File system-I/O-protection

Question 1

The index node (inode) of a Unix-like file system has 12 direct, one single-indirect and one double-indirect pointers. The disk block size is 4 kB, and the disk block address is 32-bits long. The maximum possible file size is (rounded off to 1 decimal place) ______ GB.

A
7.0
B
9.0
C
2.0
D
4.0
       Operating-Systems       File system-I/O-protection       GATE 2019       Video-Explanation
Question 1 Explanation: 
No. of Disk block pointers = 4kB/32bits = 1k
Max. file size
= (12 × 1k + 1k × 1k) × 4kB
≈ (1024 × 12 + 1024 × 1024) × 4 × 1024 bytes
≈ 4GB
Question 2

Normally user programs are prevented from handling I/O directly by I/O instructions in them. For CPUs having explicit I/O instructions, such I/O protection is ensured by having the I/O instructions privileged. In a CPU with memory mapped I/O, there is no explicit I/O instruction. Which one of the following is true for a CPU with memory mapped I/O ?

A
I/O protection is ensured by operating system routines.
B
I/O protection is ensured by a hardware trap.
C
I/O protection is ensured during system configuration.
D
I/O protection is not possible.
       Operating-Systems       File system-I/O-protection       UGC-NET CS 2018 JUNE Paper-2
Question 2 Explanation: 
→ I/O protection can be ensured by operating system. Because all the user application are not modified by user mode. Those are sent to kernel mode as a system calls.
→ Normally user programs are prevented from handling I/O directly by I/O instructions in them , For CPUs having explicit I/O instructions, such I/O protection is ensured by having the I/O instruction privileged.
Question 3
Which of the following is not an input device?
A
Mouse
B
Keyboard
C
Light Pen
D
VDU
       Operating-Systems       File system-I/O-protection       Nielit Scientist-B IT 4-12-2016
Question 3 Explanation: 
→ Mouse,​ Keyboard and Light Pen are input devices.
→ Computer monitors were formerly known as ​ visual display units​ (​ VDU​ ), but this term had mostly fallen out of use by the 1990s.
Question 4
The file manager is responsible for
A
naming files
B
saving files
C
deleting files
D
all the above
       Operating-Systems       File system-I/O-protection       Nielit Scientist-C 2016 march
Question 4 Explanation: 
● A file manager is a software program that helps a user manage all the files on their computer. For example, all file managers allow the user to view, edit, copy, and delete the files on their computer storage devices.
● Note: Although a file manager helps the user view and manage their files, it is the operating system that is responsible for accessing and storing the files on a storage device.
Question 5
The file structure that redefines its first record at a base of zero uses the term
A
relative organization
B
key fielding
C
dynamic reallocation
D
all of these
       Operating-Systems       File system-I/O-protection       Nielit Scientist-B CS 2016 march
Question 5 Explanation: 
● A relative record file contains records ordered by their relative key, a record number that represents the location of the record relative to where the file begins.
● For example, the first record in a file has a relative record number of 1, the tenth record has a relative record number of 10, and so forth. The records can have fixed length or variable length.
There are 5 questions to complete.

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