Q.1 Which of the following is NOT an I/O device?
Keyboard
Mouse
CPU
Printer
Explanation - The CPU is a processing unit, not an input/output device. Input/output devices are peripherals like keyboard, mouse, or printer.
Correct answer is: CPU
Q.2 What does 'spooling' in operating systems mean?
Simultaneous Peripheral Operations On-Line
Single Peripheral Output Line
Serial Port Operation Linked
Shared Peripheral Output Layer
Explanation - Spooling stands for Simultaneous Peripheral Operations On-Line, which allows multiple I/O jobs to be queued for devices like printers.
Correct answer is: Simultaneous Peripheral Operations On-Line
Q.3 In device management, what is the main role of a device driver?
Manage user processes
Translate OS commands to device commands
Handle memory allocation
Perform CPU scheduling
Explanation - Device drivers act as translators between the operating system and hardware devices, enabling proper communication.
Correct answer is: Translate OS commands to device commands
Q.4 Which type of I/O technique requires the CPU to continuously check device status?
Interrupt-driven I/O
DMA
Programmed I/O
Spooling
Explanation - In programmed I/O, the CPU constantly checks device status, leading to inefficient use of processing power.
Correct answer is: Programmed I/O
Q.5 What is the full form of DMA?
Direct Memory Allocation
Direct Memory Access
Dynamic Memory Access
Data Management Algorithm
Explanation - DMA stands for Direct Memory Access, allowing devices to access system memory directly without CPU intervention.
Correct answer is: Direct Memory Access
Q.6 Which of the following I/O methods reduces CPU involvement the most?
Programmed I/O
Interrupt-driven I/O
DMA
Polling
Explanation - DMA allows direct transfer of data between devices and memory, minimizing CPU intervention.
Correct answer is: DMA
Q.7 What is an example of a block device?
Keyboard
Mouse
Hard Disk
Scanner
Explanation - Hard disks transfer data in fixed-size blocks, making them block devices, unlike keyboards or mice which are character devices.
Correct answer is: Hard Disk
Q.8 Which of the following is a character device?
CD-ROM
Printer
Hard Disk
Keyboard
Explanation - Character devices transmit data one character at a time, like keyboards or printers.
Correct answer is: Keyboard
Q.9 In I/O systems, buffering is mainly used to:
Speed up CPU
Match speed differences between producer and consumer
Reduce RAM usage
Eliminate device drivers
Explanation - Buffering helps match the speed of fast CPUs with slower I/O devices, ensuring smooth data flow.
Correct answer is: Match speed differences between producer and consumer
Q.10 Which I/O technique uses signals to notify the CPU that a device needs attention?
Programmed I/O
Interrupt-driven I/O
Polling
DMA
Explanation - Interrupt-driven I/O uses hardware interrupts to signal the CPU, reducing busy waiting.
Correct answer is: Interrupt-driven I/O
Q.11 The disk scheduling algorithm that minimizes seek time is:
FCFS
SSTF
Round Robin
LIFO
Explanation - SSTF (Shortest Seek Time First) selects the request closest to the current head position, minimizing seek time.
Correct answer is: SSTF
Q.12 Which disk scheduling algorithm may cause starvation?
FCFS
SSTF
SCAN
C-SCAN
Explanation - SSTF may cause starvation for requests far from the current head position since nearer requests are always prioritized.
Correct answer is: SSTF
Q.13 What does SCAN disk scheduling algorithm also called?
Elevator algorithm
First Come First Serve
Circular Queue
Greedy Algorithm
Explanation - SCAN is called the Elevator algorithm since the disk arm moves back and forth like an elevator servicing requests.
Correct answer is: Elevator algorithm
Q.14 Which scheduling algorithm ensures uniform wait time across requests?
SSTF
FCFS
SCAN
C-SCAN
Explanation - C-SCAN provides uniform wait time as the disk arm only moves in one direction before resetting.
Correct answer is: C-SCAN
Q.15 What is the primary function of an I/O control system?
Scheduling CPU processes
Managing device communication
Providing network services
Memory allocation
Explanation - The I/O control system manages communication between hardware devices and the OS.
Correct answer is: Managing device communication
Q.16 Which device requires isochronous data transfer?
Printer
Hard Disk
Microphone
Keyboard
Explanation - Isochronous transfer ensures timely delivery of streaming data like audio from a microphone.
Correct answer is: Microphone
Q.17 What does 'spooling' commonly apply to?
Disk scheduling
Printer management
Memory allocation
Network communication
Explanation - Spooling is commonly used in printers to queue multiple jobs efficiently.
Correct answer is: Printer management
Q.18 Which component signals the CPU when an I/O operation is complete?
Buffer
Cache
Interrupt controller
Scheduler
Explanation - The interrupt controller signals the CPU that an I/O device has completed its task.
Correct answer is: Interrupt controller
Q.19 In I/O systems, what is 'latency'?
Time to transfer data
Time delay before transfer begins
CPU processing speed
Amount of memory used
Explanation - Latency refers to the initial delay before data transfer starts in I/O operations.
Correct answer is: Time delay before transfer begins
Q.20 What is 'throughput' in I/O systems?
Data transfer rate per unit time
Time delay in I/O request
Number of interrupts
Amount of CPU usage
Explanation - Throughput is the amount of data transferred per unit time in an I/O system.
Correct answer is: Data transfer rate per unit time
Q.21 Which of these is NOT an objective of device management?
Fair allocation of devices
Device independence
Deadlock prevention
Improving CPU clock speed
Explanation - Device management ensures fairness, independence, and prevents deadlocks, but CPU clock speed is unrelated.
Correct answer is: Improving CPU clock speed
Q.22 In DMA, the CPU is interrupted:
After every byte transfer
After the whole block transfer
Continuously during transfer
Never
Explanation - In DMA, the CPU is only interrupted once after the entire block transfer is complete.
Correct answer is: After the whole block transfer
Q.23 What does 'device independence' mean in OS?
Users write code specific to devices
OS hides device details from users
Devices can work without drivers
Devices have no interrupts
Explanation - Device independence allows the OS to hide hardware-specific details so programs can run on different devices.
Correct answer is: OS hides device details from users
Q.24 What is the main disadvantage of polling?
Simple to implement
Consumes CPU time unnecessarily
Requires hardware interrupts
Difficult to program
Explanation - Polling wastes CPU cycles as it keeps checking device status repeatedly.
Correct answer is: Consumes CPU time unnecessarily
Q.25 Which I/O method is best for high-speed devices?
Programmed I/O
Polling
Interrupt-driven I/O
DMA
Explanation - DMA is ideal for high-speed devices as it transfers data directly between memory and device without burdening the CPU.
Correct answer is: DMA