Chapter 2.7 (Functions of an operating system)

Question 1

What is an operating system?

Answer 1

An operating system is a program or set of programs that manages the operations of the computer for the user

Question 2

What are the functions of an OS?

Answer 2

• Provides user interface
• Interrupt service routines
• Processor scheduling
• Memory management
• Peripheral management

Question 3

What are two examples of memory management?

Answer 3

Virtual memory and Paging and Segmentation

Question 4

What is the difference between paging and segmentation?

Answer 4

Paging - Data is physically divided into fixed sized pages to store data non-contiguously

Segmentation - Data is logically divided into different sized segments to be stored non-contiguously

Question 5

How is Virtual memory used?

Answer 5

The OS may swap pages of temporarily inactive jobs to make room for the process being called

Question 6

What is an interrupt?

Answer 6

An interrupt is a signal from a software program asking for the CPU’s time

Question 7

When the OS Receives a interrupt what happens?

Answer 7

Priority is checked

• if higher priority, all actions are stored in a stack and suspended and then an interrupt service routine is loaded
• if lower priority, processes are handled like normal

Question 8

What types of processor scheduling algorithms are there?

Answer 8

• Round robin
• First come first served
• Shortest remaining time
• Shortest job first
• Multi-level feedback queues