Introduction to Computers: Exercise Solutions
How to Use This Page
Read the Samacheer Kalvi textbook chapter first. Then use this page to revise: attempt the textbook questions on your own, then compare with the model answers below. Pay special attention to the Common Mistakes section and the Exam Checklist before your test.
Key Concepts (Quick Recap)
| Term | Definition |
|---|---|
| Input Unit | Devices that feed data into the computer (keyboard, mouse, scanner) |
| CPU | Central Processing Unit — the brain of the computer that processes data |
| ALU | Arithmetic and Logic Unit — performs calculations and comparisons |
| Control Unit | Directs and coordinates all computer operations |
| Memory Unit | Stores data, instructions, and results (primary and secondary) |
| Output Unit | Devices that display or produce processed results (monitor, printer) |
| IPO Cycle | Input-Process-Output cycle — the fundamental working principle |
| Vacuum Tubes | First-generation switching devices, large and heat-producing |
| Transistors | Second-generation devices, smaller and more reliable than vacuum tubes |
| Integrated Circuits (ICs) | Third-generation technology — many transistors on a single chip |
| Microprocessors | Fourth-generation VLSI technology — entire CPU on a chip |
| Artificial Intelligence | Fifth-generation focus — computers that can learn and reason |
I. Choose the Correct Answer (MCQ)
Q1. The brain of the computer is:
(a) Memory (b) CPU ✓ (c) Input Unit (d) Output Unit
Q2. The full form of IPO is:
(a) Input Process Output ✓ (b) Input Print Output (c) Input Program Output (d) Internal Process Output
Q3. First-generation computers used:
(a) Transistors (b) ICs (c) Vacuum tubes ✓ (d) Microprocessors
Q4. Which generation of computers used transistors?
(a) First Generation (b) Second Generation ✓ (c) Third Generation (d) Fourth Generation
Q5. ENIAC belongs to which generation?
(a) First Generation ✓ (b) Second Generation (c) Third Generation (d) Fourth Generation
Q6. The component that performs arithmetic and logical operations is:
(a) Control Unit (b) ALU ✓ (c) Memory (d) Input Unit
Q7. VLSI stands for:
(a) Very Large Scale Integration ✓ (b) Very Low Scale Integration (c) Very Large System Integration (d) Variable Large Scale Integration
Q8. Which of the following is an input device?
(a) Monitor (b) Printer (c) Keyboard ✓ (d) Speaker
Q9. UNIVAC is an example of:
(a) First Generation Computer ✓ (b) Second Generation Computer (c) Third Generation Computer (d) Fourth Generation Computer
Q10. Fifth-generation computers are expected to use:
(a) Vacuum tubes (b) Transistors (c) ICs (d) Artificial Intelligence ✓
II. Very Short Answer Questions (2 Marks)
Q1. What is a computer?
Q2. What is the IPO cycle?
This cycle repeats continuously during any computer operation.
Q3. What is the function of the Control Unit?
Q4. Name any two input devices.
Other input devices include scanner, microphone, joystick, and barcode reader.
Q5. What are vacuum tubes?
Q6. Define memory unit.
III. Short Answer Questions (3 Marks)
Q1. Explain the five generations of computers.
| Generation | Period | Technology Used | Example |
|---|---|---|---|
| First | 1940–1956 | Vacuum tubes | ENIAC, UNIVAC, EDVAC |
| Second | 1956–1963 | Transistors | IBM 1401, CDC 1604, Honeywell 400 |
| Third | 1964–1971 | Integrated Circuits (ICs) | IBM 360, PDP-8, PDP-11 |
| Fourth | 1971–Present | Microprocessors (VLSI) | IBM PC, Apple Macintosh |
| Fifth | Present & Beyond | Artificial Intelligence (ULSI) | Still in development |
Each generation saw a significant reduction in size and cost, along with improvements in speed, reliability, and storage capacity.
Q2. Distinguish between input and output devices.
| Feature | Input Devices | Output Devices |
|---|---|---|
| Function | Send data into the computer | Display or produce results |
| Direction | User → Computer | Computer → User |
| Examples | Keyboard, Mouse, Scanner, Microphone, Light pen | Monitor, Printer, Speaker, Projector, Plotter |
| Data Type | Raw data and commands entered by the user | Processed information and results |
| Conversion | Human-readable → Machine-readable | Machine-readable → Human-readable |
Input devices allow the user to communicate with the computer, while output devices allow the computer to communicate results to the user.
Q3. Write a short note on the classification of computers based on size.
1. Supercomputers — The largest and most powerful computers; used for complex tasks like weather forecasting, space research, and scientific simulations. Example: PARAM, Cray, Fugaku. 2. Mainframe Computers — Large systems that support hundreds of users simultaneously; used in banking, airlines, and government. Example: IBM mainframes. 3. Minicomputers — Medium-sized computers that serve multiple users; used in small businesses and laboratories. Example: PDP-11, VAX. 4. Microcomputers (Personal Computers) — Small, affordable computers for individual use at home and office. Includes desktops, laptops, tablets, and smartphones.
Q4. Explain the role of ALU in the CPU.
1. Arithmetic Operations — Addition, subtraction, multiplication, and division of numerical data. 2. Logical Operations — Comparisons such as greater than, less than, and equal to. These comparisons help the computer make decisions.
The ALU receives data from memory, processes it, and sends the result back to memory or to the output unit. It works under the direction of the Control Unit, which tells the ALU which operation to perform.
