Unit 1: Fundamentals of Computer - Subjective Questions

A computer is an electronic device that accepts data as input, processes it according to a set of instructions (program), and produces meaningful information as output while having the ability to store data.

Main characteristics of a computer:

• Speed: A computer can perform millions of calculations per second. Operations are measured in milliseconds (), microseconds (), nanoseconds (), and picoseconds ().
• Accuracy: Computers produce error-free results. Errors usually arise due to wrong input by humans (GIGO - Garbage In, Garbage Out).
• Diligence: A computer can work continuously for hours without getting tired or bored, unlike humans.
• Versatility: It can perform different types of tasks such as calculations, playing music, and browsing at the same time.
• Storage: It can store huge amounts of data and retrieve it whenever required.
• Automation: Once a program is loaded, the computer works automatically without human intervention.
• Reliability: Consistent and dependable performance over long periods.

Example: A banking system uses a computer to process thousands of transactions accurately and quickly.

Computers have evolved through five generations, each marked by a major technological development.

First Generation (1940-1956): Vacuum Tubes

• Used vacuum tubes for circuitry and magnetic drums for memory.
• Very large, consumed huge power, generated heat.
• Used machine language. Example: ENIAC, UNIVAC.

Second Generation (1956-1963): Transistors

• Transistors replaced vacuum tubes, making computers smaller, faster, cheaper.
• Used assembly language and languages like FORTRAN, COBOL.
• Example: IBM 1401.

Third Generation (1964-1971): Integrated Circuits (ICs)

• Transistors miniaturized on silicon chips (ICs).
• Increased speed and efficiency, used keyboards and monitors.
• Example: IBM 360.

Fourth Generation (1971-Present): Microprocessors

• Thousands of ICs on a single chip (microprocessor).
• Led to personal computers (PCs).
• Example: Intel 4004, IBM PC.

Fifth Generation (Present and Beyond): Artificial Intelligence

• Based on AI, parallel processing, and VLSI/ULSI technology.
• Uses natural language processing.
• Example: Modern AI-based systems and quantum computers.

The block diagram of a computer shows the basic functional units and how data flows between them.

     +----------------+

     +-------v--------+
     | Memory Unit    |
     +----------------+

Components:

• Input Unit: Accepts data and instructions from the user (e.g., keyboard, mouse) and converts them into machine-readable form.
• Central Processing Unit (CPU): The brain of the computer, consisting of:
  • Arithmetic Logic Unit (ALU): Performs arithmetic (add, subtract) and logical (compare) operations.
  • Control Unit (CU): Directs and coordinates all operations; fetches, decodes, and executes instructions.
• Memory Unit: Stores data, instructions, and results. Includes primary memory (RAM, ROM) and secondary memory (hard disk).
• Output Unit: Displays processed information to the user (e.g., monitor, printer).

Data flow: Input Unit → CPU (processing with Memory) → Output Unit.

Computers are used in almost every field of life. Some important applications are:

• Education: E-learning, online classes, digital libraries, computer-based training, and research.
• Banking: ATMs, online banking, electronic fund transfers (EFT), and account management.
• Healthcare/Medicine: Patient records, diagnostic tools (MRI, CT scan), telemedicine, and hospital management.
• Business: Inventory management, payroll, accounting, and e-commerce.
• Government: e-Governance, income tax filing, biometric identity systems (Aadhaar), and record keeping.
• Entertainment: Gaming, video/audio editing, animation, and streaming.
• Industry: Automation, robotics, CAD/CAM, and process control.
• Communication: Email, video conferencing, social media, and messaging.
• Science & Research: Simulations, weather forecasting, and space research.
• Transportation: Railway/airline reservation, GPS navigation, and traffic control.

A number system is a method of representing numbers using a set of symbols and rules. Each number system has a base (radix) which indicates the total number of digits it uses.

Types of number systems:

• Decimal Number System (Base 10): Uses digits to . It is the number system used by humans in daily life. Example: .
• Binary Number System (Base 2): Uses only two digits, and . It is the fundamental language of computers. Example: .
• Octal Number System (Base 8): Uses digits to . Each octal digit represents three binary digits. Example: .
• Hexadecimal Number System (Base 16): Uses digits to and letters to (where ). Each hex digit represents four binary digits. Example: .

Computers use the binary system internally because electronic circuits have two states: ON (1) and OFF (0).

Decimal to Binary (divide by 2):

Reading remainders bottom to top:

Decimal to Octal (divide by 8):

• remainder
• remainder
• remainder

So

Decimal to Hexadecimal (divide by 16):

• remainder
• remainder

So

Binary to Decimal (multiply each bit by its positional weight ):

Binary to Octal (group in 3 bits from right):

• , ,

So

Binary to Hexadecimal (group in 4 bits from right):

• ,

So

Primary Memory vs Secondary Memory:

Summary: Primary memory holds data currently in use and is fast but temporary, while secondary memory stores data permanently but is slower.

The CPU (Central Processing Unit) has two primary functional components: the Control Unit and the Arithmetic Logic Unit.

Control Unit (CU):

• Acts as the central nervous system of the computer.
• Fetches instructions from memory, decodes them, and executes them.
• Controls and coordinates the operations of all units (input, output, memory, ALU).
• Generates control signals to direct data flow.
• It does not perform actual processing of data.

Arithmetic Logic Unit (ALU):

• Performs all arithmetic operations: addition, subtraction, multiplication, and division.
• Performs all logical operations: comparison (greater than, less than, equal to) and logical decisions (AND, OR, NOT).
• Uses registers to hold data temporarily during processing.

Together with registers, the CU and ALU form the CPU, which is called the brain of the computer.

