3.1   Explain the difference between (any 2 of a, b, c)

3.2   Enlist the Components and Slots Normally Assembled on a Motherboard

The motherboard (also called the system board or main board) is the primary circuit board that connects all components of the computer. The following components and expansion slots are found on a typical motherboard:

• CPU Socket – Holds the Central Processing Unit (e.g., Intel LGA or AMD AM socket).
• RAM Slots (DIMM) – Slots to install RAM modules (e.g., DDR4 DIMM slots).
• BIOS/CMOS Chip – Stores firmware to start (boot) the computer.
• CMOS Battery – A small cell battery to retain BIOS settings and system clock.
• Chipset – North Bridge (connects CPU to RAM, AGP) and South Bridge (connects to PCI, USB, IDE, etc.).
• PCI Slots – Peripheral Component Interconnect slots for expansion cards (Sound, NIC).
• AGP Slot – Accelerated Graphics Port for graphics/video cards.
• ISA Slots – Industry Standard Architecture (older expansion slots).
• IDE / SATA Connectors – To connect Hard Disk and CD/DVD drives.
• Floppy Connector – For connecting floppy disk drives.
• Power Connectors – ATX 20/24-pin connector for power supply.
• USB Headers – For front-panel USB ports.
• PS/2 Connectors – For keyboard and mouse.
• Serial & Parallel Ports – COM ports and LPT port for older peripherals.
• Heat Sink Mounting Holes – For securing CPU cooler.

3.3   List any Four Input and Output Devices and Explain any One

Input Devices: Keyboard, Mouse, Scanner, Joystick, Light Pen, Microphone

Output Devices: Monitor (VDU), Printer, Speaker, Plotter, Projector

A Monitor is the primary output device of a computer. It displays text, images, video, and graphical data in real time.

• Types: CRT (Cathode Ray Tube), LCD (Liquid Crystal Display), LED, OLED.
• Resolution: Determined by number of pixels (e.g., 1920×1080 Full HD).
• Colour depth: Number of colours it can display (e.g., 16-bit, 24-bit True Colour).
• Refresh Rate: Number of times screen is redrawn per second (measured in Hz).
• LCD/LED monitors are thin, consume less power, and produce less radiation than CRT monitors.

3.4   Write Advantages and Disadvantages of Laser Printer

• Very high print speed (up to 200 pages per minute for commercial models).
• Produces very high quality, sharp, and precise text and graphics output.
• Low cost per page when used extensively (economical for large volumes).
• Quiet operation compared to impact printers.
• No smudging — toner is fused to paper using heat, giving a dry, smudge-free finish.
• Handles a large variety of paper types and sizes.

• High initial purchase cost compared to ink-jet printers.
• Toner cartridges are expensive to replace.
• Bulkier and heavier than ink-jet printers.
• Ozone gas may be emitted during printing — requires ventilation.
• Colour laser printers are significantly more expensive than colour ink-jets.
• Not suitable for printing on special media like fabric or glossy photo paper.

3.5   What is Multimedia and Sound Card? Write their Applications

Multimedia refers to the integration of multiple forms of content — text, audio, images, animation, video, and interactivity — delivered through a computer or electronic device. The word "multi" means many and "media" means medium of communication.

Applications of Multimedia:

• Education – e-learning, interactive CD-ROMs, virtual classrooms.
• Entertainment – video games, digital movies, music players.
• Business – presentations, video conferencing, digital advertising.
• Medicine – medical imaging, simulation for surgery training.
• Communication – video calls, social media, multimedia messaging.

Sound Card (Audio Card): A sound card is an expansion card (or integrated chip on the motherboard) that enables the computer to produce and record sound. It converts digital audio data to analog signals (for speakers) and analog signals to digital (for microphone input).

Applications of Sound Card:

• Playing audio (music, video soundtracks) through speakers or headphones.
• Voice recognition and voice input via microphone.
• Audio/music production and recording software.
• Gaming — real-time sound effects and surround sound.
• Video conferencing and Internet telephony (VoIP).

3.6   Explain the Concept of Interrupt

An Interrupt is a signal sent to the CPU that temporarily halts (interrupts) the currently running program, causing the CPU to execute a special routine called an Interrupt Service Routine (ISR) or Interrupt Handler. After the ISR completes, the CPU resumes the original program.

• Hardware Interrupt: Generated by external devices (e.g., keyboard press, mouse click, disk I/O completion). Also called Maskable (can be disabled) or Non-Maskable (NMI, cannot be disabled — used for critical errors).
• Software Interrupt: Generated by a program (e.g., INT 21H in DOS) to request an OS service.
• Internal Interrupt (Trap/Exception): Caused by errors within the CPU — e.g., division by zero, invalid opcode, overflow.

Importance: Interrupts allow efficient multitasking, real-time response to hardware events, and are fundamental to how operating systems manage I/O operations without wasting CPU cycles in polling loops.