IV. Long Answer Questions (5 Marks)
Q1. Explain the basic structure of a computer with a neat block diagram.
1. Input Unit: Accepts data from the user through devices like keyboard and mouse. It converts human-readable data into machine-readable form and sends it to the CPU for processing. Without the input unit, the computer cannot receive any data or instructions.
2. Central Processing Unit (CPU): The brain of the computer. It has two sub-units:
- Arithmetic and Logic Unit (ALU): Performs all arithmetic calculations (add, subtract, multiply, divide) and logical comparisons (greater than, less than, equal to).
- Control Unit (CU): Coordinates and directs all operations. It fetches instructions from memory, decodes them, and sends control signals to other units to execute instructions.
3. Memory Unit: Stores data, instructions, and results.
- Primary Memory (RAM/ROM): Fast, temporary storage directly accessible by CPU. RAM is volatile; ROM is non-volatile.
- Secondary Memory (Hard disk, SSD): Permanent, larger storage for files and programs.
4. Output Unit: Displays processed results through devices like monitors and printers. It converts machine-readable data into human-readable form.
The flow of data: Input → CPU (ALU + CU) with Memory ↔ Output
Q2. Compare the five generations of computers in detail.
| Feature | 1st Gen | 2nd Gen | 3rd Gen | 4th Gen | 5th Gen |
|---|---|---|---|---|---|
| Period | 1940–56 | 1956–63 | 1964–71 | 1971–Present | Present & Beyond |
| Technology | Vacuum tubes | Transistors | ICs | VLSI/Microprocessors | AI/ULSI |
| Size | Room-sized | Smaller | Smaller | Portable/Handheld | Very small |
| Speed | Very slow (ms) | Slow (μs) | Faster (ns) | Very fast (ps) | Extremely fast |
| Cost | Very high | High | Lower | Affordable | Decreasing |
| Reliability | Unreliable | More reliable | Reliable | Very reliable | Highly reliable |
| Power Consumption | Very high | Lower | Lower | Low | Very low |
| Memory | Magnetic drum | Magnetic core | Magnetic core & semiconductor | Semiconductor | Advanced semiconductor |
| Examples | ENIAC, UNIVAC, EDVAC | IBM 1401, CDC 1604 | IBM 360, PDP-8 | IBM PC, Apple Macintosh | AI machines |
| Language | Machine | Assembly | High-level | High-level (C, C++) | Natural language |
Key advancements: Each generation reduced size, cost, and power consumption while increasing speed, reliability, and ease of use. The shift from vacuum tubes to transistors to ICs to microprocessors represents a continuous miniaturisation of components.
Q3. Describe the different types of computers based on purpose and working.
Based on Purpose:
1. General Purpose Computers — Designed to handle a wide variety of tasks. Most personal computers fall in this category. They can run different software for different applications — word processing, gaming, browsing, programming, etc. They are versatile but not optimised for any single task.
2. Special Purpose Computers — Designed for a specific task only. Examples include computers in washing machines, ATMs, medical equipment, and traffic control systems. They are efficient for their dedicated function but cannot perform other tasks.
Based on Working Mechanism:
1. Analog Computers — Work with continuous data (physical quantities like temperature, voltage, pressure). Used in scientific instruments, speedometers, and thermometers. They provide approximate results and are fast for real-time processing.
2. Digital Computers — Work with discrete data (0s and 1s — binary). Most modern computers are digital. They are accurate, versatile, and can store large amounts of data. Examples: laptops, desktops, smartphones.
3. Hybrid Computers — Combine features of both analog and digital computers. Used in hospitals (ICU monitoring), petrol pumps, and scientific research where both continuous and discrete data need processing. They offer the speed of analog computers and the accuracy of digital computers.
Q4. Explain the functions of each unit of a computer in detail.
Common Mistakes to Avoid
- Confusing the ALU (calculations) with the Control Unit (coordination) — the ALU computes; the CU directs.
- Stating that ENIAC is a second-generation computer — it used vacuum tubes and is first-generation.
- Writing IPO as "Input Print Output" instead of "Input Process Output."
- Forgetting that RAM is volatile (loses data when power is off) while ROM is non-volatile.
- Listing only one example per generation — try to remember at least two.
- Saying that transistors were used in first-generation computers — they replaced vacuum tubes in the second generation.
- Confusing microcomputers with microprocessors — a microcomputer is the whole system; a microprocessor is just the CPU chip.
- Writing that hybrid computers are only digital — they combine analog and digital features.
- Mixing up input and output device directions — input goes from user to computer; output goes from computer to user.
- Omitting the memory unit when drawing the block diagram of a computer — memory is a core component.
Exam Checklist
- [ ] Can you draw and label the block diagram of a computer?
- [ ] Can you list the technology and at least two examples for each of the five generations?
- [ ] Can you explain the role of the ALU and the Control Unit separately?
- [ ] Can you classify computers by size (super, mainframe, mini, micro)?
- [ ] Can you classify computers by purpose (general vs. special) and working (analog, digital, hybrid)?
- [ ] Do you know the full forms of ENIAC, UNIVAC, VLSI, ULSI, and IPO?
- [ ] Can you distinguish between primary and secondary memory?
- [ ] Can you name at least three input and three output devices with their functions?
- [ ] Can you explain the IPO cycle with examples?
- [ ] Can you compare all five generations in terms of technology, speed, cost, and examples?