Practice Questions

Duration: 4 min

This video lesson is available to enrolled students.

Return to /learn/BIHAR-POLYTECHNIC-LECTURER-COMPUTER-SCIENCE/paper-1-computer-organization-and-architecture/input-output-organisation/disk-access-time-performance/asset-practice-questions-1955 after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. Discrete Mathematics: Permutation, Combination and Probability / क्रमचय, संचय एवं प्रायिकता, Set Theory, Relations, Functions, Propositional and Predicate Logic, Graph Theory, Group Theory
  2. Digital Logic: Digital Systems & Boolean Basics, Boolean Expression, Boolean Minimization, Logic Gates & Hardware, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep
  3. Computer Organization and Architecture: Basics of COA, Programming the Basic Computer, Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Register Transfer and Microoperations, Control Unit Design, Pipelining, Multiprocessors
  4. Programming: Language Design, C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, OOPS with C++
  5. Data Structures: Introduction to DS, Array, Linked List, Stack, Queue, Tree, Graphs, Hashing
  6. Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  7. Theory of Computation: Grammar, Regular Language Properties, Moore & Mealy Machines, Turing Machines
  8. Compiler Design: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization, Run Time Environment, Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Pushdown Automata & CFG, Complexity Theory
  9. Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Unix OS, Linux OS, Security
  10. Database Management Systems: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Relational Calculus, Transaction Management, Concurrency Control, ORDBMS, NoSQL
  11. Computer Networks: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Security
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The lecture focuses on calculating the total time required to transfer a file stored on a disk, specifically comparing contiguous and non-contiguous allocation strategies. The problem provides specific disk parameters: 8 sectors per track, 512 bytes per sector, a rotation speed of 3000 rpm, and an average seek time of 15ms. The file size is defined as requiring 8 sectors. The instructor systematically breaks down the components of disk access time: Seek Time (ST), Rotational Latency (RL), and Transfer Time (TT). He demonstrates the calculation for non-contiguous allocation, where each sector requires a separate seek and latency operation, contrasting it with the efficiency of contiguous allocation where data is stored sequentially.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the problem statement visible on the screen, which asks for the total time to transfer a file requiring 8 sectors. He begins by analyzing part (b) Non-contiguous allocation. He writes the general formula for total time as the sum of Seek Time (ST), Rotational Latency (RL), and Transfer Time (TT). He then calculates the Rotational Latency based on the 3000 rpm speed. He converts rpm to rotations per second (3000/60 = 50) and determines the time for one full rotation (1000ms/50 = 20ms). Consequently, the average rotational latency is half of that, which he writes as 10ms on the board. He explicitly writes "10 ms" under the RL term in his formula.

  2. 2:00 – 3:36 02:00-03:36

    Continuing with the non-contiguous allocation calculation, the instructor explains that since the file requires 8 sectors and they are non-contiguous, the disk head must seek and wait for rotation for each sector individually. He writes the expression 8 (15ms + 10ms), representing 8 times the sum of seek time (15ms) and rotational latency (10ms). He then calculates the Transfer Time (TT). Since there are 8 sectors per track and the file is 8 sectors, the transfer time equals the time for one full rotation, which is 20ms. He writes 8/8 * 20ms = 20ms. Finally, he sums the components: 8 * 25ms + 20ms, resulting in a total time of 220ms. He writes "220ms" as the final answer on the board.

The lesson effectively demonstrates how disk allocation strategies impact performance. By calculating the time for non-contiguous allocation, the instructor highlights the overhead of multiple seek and latency operations. The final result of 220ms serves as a concrete example of the inefficiency compared to contiguous allocation, where the seek and latency would only occur once. This reinforces the importance of file system design in optimizing I/O operations.

Loading lesson…