4.1   Write the Difference between Physical and Logical Memory

4.2   State Different Types of Semiconductor Memories and Explain Any One

Semiconductor memories are electronic memories built from semiconductor materials (silicon). They are classified as:

• RAM (Random Access Memory) — Volatile
  • SRAM (Static RAM)
  • DRAM (Dynamic RAM)
• ROM (Read Only Memory) — Non-Volatile
  • PROM (Programmable ROM)
  • EPROM (Erasable Programmable ROM)
  • EEPROM (Electrically Erasable Programmable ROM)
• Flash Memory — Non-Volatile (used in pen drives, SSDs)
• Cache Memory — High-speed volatile memory between CPU and RAM

EPROM is a type of ROM that can be programmed by the user using a special device called a PROM programmer/burner. Unlike PROM, it can be erased by exposing it to ultraviolet (UV) light for 15–20 minutes through a quartz window on the chip, and then reprogrammed.

• Non-volatile — retains data even when power is off.
• Used for BIOS chips and embedded system firmware.
• Can be erased and reused multiple times.
• Identified by a small transparent quartz window on the chip.

4.3   What is Meant by Impact and Non-Impact Printer? Explain Any One Impact Printer

Impact Printer: A printer that forms characters by physically striking an inked ribbon or the paper surface. It makes noise during printing. Examples: Dot Matrix Printer, Daisy Wheel Printer, Line Printer.

Non-Impact Printer: A printer that forms characters without any physical contact between the print head and paper. It is quiet and produces high-quality output. Examples: Laser Printer, Ink-Jet Printer, Thermal Printer.

A Dot Matrix Printer (DMP) prints by striking a matrix of tiny pins against an inked ribbon onto paper. Characters are formed as a pattern (matrix) of dots.

• Print Head: Contains 9 or 24 pins arranged in a column. A 24-pin head gives better quality (near letter quality, NLQ).
• Speed: Measured in CPS (Characters Per Second) — typically 100 to 600 CPS.
• Advantages: Can print multi-part (carbon copy) forms; low cost per page; robust and reliable.
• Disadvantages: Noisy; lower print quality compared to laser/inkjet; slow.
• Uses: Bank passbook printing, invoices, and multi-copy receipts.

4.4   Explain the Advantages and Disadvantages of D.T. Matrix Printer

• Can print on multi-layered carbon copy paper (multi-part forms) — no other printer can do this.
• Very low cost per page — ribbon cartridges are cheap.
• Robust and durable; can function in dusty and industrial environments.
• Capable of printing continuous (tractor-feed) stationery without paper jams.
• Relatively low purchase price.
• Works well in ATMs and point-of-sale (POS) terminals for receipt printing.

• Very noisy during operation — the striking of pins creates significant sound.
• Lower print quality — characters look dotty; not suitable for high-quality documents.
• Slow speed compared to laser and ink-jet printers.
• Limited graphics capability; graphics are rough and low resolution.
• Ribbon cartridges require frequent replacement for consistent print quality.
• Print head pins can break and require costly replacement.

4.5   Explain the Difference between Volatile and Non-Volatile Memories. Give One Example Each.

4.6   What do you Mean by Conventional Memory?

Conventional Memory (also known as Base Memory) refers to the first 640 KB of the RAM address space in a DOS-based PC. This was the memory region that the original IBM PC and the DOS operating system could directly address and use for running programs.

• The PC's total addressable memory in real mode is 1 MB (1024 KB).
• The first 640 KB (0x00000 – 0x9FFFF) is Conventional Memory used by DOS and application programs.
• The remaining 384 KB (0xA0000 – 0xFFFFF) is the Upper Memory Area (UMA), reserved for BIOS, video memory, and ROM.

Limitation: The 640 KB ceiling was a major bottleneck for running large applications under DOS. This led to the development of extended memory management techniques (EMS, XMS) and later, protected-mode multitasking operating systems like Windows.

5.1   State Different Types of Semiconductor Memories and Explain Any Two

Types: RAM (SRAM, DRAM), ROM (PROM, EPROM, EEPROM), Flash Memory, Cache Memory.

DRAM stores each bit of data in a tiny capacitor within an integrated circuit. Because capacitors leak charge, DRAM requires periodic refreshing (thousands of times per second) to retain data. It is volatile — loses data when power is off.

• Higher density — more bits per chip area than SRAM; used as main system RAM.
• Slower than SRAM but far cheaper and available in larger capacities.
• Modern variants: SDRAM, DDR, DDR2, DDR3, DDR4, DDR5.

SRAM stores each bit using a flip-flop circuit (4–6 transistors). It does not need refreshing as long as power is supplied. It is volatile.

• Much faster than DRAM — used as Cache Memory (L1, L2, L3).
• More expensive and lower density than DRAM.
• Consumes more power but offers very fast access times (nanoseconds).

5.2   Explain the Structure and Working of Hard Disk with Suitable Diagram

A Hard Disk Drive (HDD) is a non-volatile, magnetic secondary storage device used to store large amounts of data permanently.

