Operating Systems

Question 1

What is the Operating System?

Answer 1

Interface between end user and computer hardware. Manages hardware and software resources. It also manages memory and security.

Question 2

What are the types of Operating Systems?

Answer 2

Batch OS, Multiprogramming OS, Multitasking OS, Time Sharing OS, Real Time OS

Question 3

What is a Batch OS?

Answer 3

Similar jobs are stored in main memory for execution. A job gets assigned to the CPU only when previous job is complete.

Question 4

What is Multiprogramming OS?

Answer 4

Allows quick switches between jobs so the user can interact with each program as it runs. The main memory consists of jobs waiting for CPU time. The OS selects one of the processes and assigns it to the CPU. Whenever the executing process needs to wait for any operation, the OS selects another process from the job queue and assigns it to the CPU.

Question 5

What is Multitasking OS?

Answer 5

Multitasking OS combines the benefits of Multiprogramming OS and CPU scheduling to perform quick switches between jobs. The switch is so quick that the user can interact with each program as it runs.

Question 6

What is Real Time OS?

Answer 6

Real Time OS are usually built for dedicated systems to accomplish a specific set of tasks within deadlines.

Question 7

What are the benefits of an OS?

Answer 7

Simplifies and abstracts everything for user. User doesn’t have to worry about the finer details.

Question 8

What can an Operating System do?

Answer 8

Enable/allow software to run. Provide a disk file system and a way to navigate it. Handles hardware devices. Provides a user interface (or GUI).

Question 9

What are the 4 classes of Operating Systems?

Answer 9

Desktop, Server, Mobile and Real Time

Question 10

What is the Desktop class?

Answer 10

Multi-user, UI, user focused

Question 11

What is the Server class?

Answer 11

For services, 24/7, not intended for users directly

Question 12

What is the Mobile class?

Answer 12

1 user, smaller screen and battery focused

Question 13

What is the Real Time class?

Answer 13

Embedded, event driven, no keyboard, mouse or screen

Question 14

What is a Family Tree?

Answer 14

The Family Tree of Operating Systems e.g. Windows 95, 98, ME or Windows NT/2000/XP/Vista/7/8/10, etc.

Question 15

What is the Kernal?

Answer 15

The Kernal is the heart of the Operating System and communicates with user interfaces, OS applications, 3rd party applications, drivers and therefore I/O devices, IO, CPU and Memory, etc.

Question 16

What is the ultimate goal of an Operating System?

Answer 16

Efficient running of application software.

Question 17

What is Multitasking?

Answer 17

Multitasking is when the OS runs more than one piece of software at the same time e.g. using Word while listening to music. Managed by the Scheduler.

Question 18

What is the Scheduler?

Answer 18

The Scheduler is part of the Kernal and is software that schedules the processes in the Operating System. it helps keeps computer resources busy and efficient.

Question 19

What are Device Drivers?

Answer 19

Device Drivers allow the Operating System and a device communicate. The handle low-level details of instructing hardware in specific ways as defined by manufacturers.

Question 20

How do Operating Systems manage memory?

Answer 20

The Operating System manages the computer’s memory (RAM). Each program must have its own section of memory and be protected from running other programs.

Question 21

What is Virtual Memory?

Answer 21

Virtual Memory is used when there is not enough real memory to hold all the running software. It is a technique where secondary memory is used as if it were part of the main memory. Compensates for physical memory shortages, temporarily transferring data from RAM to disk storage.

Question 22

How do Operating Systems manage Security?

Answer 22

A key function of the Operating System is to protect applications against a range of malicious attacks such as unauthorized access to privileged information, tempering with executable code and spoofing.

Question 23

What is “Swapping” in Virtual Memory?

Answer 23

The exchange of data to and from a disk.Wha

Question 24

What are the advantages of Virtual Memory?

Answer 24

Allows the loading of applications bigger than memory. It extends memory to the disk.

Question 25

What are the disadvantages of Virtual Memory?

Answer 25

Virtual Memory systems are slower than pure RAM. There is some overhead for doing the swapping.

Question 26

What is “swapped” in Virtual Memory?

Answer 26

Segments (variable size) and pages (fixed size)

Question 27

What is the Principle of Locality?

Answer 27

Objects that are near to each other in memory are often accessed around the same time, and objects that have been recently fetched may be needed again soon.

Question 28

What are the key features of the Principle of Locality?

Answer 28

Memory accesses are likely to be clustered. Instructions tend to be ordered or in small loops. Data is likely to be local. If a page has been swapped into memory to satisfy a memory request, subsequent accesses are likely to be nearby i.e. within the same page.

Question 29

What is a Thread?

Answer 29

A Thread is a basic unit of CPU utilization. It is a single sequential flow of execution of tasks of a process (or application that is being executed).

Question 30

What is Multithreading?

Answer 30

Multithreading is when multiple Threads are executing in a process at the same time.

Question 31

What is the number of processes in the Running state limited by?

Answer 31

The number of logical cores.