Basics of OS

Question 1

What is an Operating System?

Answer 1

An Operating System is an interface between computer hardware and computer users.
Manages memory, file, process and controls peripheral devices(printer).

Question 2

What are the different operating systems?

Answer 2

Batch, real-time, distributed, time-sharing, Multiprogrammed.

Question 3

What is a socket in OS?

Answer 3

A software construct which allows two applications to communicate with each other.

Question 4

Batch Operating System?

Answer 4

batching/ grouping the jobs which have the same requirements.

Question 5

Time-Sharing Operating Systems?

Answer 5

CPU time is shared among the users.
this operating system is also known as multitasking operating system.

Question 6

Distributed os?

Answer 6

multiple computers connected together using a shared connection .

Question 7

What is a kernel

Answer 7

It is the core of OS. it acts as an intermediate between the software applications and the hardware

Question 8

types of kernel

Answer 8

monolithic, micro, exo , hybrid, Nano

Question 9

monolithic kernel

Answer 9

A monolithic kernel in an operating system is a kernel that includes all operating system code in a single executable image.
eg: linux, unix
that means kernel handles all the functions of os.

Question 10

what is a process

Answer 10

Program under execution is known as process.

Question 11

What is aging in the Operating System?

Answer 11

Aging is a technique which helps in avoiding starvation in the resource scheduling system. Starvation occurs when a process is unable to get the resources it needs to run, even though it is waiting for those resources. Aging works by increasing the priority of a process that has been waiting for a long time. This means that the process is more likely to be scheduled to run, even if it has a lower priority than other processes.

Question 12

What are the different scheduling algorithms in OS?

Answer 12

First-Come, First-Served (FCFS) Scheduling, Shortest-Job-Next (SJN) Scheduling, Priority Scheduling, Shortest Remaining Time, Round Robin(RR) Scheduling, Multiple-Level Queues Scheduling.

Question 13

what is a thread

Answer 13

it is a light weight process, it allows to divide the process into multiple threads and achieve parallelism.

Question 14

what is context switching.

Answer 14

to switch between the tasks rapidly when one of process goes into the wait state.

Question 15

multitasking os, multi-programming os, multi-processing os.

Answer 15

multi-tasking OS contains only one cpu and process are allowed to execute only for a particular time quantum.
multi-programming
single cpu with ready queue for process execution.
multi-processing :
has more than one cpu , context switching, time sharing, backup cpu’s.

Question 16

How communication takes place between the user mode and the kernel mode.

Answer 16

with the help of IPC(inter process communication)

Question 17

how do we switch from user mode to kernel mode and how do apps interact with the kernel.

Answer 17

we use system interrupt to switch from kernel mode to user mode and we use system calls to send messages to kernel to carry out a task

Question 18

what are the major steps that takes place when you switch on your system.

Answer 18

• power supplied to all hardware.
• boot process, BIOS starts
• boot device(ssd or hdd) and the boot loader turn on the actual os.
  -MBR lies on the 0th index it starts

Question 19

types of storage

Answer 19

primary: register, cache, main memory
secondary : electronic disk, magnetic disk, optical disk and magnetic tapes

Question 20

what is stored in PCB

Answer 20

process control block has process id , program counter, process state, priority, register, open file list and open device list.

Question 21

states of a process

Answer 21

new, ready, run, wait, termination, suspended wait, suspended ready.