Model Question Paper

Concept: Memory hierarchy organises storage from fastest-smallest-expensive (top) to slowest-largest-cheap (bottom).

Levels of Hierarchy:

1. Level 0 — CPU Registers: Tiny (32–64 bit) storage inside the CPU. Access time: <1 ns. Example: EAX, EBX in x86.
2. Level 1 — Cache (L1/L2/L3): SRAM on or near the CPU die.
3. Level 2 — Main Memory (RAM): DRAM, GBs in size, holds the active OS.
4. Level 3 — Secondary Storage (SSD/HDD): Non-volatile, TBs, millisecond access.
5. Virtual Memory: Uses part of the SSD/HDD as an extension of RAM.

• Speed: SSDs use NAND flash with no moving parts — sequential read up to 550 MB/s (SATA) or 7000 MB/s (NVMe) vs ~150 MB/s for HDD.
• Access time: SSD random access ~0.1 ms vs HDD ~10 ms.
• Durability: No mechanical parts means SSDs withstand shock, vibration, and drops much better.
• Silent operation: No spinning platters or moving heads — completely silent.
• Power efficiency: SSDs consume less power.

Major components on a motherboard: CPU socket, RAM slots (DIMM), chipset, PCIe slots, SATA connectors, M.2 slot, ROM chip.

Roles of three key components:

1. CPU Socket: Physically mounts and electrically connects the processor to the board. A high-quality socket with good power delivery ensures the CPU can boost to its maximum frequency reliably.
2. RAM Slots (DIMM): Hold DDR4/DDR5 memory modules. Dual-channel configurations double memory bandwidth, reducing bottlenecks for CPU-intensive workloads.
3. PCH / Chipset: Acts as the traffic controller between CPU, RAM, storage, USB, PCIe devices. Manages I/O bandwidth allocation.

Definition: A bus is a set of parallel conductors (wires/traces on PCB) that carry data, addresses, and control signals between computer components.

• Data Bus: Carries the actual data being transferred.
• Address Bus: Carries the memory address specifying the source or destination of data.
• Control Bus: Carries control signals (Read/Write, Interrupt, Clock) that co-ordinate operations.

Example: Add 0101 (5) and 0011 (3). Expected result: 1000 (8).

• Step 1 — Bit 0 (LSB): 1 + 1 = 10 -> sum bit = 0, carry = 1
• Step 2 — Bit 1: 0 + 1 + carry(1) = 10 -> sum bit = 0, carry = 1
• Step 3 — Bit 2: 1 + 0 + carry(1) = 10 -> sum bit = 0, carry = 1
• Step 4 — Bit 3 (MSB): 0 + 0 + carry(1) = 01 -> sum bit = 1, carry = 0

Result: 1000 (binary) = 8 (decimal). The carry-out from bit 3 is 0, so no overflow.

• (i) Control Unit: Directs the operation of the processor. It coordinates the fetch-decode-execute cycle. It reads instructions from the instruction register, decodes them, and sends control signals to the ALU and memory to execute the instruction.
• (ii) Instruction Set (ISA): The complete set of machine-level instructions that a CPU can execute. It facilitates software-hardware interaction by acting as the contract between hardware designers and software compilers. High-level code (C, Java) is compiled into these specific ISA instructions, which the CPU's hardwired circuits physically execute directly.

• Scope of characters: ASCII supports only 128 characters (7-bit), sufficient for English but inadequate for global applications. Unicode (version 15) defines over 149,000 characters spanning 161 scripts — Latin, Arabic, Devanagari, CJK ideographs, and emoji.
• UTF-8 encoding: The most common Unicode encoding. fully backward compatible with ASCII. Uses 1 byte for ASCII-compatible characters, 2–4 bytes for others.
• Internationalisation (i18n): Multilingual apps must display user interfaces, store user data, and process input in any language. Unicode provides a single unified standard, eliminating the need for multiple encoding systems.

Steps to represent -12:

1. Find binary for positive 12: 0000 1100
2. Perform 1's complement (invert the bits): 1111 0011
3. Add 1 (2's complement): 1111 0011 + 1 = 1111 0100 Result: -12 is represented as 1111 0100 in 8-bit 2's complement.

Representing 255: To represent the number 255 in binary (1111 1111), 8 bits are required.

• Client-Server Network: A dedicated server provides resources/services; clients request them. The server handles authentication, access control, storage, and backups centrally.
  • Advantages: Centralised security, easy to scale, reliable data backup, audit logging.
  • Disadvantages: Higher cost (server hardware), single point of failure (if not redundant).
• Peer-to-Peer (P2P) Network: Each device acts as both client and server.
  • Advantages: Low cost, easy to set up for small groups.
  • Disadvantages: Decentralised security, difficult to scale, hard to manage.
• Recommendation: Client-Server is far better for a multi-city company due to centralized management, reliable backups, and consistent security features.

