Operating System Concepts Quiz

Operating System Types

• Multitasking OS: Allows a single user to execute multiple programs concurrently.
• Real-time OS: Designed for applications with strict timing requirements, such as industrial control systems.
• Distributed OS: Manages a network of computers, enabling resource sharing and communication.
• Network OS: Provides network services to users and computers, including file sharing and printing.

Disk Scheduling Algorithms

• FCFS (First Come First Served): Processes disk requests in the order they arrive.
• Shortest Seek Time First (SSTF): Selects the request closest to the current head position.
• SCAN (Elevator Algorithm): Moves the disk head in one direction, servicing requests along the way.
• C-SCAN (Circular SCAN): Similar to SCAN, but wraps around to the beginning of the disk after reaching the end.

Disk Space Management

• Linked List Allocation: Maintains a linked list of free blocks, allowing quick allocation and deallocation of disk space.
• Bit-vector Allocation: Uses a bit vector to track the status of each block, where a 1 represents an allocated block and a 0 represents a free block.

Process Control Block (PCB)

• Purpose: Stores information about a process, including its state, memory usage, and resources.
• Information Stored: Process ID, program counter, CPU registers, memory allocation, file descriptors, and accounting information.

Memory Management

• Internal Fragmentation: Occurs when a memory block is allocated but not fully utilized, leaving unused space within the block.
• External Fragmentation: Occurs when free memory is scattered across multiple small blocks, making it difficult to allocate larger blocks.

Paging and Segmentation

• Paging: Divides physical memory into fixed-sized pages and logical memory into equal-sized frames.
• Segmentation: Divides logical memory into variable-sized segments, allowing for better memory management for programs with differing memory requirements.

Process States

• New: Process is being created.
• Ready: Process is waiting to be assigned to the CPU.
• Running: Process is currently executing on the CPU.
• Waiting: Process is waiting for an event to occur, such as I/O completion.
• Terminated: Process has completed execution.

File Systems

• Hierarchical File System: Organizes files in a tree-like structure, with a root directory at the top and subdirectories branching out.

Memory Allocation Strategies

• First-Fit: Allocates the first free block that is large enough to accommodate the request.
• Best-Fit: Allocates the smallest free block that can satisfy the request.
• Worst-Fit: Allocates the largest free block, leaving the largest remaining free block for future requests.

File Access Methods

• Sequential Access: Reads data in a linear order, from the beginning to the end of the file.
• Direct Access: Allows for retrieving data at any specific location within the file, without reading sequentially.

Swapping

• Purpose: Moves inactive processes from RAM to secondary storage (disk), freeing up memory for active processes.

Resource Sharing

• Processes can share resources, such as files, printers, and databases, through mechanisms like shared memory and semaphores.

Process Control Block (PCB) Functions

• Process identification and management: Provides information about a process, including its ID, state, and priority.

Firewalls

• Purpose: Act as a barrier between a private network and the outside world, controlling network traffic and blocking unauthorized access.

Memory Management Fragmentation

• Internal Fragmentation: Memory block allocated but not fully used.
• External Fragmentation: Small free memory blocks scattered, making allocating larger blocks harder.

Process Synchronization

• Critical Section: Code segment that must be accessed by only one process at a time to avoid data corruption.
• Mutual Exclusion: Ensures that multiple processes do not access the same shared resource concurrently.
• Semaphore: A synchronization primitive used to control access to shared resources, allowing a limited number of processes to enter a critical section.

Process Synchronization Concepts

• Starvation: Occurs when a process is repeatedly denied access to resources for an extended period, despite being eligible.

Access Control Lists (ACLs)

• Purpose: Defines specific permissions for accessing resources, such as files and directories.

Security Concepts

• Authentication: Verifying the identity of a user or process.
• Authorization: Determining what resources a user or process is allowed to access.
• Encryption: Transforming data into an unreadable format to secure data transmission.
• Integrity: Ensuring that data remains unmodified and accurate.
• Availability: Ensuring that resources are accessible when needed.

Semaphores

• Purpose: Used to control access to shared resources by implementing a counter that represents the number of available resources.
• Operations: A process can acquire a semaphore resource, decreasing the counter, or release it, increasing the counter.

Test your knowledge on operating system fundamentals including definitions, components, and various types of operating systems. This quiz covers services, scheduling algorithms, disk management, and page faults. Additionally, it includes process scheduling techniques and file allocation strategies.