1. Translation Lookaside Buffer (TLB)
TLB is a small, fast memory inside the CPU that stores recently used page table entries. Instead of checking the page table every time, the CPU first checks the TLB. If the entry is found (TLB hit), it saves time and speeds up memory access.
2. Segmentation and modular programming
Segmentation divides a program into logical parts like functions, arrays, or stack. Each part is stored separately in memory. This makes programs easier to organize, develop, and debug because each module can be handled independently.
3. Solid State Disk (SSD)
An SSD is a storage device that uses flash memory (like a pen drive) instead of spinning disks. Since it has no moving parts, it is faster, quieter, and more reliable than a traditional hard disk.
4. Contiguous vs Linked allocation
In contiguous allocation, all file blocks are stored next to each other, so access is fast but it wastes space due to fragmentation.
In linked allocation, file blocks are stored anywhere in the disk and connected using pointers, so it avoids fragmentation but access becomes slower.
5. Partitioning in disk management
Partitioning means dividing a hard disk into smaller sections called partitions. Each partition acts like a separate disk, helping in better data organization, easier backup, and even running multiple operating systems.
6. Steps in handling a page fault
When a required page is not in memory:
CPU detects missing page (page fault)
OS checks if the request is valid
Finds a free space (frame) in memory
Loads the page from disk into memory
Updates the page table
Restarts the interrupted instruction
7. Two disk scheduling algorithms
FCFS (First Come First Serve) handles requests in the order they arrive. It is simple but may be slow.
SSTF (Shortest Seek Time First) selects the request closest to the current position, reducing movement and improving speed.
8. Seek time
Seek time is the time taken by the disk arm to move from its current position to the required track where data is stored. Less seek time means faster performance.
9. File attributes
File attributes are details about a file, such as its name, size, type, location, access permissions, and creation or modification time. These help the OS manage and identify files.
10. File protection
File protection ensures that only authorized users can access or modify a file. It defines permissions like read, write, and execute to keep data safe.
11. Purpose of page tables
Page tables are used to map virtual (logical) addresses to physical memory addresses. They help the operating system keep track of where each page is stored in memory.
12. Fixed vs Variable partitioning
In fixed partitioning, memory is divided into fixed-size blocks. It is simple but may waste space.
In variable partitioning, memory is allocated based on process size, which uses space better but can lead to fragmentation.
13. Segmentation for modular design
Segmentation allows a program to be divided into smaller logical units (modules). Each module can be developed and managed separately, making the program more organized and flexible.
14. FCFS vs SSTF
FCFS processes requests in order, so it is fair but may take more time.
SSTF chooses the nearest request, reducing seek time and improving speed, but some requests may wait longer (starvation).
15. File extensions
File extensions (like .txt, .jpg, .exe) tell the operating system what type of file it is and which application should be used to open it.