• Platters: Circular disks coated with magnetic material (iron oxide or cobalt alloy). A drive may have 1–5 platters stacked on a spindle.
• Spindle: Rotates platters at high speed (5400 RPM or 7200 RPM).
• Read/Write Heads: Electromagnetic heads that float nanometers above platter surfaces to read/write data magnetically.
• Actuator Arm: Moves the read/write heads radially across the platters.
• Tracks: Concentric circular paths on each platter surface where data is written.
• Sectors: Each track is divided into sectors (usually 512 bytes or 4096 bytes each).
• Cylinders: The set of all tracks at the same radial position across all platters.
• Controller: Electronic board that controls all operations of the HDD.

1. The platters spin at high speed (5400–7200 RPM).
2. The actuator arm moves the read/write head to the required track (seek time).
3. The drive waits for the required sector to rotate under the head (rotational latency).
4. The head reads/writes data by detecting/changing the magnetic polarity of the coating.
5. Data is transferred to/from RAM via the system bus (transfer time).

Access Time = Seek Time + Rotational Latency + Transfer Time

5.3   Explain the Properties of CPU

The CPU (Central Processing Unit) is the brain of the computer. It performs all arithmetic, logical, control, and input/output operations. Its key properties are:

• Clock Speed: The speed at which the CPU executes instructions, measured in MHz or GHz. Higher clock speed = more instructions per second. Example: Intel Core i7 at 3.6 GHz.
• Word Length (Data Width): The number of bits processed simultaneously (e.g., 8-bit, 16-bit, 32-bit, 64-bit). Modern CPUs are 64-bit.
• Instruction Set: The set of machine language instructions the CPU can execute (e.g., CISC — Complex Instruction Set Computing; RISC — Reduced Instruction Set Computing).
• Register Set: Small, fast storage locations inside the CPU (e.g., Accumulator, Program Counter, Instruction Register, Stack Pointer).
• Cache Memory: High-speed memory (L1, L2, L3) built into or near the CPU to reduce memory access latency.
• Number of Cores: Modern CPUs have multiple cores (dual, quad, octa-core) to perform parallel processing.
• Arithmetic Logic Unit (ALU): Performs arithmetic (+, −, ×, ÷) and logical (AND, OR, NOT, XOR) operations.
• Control Unit (CU): Directs the operation of all other units — fetches, decodes, and executes instructions.
• Bus Interface: Connects the CPU to memory and I/O through Address, Data, and Control buses.
• Power Consumption: Measured in Watts (TDP – Thermal Design Power); lower TDP is desirable for laptops and embedded systems.

5.4   What is Meant by ROM? Explain its Types in Brief

ROM (Read Only Memory) is a type of non-volatile semiconductor memory whose contents are permanently written during manufacture or by special programming devices. Under normal computer operation, ROM can only be read — not written. It retains data even after power is switched off.

Uses of ROM: Storing BIOS/firmware, bootstrap loader, embedded system programs, and look-up tables.

• ROM (Mask ROM): Contents are permanently written during manufacturing by the chip maker. Cannot be changed by the user. Used for fixed firmware in calculators, appliances.
• PROM (Programmable ROM): Manufactured blank; can be programmed once by the user using a PROM burner. Once programmed, it cannot be erased. Fuses are permanently blown during programming.
• EPROM (Erasable Programmable ROM): Can be erased using UV light (through a quartz window) and reprogrammed. Used for BIOS chips and development. Erasing takes ~15–20 minutes.
• EEPROM (Electrically Erasable Programmable ROM): Can be erased and reprogrammed electrically, byte-by-byte, without removing from the circuit. Faster and more convenient than EPROM. Used in modern BIOS chips and smart cards.
• Flash ROM: An advanced form of EEPROM that is erased and written in blocks. Very fast, compact, and widely used in pen drives, SSDs, memory cards, and smartphones.

5.5   Explain Modem and the Use of Modem

The word MODEM stands for MOdulator-DEModulator. It is a hardware device that converts digital signals from a computer into analog signals suitable for transmission over telephone lines (Modulation), and converts incoming analog signals back to digital form (Demodulation).

• Internal Modem: Installed inside the computer as an expansion card (PCI slot).
• External Modem: Separate device connected via USB or serial port — portable and easy to configure.
• DSL Modem: Used for Digital Subscriber Line (DSL) broadband Internet.
• Cable Modem: Used for broadband internet over cable TV lines.
• Wireless Modem (Router-Modem): Provides wireless (Wi-Fi) internet connectivity.

• Connecting a computer to the Internet via telephone or broadband lines.
• Sending and receiving Fax documents over telephone lines.
• Dial-up access to Bulletin Board Systems (BBS) and remote databases.
• Enabling online communication — email, chat, video conferencing.
• Data communication between computers in different locations (WAN connectivity).
• Remote access to corporate networks (VPN over DSL/Cable).

Speed of a modem is measured in bps (bits per second) or Kbps/Mbps. A standard dial-up modem operates at 56 Kbps; DSL modems operate at several Mbps.