• (i) Create a directory: mkdir (e.g., mkdir reports)
• (ii) List files and subfolders: ls -la (lists all including hidden, with long format showing permissions)
• (iii) Copy contents: cp (e.g., cp file.txt backup/)
• (iv) Change access permissions: chmod (e.g., chmod 755 script.sh)

• Desktop Security: (1) Install antivirus/anti-malware on all endpoints. (2) Enable OS auto-updates and patch management. (3) Enforce strong password policies and multi-factor authentication (MFA). (4) Use disk encryption (BitLocker) for stolen laptops.
• Perimeter Security: (1) Deploy a Next-Generation Firewall (NGFW) at the network boundary to inspect traffic. (2) Set up a DMZ for public-facing servers. (3) Use Intrusion Detection/Prevention Systems (IDS/IPS). (4) Implement DNS filtering.
• VPN for Remote Access: Deploy a VPN gateway (e.g., OpenVPN) that remote employees connect to before accessing internal systems. All traffic is encrypted (AES-256). Require MFA for VPN login.

Client-Server Network: A network model where one or more powerful computers (servers) provide services, and many other computers (clients) consume those services. Communication is always client-initiated.

• Real-world example — Web browsing: Your browser (client) sends an HTTP GET request to Google's web server. Google's server processes the request and sends back HTML/CSS/JS.

Role of DNS:

• DNS (Domain Name System) is the internet's phonebook. Humans use domain names (google.com); computers communicate using IP addresses (142.250.77.46). DNS translates domain names to IPs.
• Why DNS matters: Without DNS, users would have to memorise IP addresses for every website. DNS also enables load balancing and failover.

<!DOCTYPE html>
<html>
<head>
  <title>BookNook Online Bookstore</title>
  <style>
    body { font-family: sans-serif; background-color: #f4f4f9; padding: 20px; }
    header { background-color: #2c3e50; color: white; padding: 15px; text-align: center; }
    ul { list-style-type: square; color: #333; margin-top: 20px; }
    li { padding: 5px 0; }
    .container { max-width: 800px; margin: auto; background: white; padding: 20px; border-radius: 8px; }
  </style>
</head>
<body>
  <div class="container">
    <header>
      <h1>Welcome to BookNook</h1>
    </header>
    <h2>Book Categories</h2>
    <ul>
      <li>Science Fiction & Fantasy</li>
      <li>Mystery & Thriller</li>
      <li>Biography & Autobiography</li>
      <li>Computers & Technology</li>
    </ul>
  </div>
</body>
</html>

Original errors corrected:

1. Improper tag nesting: <b><i>Some text</b></i> — inner <i> tag must close before outer <b>.
2. Uppercase tags: <BODY>, <P> — XHTML requires all element names to be lowercase.
3. Uppercase attribute: HREF — XHTML requires lowercase attributes.

Corrected XHTML:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head></head>
<body>
  <b><i>Some text</i></b>
  <p>This is a paragraph</p>
  <a href="https://www.ktu.edu.in/">Visit our university website</a>
</body>
</html>

Approach: JavaScript's setInterval() function repeatedly executes a callback every 1000 ms. On each call, the current time is subtracted from the event date to compute remaining days, hours, minutes, and seconds.

<div id="timer">Loading...</div>
<script>
  const eventDate = new Date('2025-12-01T09:00:00').getTime();
  
  function updateCountdown() {
    const now = new Date().getTime();
    const diff = eventDate - now;
    
    if (diff <= 0) {
      document.getElementById('timer').innerHTML = 'Event has started!';
      return;
    }
    
    const days = Math.floor(diff / (1000 * 60 * 60 * 24));
    const hours = Math.floor((diff % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
    const minutes = Math.floor((diff % (1000 * 60 * 60)) / (1000 * 60));
    const seconds = Math.floor((diff % (1000 * 60)) / 1000);
    
    document.getElementById('timer').innerHTML = 
      `${days}d ${hours}h ${minutes}m ${seconds}s`;
  }
  
  updateCountdown();
  setInterval(updateCountdown, 1000);
</script>

1. Inline CSS: Style is applied directly to a single HTML element using the style attribute. Highest specificity.

<p style="color: red; font-size: 16px;">Inline styled paragraph</p>

2. Internal (Embedded) CSS: CSS rules are placed inside a <style> tag in the <head> section. Applies to that page only.

<style>
  p { color: blue; font-size: 14px; }
</style>

3. External CSS: CSS rules are written in a separate .css file and linked using <link>. Best practice for multi-page websites.

<!-- In HTMLhead -->
<link rel="stylesheet" href="styles.css">