(a) Octal to Decimal :

Multiply each digit by powers of 8:

(b) Hexadecimal to Decimal :

Here and . Multiply each digit by powers of 16:

Comparison between First and Fourth Generation Computers:

Conclusion: Fourth generation computers are far smaller, faster, cheaper, and more reliable than first generation computers due to microprocessor technology.

Data representation refers to the methods used to store and process data inside a computer. Since computers understand only two states (0 and 1), all data (numbers, text, images, audio) is represented in binary form.

Basic units of data:

• Bit (Binary Digit): The smallest unit of data, either or .
• Nibble: A group of 4 bits.
• Byte: A group of 8 bits; the basic unit for storing one character.

Units of memory measurement:

Character encoding schemes like ASCII, EBCDIC, and Unicode are used to represent characters using binary codes.

Computers in Education:

• E-learning and online classes: Enable remote learning through video lectures and virtual classrooms.
• Digital libraries: Provide access to e-books, journals, and research papers.
• Computer-Aided Instruction (CAI): Interactive tutorials and simulations improve understanding.
• Examinations: Online tests, automated grading, and result processing.
• Research: Data analysis, simulations, and access to global information.

Computers in Healthcare:

• Patient records management: Electronic Health Records (EHR) store patient history digitally.
• Diagnostic tools: Devices like MRI, CT scans, and ultrasound use computers for imaging.
• Telemedicine: Enables remote consultation between doctors and patients.
• Hospital management: Manages appointments, billing, inventory, and staff.
• Surgery: Robotic and computer-assisted surgery increases precision.
• Drug research: Simulations and analysis speed up medicine development.

In both sectors, computers improve efficiency, accuracy, and accessibility of services.

Binary addition rules: , , , (write 0, carry 1), (write 1, carry 1).

(a) :

1 0 1 1

• 1 1 0 1

  1 1 0 0 0

Step by step (right to left):

• → write 0, carry 1
• → write 0, carry 1
• → write 0, carry 1
• → write 1, carry 1
• carry

Result:

(b) :

1 1 0 0 1

• 1 0 1 1 0

  1 0 1 1 1 1

Result:

Verification: ✓

A microprocessor is a single integrated circuit (chip) that contains the complete Central Processing Unit (CPU) of a computer. It performs arithmetic, logic, control, and input/output operations.

Structure: It integrates the ALU, Control Unit, and registers onto a single silicon chip using VLSI (Very Large Scale Integration) technology. The first microprocessor was the Intel 4004 (1971).

Importance in modern computers:

• Miniaturization: Reduced the size of computers from room-sized machines to portable devices.
• Cost reduction: Made computers affordable for individuals, leading to the personal computer (PC) revolution.
• Increased speed: High processing speeds measured in GHz.
• Low power consumption: More energy-efficient than earlier technologies.
• Reliability: Fewer components mean fewer failures.
• Versatility: Used in PCs, laptops, smartphones, embedded systems, and appliances.

Conclusion: The microprocessor marked the beginning of the fourth generation and is the foundation of all modern computing devices.

To convert a decimal fraction to binary, we multiply the fractional part repeatedly by 2 and record the integer part of each result.

Procedure for :

The fractional part becomes , so we stop.

Reading the integer parts from top to bottom:

Therefore,

Verification: ✓

Computers can be classified based on the type of data they process:

Analog Computers:

• Process continuous data (physical quantities like temperature, pressure, voltage).
• Give approximate results.
• Used in scientific and engineering applications.
• Example: Speedometer, analog voltmeter.

Digital Computers:

• Process discrete data in the form of digits (0s and 1s).
• Give highly accurate results.
• Used for general purpose computing.
• Example: Personal computers, laptops.

Hybrid Computers:

• Combine features of both analog and digital computers.
• Analog part measures physical quantities; digital part processes them.
• Used in specialized applications.
• Example: Computers used in hospitals (ICU monitors), and in petrol pumps.

Input Devices:
Input devices are used to enter data and instructions into the computer. They convert human-readable information into machine-readable form.

• Keyboard: Used to type text, numbers, and commands.
• Mouse: A pointing device used to select and move items on screen.
• Scanner: Converts printed documents and images into digital form.
• Microphone: Captures audio input.
• Others: Joystick, light pen, webcam, barcode reader.

Output Devices:
Output devices display or present the processed information (result) to the user in a human-readable form.

• Monitor: Displays visual output (text, images, video).
• Printer: Produces hard copy (paper output) of documents.
• Speaker: Produces sound/audio output.
• Projector: Displays output on a large screen.
• Others: Plotter, headphones.

Note: Some devices like touch screens act as both input and output devices.

Computers use the binary number system (base 2) internally rather than the decimal system for the following reasons:

• Two-state electronic devices: Computer circuits are made of transistors and switches that have only two stable states — ON (1) and OFF (0). Binary maps naturally to these two states.
• Reliability: With only two states, it is easy to distinguish between them, reducing the chance of error. Representing 10 different voltage levels (for decimal) would be complex and error-prone.
• Simplicity of design: Digital circuits and logic gates (AND, OR, NOT) work on binary logic (true/false), making hardware design simpler and cheaper.
• Ease of computation: Binary arithmetic (addition, subtraction) is simple to implement using logic circuits.
• Compatibility: Binary directly relates to Boolean algebra, which is the foundation of digital electronics.
• Data storage: Storage devices store data as magnetized/unmagnetized or charged/uncharged states, corresponding to 1 and 0.

Conclusion: The binary system is the most efficient and reliable way to represent and process data in electronic computers.

Part 1: Binary to Decimal

For the integer part, use positive powers of 2; for the fraction, use negative powers.

Integer part :

Fractional part :

Therefore,

Part 2: Binary to Hexadecimal

Group into 4 bits from the right:

Therefore,