Get complete, authentic, and step-by-step solutions for DAV Class 4 Hands-On: A Book of ICT Chapter 1: Computer—A Machine. All questions, research activities, hardware vs. software identification, memory classification, storage calculation tables, and assessment activities are fully solved strictly based on the prescribed DAV CMC textbook curriculum.
Chapter Overview & Learning Objectives
Core Topics Covered in Chapter 1:
- Concept of Information Processing (Input → Process → Output cycle).
- Primary Memory (RAM & ROM) vs. Secondary Memory (Hard Disk, CD, DVD, Pen Drive).
- Units of Computer Memory: Bit, Byte, Kilobyte (KB), Megabyte (MB), Gigabyte (GB).
- Hardware (physical touchable parts) vs. Software (programs and instructions).
- Inside the System Unit (CPU, Motherboard, RAM, Hard Disk, SMPS).
- Safe disposal of electronic waste (E-Waste Management).
Activity 1: Machines Around Us (Textbook Page 1)
Question: List the names of various machines that you find around you at home or in school, under the correct column, and also write what the machine needs to perform the desired work (task).
| Machine Name | Needs to Perform Desired Work (Energy / Input) | Main Function / Purpose |
|---|---|---|
| Washing Machine | Electricity and Water | Washes and rinses dirty clothes automatically. |
| Refrigerator | Electricity | Preserves food, vegetables, and cools water. |
| Bicycle | Human Power (Muscular energy) | Helps in traveling short distances without fuel. |
| Car / Bus | Fuel (Petrol / Diesel) or Electricity | Transportation of people and goods. |
| Calculator | Battery / Solar energy | Performs fast mathematical calculations. |
| Computer | Electricity and User Instructions | Processes raw data into meaningful information. |
“All machines work on instructions given to them.”
Research Activity: Computer Memory Classification (Textbook Page 14)
1. Which memory will be used for the following? Write ‘P’ for Primary memory and ‘S’ for Secondary Memory:
| S.No. | Activity / Operation | Memory Type (P / S) |
|---|---|---|
| 1. | Playing a game on a website | P (Primary Memory / RAM) |
| 2. | Tux Paint is stored in | S (Secondary Memory / Hard Disk) |
| 3. | When we type in Wordpad we use | P (Primary Memory / RAM) |
| 4. | Saving a drawing | S (Secondary Memory / Hard Disk) |
Explanation: Primary memory (RAM) is temporary memory used while programs are actively running or data is being typed. Secondary memory (Hard Disk) is permanent memory used to store applications and saved files so they remain safe even when the computer is turned off.
Memory Units & Storage Capacity (Textbook Page 14-15)
Understanding Memory Units:
- Bit (Binary Digit): The smallest unit of data, represented by 0 or 1.
- 1 Byte: A group of 8 bits (denoted by B).
- 1 Kilobyte (KB): 1024 Bytes
- 1 Megabyte (MB): 1024 Kilobytes (KB)
- 1 Gigabyte (GB): 1024 Megabytes (MB)
- 1 Terabyte (TB): 1024 Gigabytes (GB)
Storage Capacity of Computer (Sample Lab Activity):
| Disk Storage Parameter | Observed Capacity in Lab |
|---|---|
| Total Hard Disk Space | 512 GB (or 1 TB) |
| Used Space | 180 GB |
| Unused / Free Space | 332 GB |
Differences: Storage Devices (Textbook Page 15)
2. Explore how CD is different from a DVD? Write your findings in the space provided:
| Feature | Compact Disc (CD) | Digital Versatile Disc (DVD) |
|---|---|---|
| Storage Capacity | Can store up to 700 MB of data. | Can store 4.7 GB up to 17 GB (over 6 times more than a CD). |
| Laser Wavelength | Uses infrared laser with longer wavelength (780 nm). | Uses red laser with narrower wavelength (650 nm), allowing tighter data tracks. |
| Primary Usage | Mainly used for audio songs, small documents, and lightweight software. | Used for high-definition movies, multi-media presentations, and heavy video games. |
3. Explore and write any three differences between Pen drive & Hard disk:
| Feature | Pen Drive (Flash Drive) | Hard Disk (HDD) |
|---|---|---|
| Portability | Small, lightweight, and easily carried in a pocket. | Heavier and larger; usually fixed inside the CPU cabinet. |
| Storage Capacity | Moderate capacity (typically 8 GB, 16 GB, 32 GB, 64 GB, 128 GB). | Very large storage capacity (typically 500 GB, 1 TB, 2 TB, or more). |
| Mechanism | Uses solid-state flash memory chips with no moving parts. | Contains rotating magnetic platters with moving read/write heads. |
4. Collect information about the different storage capacity of Pendrive:
| Pendrive Type | Storage Capacity | Typical Content Stored |
|---|---|---|
| Standard Pen Drive | 16 GB / 32 GB | School projects, presentations, and photos. |
| High-Capacity Pen Drive | 64 GB / 128 GB | Multiple HD movies, software setups, and backup files. |
