert the following binary to decimal number.
Example 1: Binary to Decimal
Converting the 4-bit binary number 1101₂ to base-10
1101
| Binary Digit | Power of 2 | Calculation | Value |
|---|---|---|---|
| 1 | 23 | 1 × 8 | 8 |
| 1 | 22 | 1 × 4 | 4 |
| 0 | 21 | 0 × 2 | 0 |
| 1 | 20 | 1 × 1 | 1 |
Total: 8 + 4 + 0 + 1 = 13
Example 2: Binary to Decimal
Converting the 5-bit binary number 10111₂ to base-10
10111
| Binary Digit | Power of 2 | Calculation | Value |
|---|---|---|---|
| 1 | 24 | 1 × 16 | 16 |
| 0 | 23 | 0 × 8 | 0 |
| 1 | 22 | 1 × 4 | 4 |
| 1 | 21 | 1 × 2 | 2 |
| 1 | 20 | 1 × 1 | 1 |
Total: 16 + 0 + 4 + 2 + 1 = 23
Example 3: Binary to Decimal
Converting the 6-bit binary number 111111₂ to base-10
111111
| Binary Digit | Power of 2 | Calculation | Value |
|---|---|---|---|
| 1 | 25 | 1 × 32 | 32 |
| 1 | 24 | 1 × 16 | 16 |
| 1 | 23 | 1 × 8 | 8 |
| 1 | 22 | 1 × 4 | 4 |
| 1 | 21 | 1 × 2 | 2 |
| 1 | 20 | 1 × 1 | 1 |
Total: 32 + 16 + 8 + 4 + 2 + 1 = 63
Example 4: Binary to Decimal
Converting the 8-bit binary number 10000001₂ to base-10
10000001
| Binary Digit | Power of 2 | Calculation | Value |
|---|---|---|---|
| 1 | 27 | 1 × 128 | 128 |
| 0 | 26 | 0 × 64 | 0 |
| 0 | 25 | 0 × 32 | 0 |
| 0 | 24 | 0 × 16 | 0 |
| 0 | 23 | 0 × 8 | 0 |
| 0 | 22 | 0 × 4 | 0 |
| 0 | 21 | 0 × 2 | 0 |
| 1 | 20 | 1 × 1 | 1 |
Total: 128 + 0 + 0 + 0 + 0 + 0 + 0 + 1 = 129
Example 5: Binary to Decimal
Converting the 8-bit binary number 11001010₂ to base-10
11001010
| Binary Digit | Power of 2 | Calculation | Value |
|---|---|---|---|
| 1 | 27 | 1 × 128 | 128 |
| 1 | 26 | 1 × 64 | 64 |
| 0 | 25 | 0 × 32 | 0 |
| 0 | 24 | 0 × 16 | 0 |
| 1 | 23 | 1 × 8 | 8 |
| 0 | 22 | 0 × 4 | 0 |
| 1 | 21 | 1 × 2 | 2 |
| 0 | 20 | 0 × 1 | 0 |
Total: 128 + 64 + 0 + 0 + 8 + 0 + 2 + 0 = 202
A. Calculate:
1. (0011)2 = (?)10 2. (0101)2 = (?)10
3. (1010)2 = (?)10 4. (1111)2 = (?)10
5. (001101)2 = (?)10 6. (110010)2 = (?)10
7. (10000001)2 = (?)10 8. (10101010)2 = (?)10
9. (11010111)2 = (?)10 10. (11111100)2 = (?)10
11. (1001101101)2 = (?)10 12. (1111111111)2 = (?)10
