CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which disk-scheduling algorithm moves the head back and forth across the disk, servicing requests along the way?
A. SSTF
B. FCFS
C. Round Robin
D. SCAN
Correct Answer: D
SCAN is often called the elevator algorithm because the head sweeps in both directions.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which disk-scheduling algorithm chooses the pending request closest to the current disk-head position?
A. SSTF
B. FCFS
C. SCAN
D. FIFO page replacement
Correct Answer: A
Shortest Seek Time First reduces immediate movement but can starve distant requests.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which disk-scheduling algorithm serves requests strictly in arrival order?
A. C-SCAN
B. FCFS
C. SSTF
D. SCAN
Correct Answer: B
FCFS disk scheduling is simple and fair but may cause large head movements.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which file-allocation method uses an index block containing pointers to the file's data blocks?
A. Linked allocation only
B. Spooling
C. Indexed allocation
D. Contiguous allocation
Correct Answer: C
Indexed allocation supports direct access through a block of pointers.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which file-allocation method stores pointers that link one file block to the next?
A. Contiguous allocation
B. Pure indexed allocation
C. Paging
D. Linked allocation
Correct Answer: D
Linked allocation avoids external fragmentation but direct access is inefficient.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which allocation method stores a file in consecutive disk blocks?
A. Contiguous allocation
B. Indexed allocation
C. Linked allocation
D. Hashed allocation only
Correct Answer: A
Contiguous allocation provides fast sequential/direct access but can suffer external fragmentation and growth problems.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which link stores a pathname that points to another file or directory?
A. File descriptor
B. Symbolic link
C. Hard link
D. Page-table entry
Correct Answer: B
A symbolic link is a special file containing a path to another object.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which link creates another directory entry that refers to the same inode as the original file?
A. Shortcut file only
B. Mount point
C. Hard link
D. Symbolic link
Correct Answer: C
A hard link is another name for the same inode and file data on the same filesystem.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
In a Unix-like file system, a directory entry primarily associates:
A. A CPU core with a process
B. A virtual page with a frame
C. A user with a password hash only
D. A file name with an inode number
Correct Answer: D
Directories map names to filesystem objects represented by inode numbers.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which file-system structure stores metadata such as file size, owner, permissions, and data-block pointers in many Unix-like systems?
A. inode
B. PCB
C. TLB
D. MBR partition entry only
Correct Answer: A
An inode stores file metadata and block references; file names are stored in directory entries.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Virtual memory allows:
A. Only one process to run
B. A process address space to be larger than the amount of currently available physical RAM
C. RAM to become permanent storage
D. Every program to bypass protection
Correct Answer: B
Virtual memory uses address translation and secondary storage to present larger isolated address spaces.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Swapping refers to:
A. Changing CPU registers only
B. Encrypting a disk
C. Moving process memory between RAM and secondary storage
D. Moving a file between folders
Correct Answer: C
Swapping frees RAM by transferring process memory to backing storage and later restoring it.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which memory technique may combine segmentation and paging?
A. Spooling
B. Disk mirroring
C. Batch scheduling
D. Paged segmentation
Correct Answer: D
Some systems page individual segments to combine logical segmentation with fixed-size physical allocation.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Segmentation divides a program according to:
A. Logical variable-sized units such as code, data, and stack
B. Fixed-size physical tracks
C. CPU time quanta
D. Network packets only
Correct Answer: A
Segmentation reflects logical program structure and therefore uses variable-size segments.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Paging largely eliminates which memory-allocation problem?
A. Address translation
B. External fragmentation
C. All internal fragmentation
D. Page faults
Correct Answer: B
Fixed-size pages and frames remove the need for contiguous physical allocation, avoiding external fragmentation.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which type of fragmentation consists of free memory broken into small noncontiguous holes?
A. Packet fragmentation
B. Page coloring
C. External fragmentation
D. Internal fragmentation
Correct Answer: C
External fragmentation makes total free memory available but not as one large contiguous block.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which type of fragmentation consists of wasted space inside allocated fixed-size blocks?
A. External fragmentation
B. Network fragmentation
C. File-name fragmentation
D. Internal fragmentation
Correct Answer: D
Internal fragmentation is unused space within an allocated unit such as a page or fixed partition.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
The working-set concept is used to estimate:
A. The set of pages a process is actively using
B. All files on a disk
C. The number of CPU cores
D. User passwords
Correct Answer: A
Working-set models help allocate enough frames to keep active process pages resident.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Thrashing occurs when:
A. Only one page is used
B. The system spends excessive time paging instead of executing useful work
C. The disk is freshly formatted
D. The CPU has no processes
Correct Answer: B
High page-fault activity can dominate execution and collapse effective performance.
CSS - PMS - CCE - PCS - Basic Computing
Operating Systems
Which page-replacement algorithm may show Belady's anomaly?
A. Optimal
B. Stack algorithms only
C. FIFO
D. LRU
Correct Answer: C
With FIFO, adding more frames can paradoxically increase page faults for some reference strings.