| Ultra-Capacity Pen Drive | 256 GB / 512 GB | Complete system backups and 4K video files. |
Hands On: Hardware vs. Software (Textbook Page 15-16)
1. In the computer lab observe and list the parts of computer which you can touch. Write the use of each such part:
| Part (Hardware) | Use of the Part |
|---|---|
| Monitor | Output device that displays visual output, text, and pictures. |
| Keyboard | Input device containing keys to type words, numbers, and commands. |
| Mouse | Pointing device used to select, click, drag, and draw on the screen. |
| System Unit (CPU Cabinet) | Houses internal electronic components that process calculations and control the system. |
| Printer | Produces hard copy (paper printout) of pictures and documents. |
| Speakers / Headphones | Audio output device to hear sounds, voice, and music. |
2. Observe and make a list of software installed in your computer lab and their purpose:
| Software | Purpose of Software |
|---|---|
| Tux Paint | Creative drawing and coloring application for primary students. |
| LibreOffice Writer / MS Word | Word processing software for typing letters, essays, and stories. |
| MSW Logo | Educational programming environment to draw shapes using turtle commands. |
| Google Chrome / Web Browser | Browsing the internet and searching educational information. |
| Windows / Linux Operating System | System software that manages computer hardware and coordinates all applications. |
Can you touch the software(s)?
Answer: No, software consists of programs and digital instructions stored electronically. We can see software working on the monitor screen, but we cannot physically touch it.
Inside the System Unit (Textbook Page 16)
List of hardware components inside the System Unit:
- Motherboard: The main circuit board that connects CPU, memory, and all peripheral devices.
- Microprocessor (CPU): The central brain of the computer that performs all calculations and logical decisions.
- RAM (Random Access Memory): High-speed temporary memory modules where active programs run.
- Hard Disk Drive (HDD / SSD): Permanent secondary storage unit storing the operating system and files.
- SMPS (Switched-Mode Power Supply): Converts AC wall electricity into regulated DC power for internal components.
- Cooling Fan & Heat Sink: Dissipates heat generated by the fast-working processor.
Research Activity: E-Waste Management (Textbook Page 17)
Question: Find out what happens to the computer or cellphone which is thrown/discarded by people?
Answer:
When discarded computers, mobile phones, and electronic gadgets are thrown into ordinary dustbins, they become Electronic Waste (E-Waste).
1. Environmental Hazard: Electronics contain toxic elements such as lead, mercury, cadmium, and arsenic. If dumped in open landfills, these poisonous chemicals seep into the soil and pollute underground drinking water.
2. Recycling Solution: Discarded gadgets should always be handed over to authorized e-waste collection centers. Specialized recyclers safely dismantle the machines, recover valuable metals (like copper, aluminum, silver, and gold), and dispose of dangerous materials safely without polluting mother earth.
Assessment Activity (Textbook Page 17)
1. Name the storage device to store:
- 5 movies or game software → Hard Disk / DVD / High-Capacity Pen Drive
- Few songs and listening them in the car → Pen Drive (USB Flash Drive)
- To transfer your drawing from one computer to another → Pen Drive (Flash Drive)
Write the number of:
- (a) Alphabet keys on the keyboard: 26 keys (A to Z)
- (b) Function keys on the keyboard: 12 keys (F1 to F12)
- (c) Number keys on the keyboard: 10 keys (0 to 9, placed in two sets: top number row and numeric keypad)
- (d) Combination keys: 3 keys (Shift, Ctrl, Alt)
Identify the Keys:
- 2. Key used to give space: Spacebar (the longest key on the keyboard)
- 3. Key with @ sign: Number 2 key (typed using Shift + 2)
- 4. Key used with alphabet keys to write uppercase letters and number keys to type special characters: Shift Key
- 5. Toggle key: Caps Lock Key (also Num Lock and Scroll Lock)
- 6. Keys to restart your computer: Ctrl + Alt + Delete
- What is the output that we get from printer called? Hard Copy (Printout)
Frequently Asked Questions (FAQ)
Q1: Why is RAM called volatile memory?
Ans: RAM is called volatile because it holds data only as long as the computer is powered ON. The moment the computer is switched off or restarted, all data in RAM is wiped out.
Q2: What is the difference between Soft Copy and Hard Copy?
Ans: Soft Copy is the digital output displayed on the monitor screen, whereas Hard Copy is the physical printout produced on paper by a printer.