Operating System Intro (PPT 1)

Question 1

What is an Operating System?

Answer 1

It is a complex program which is in charge of the computer.

Question 2

What are the three main purposes of the OS?

Answer 2

• Provide an extended machine interface (for the programmer)
• Provide efficient, safe management of computing resources
• Provide a user interface for user interaction

Question 3

What would a programmer have to know if there was no operating system?

Answer 3

• The ins and outs of hardware, in detail

- Be able to access and program the hardware

Question 4

What would every program need to contain if there was no operating system?

Answer 4

• Would have to contain code to do the same thing so lots of duplication
• Would probably do something wrong and clash with another program

Question 5

What does the OS provide to programs?

Answer 5

• A simpler, more powerful interface

- Higher level services

Question 6

How are OS Services accessed?

Answer 6

OS Services are only accessed by system calls. The user and programs should never have to directly interact with the hardware

Question 7

What does a program see the OS as?

Answer 7

It sees it as a set of system calls, called the Application Programming Interface (API)

Question 8

What is the Kernel?

Answer 8

This is the main OS program, it contains code for most of the services. Always in primary memory

Question 9

What are Device Drivers?

Answer 9

These are programs which provide a simple, consistent interface to Input/Output devices. They are typically part of the kernel.

Question 10

What is a Program?

Answer 10

A static file of machine code on a disk. Dead code

Question 11

What is a Process?

Answer 11

A program in execution. “Living” code. The collection of resources and OS data structures owned by a program while it is running

Question 12

What are some examples of OS functions?

Answer 12

• Open
• Read
• Print
• Close

Question 13

What is the process of adding a new device on a old OS?

Answer 13

• Get the device driver software
• Recompile the kernel with the new device included
• Re-boot the machine so the new kernel and driver will be used.

Question 14

What is Micro-Kernel Approach?

Answer 14

This is a newer method for kernel structure. The kernel contains the minimum functions and the rest is provided by user level processes

Question 15

What is contained within the Micro kernel?

Answer 15

• Memory management
• Basic CPU management
• Inter process communication
• I/O support

Question 16

What characteristics does a Micro Kernel have?

Answer 16

• Easy to replace server
• Can have multiple personalities
• Makes use of message passing
• Easier to write and port the operating system
• Design is perfect for distributed systems.

Question 17

What to Operating Systems tend to be?

Answer 17

• Micro Kernel based
• Support multiple personalities
• Give much greater support for networks

Question 18

How is Microsoft Windows structured?

Answer 18

-Single user, multi tasking, interactive applications
-Supports threads
-Symmetric Multi-processing (supports multi-core or multi-processors)
-use of object oriented concepts
-Structure for user mode and kernel mode:
Hardware abstraction level for different hardware

Kernel

System Functions and API

Special System support, server processes, OS personalities