sem 1

Question 1

a computer system

Answer 1

1. user
2. application
3. Operating system
4. Hardware

software can be divided into 2 groups, applications and operating system.

applications need to be supported by the operating system.

applications will use a certain amount of memory, RAM, etc

Question 2

Describe the computer system in your own words.

Answer 2

applications help to solve the user needs, and they need to be supported by operating systems, where the operating system coordinates the resources of the application systems and controls the hardware.

Question 3

what are some examples of operating systems in the real world?

Answer 3

• windows
• iOS
• android
• Linux
• Unix

Question 4

what are the 3 objectives of operating system?

Answer 4

1. efficiency
2. convenience
3. ability to evolve

Question 5

why does operating system need to be efficient?

Answer 5

operating system need to be efficient as a Resource Manager.

OS needs to control the use of a computer’s resources. It is a software, and it needs to be executed by the processor. Thus, it needs to hand over control when necessary to other application programs, and it depends on the processor to let it regain control.

Thus, we can treat OS as a special software as compared to application programs.

Question 6

why does operating system need to be convenient?

Answer 6

operating system need to be convenient as a computer interface.

OS needs to handle the hardware for the users. OS also needs to make the job of an application programmer easier by providing services that the programmer can use.

Typically, OS provides services in the following areas:
- Program execution
- Access to I/O devices
- Controlled access to files
- System access
- Error detection and response
- Accounting

Question 7

why does operating system need to be able to evolve?

Answer 7

ease of evolution of an operating system.

A major OS will evolve due to hardware upgrades, new services and fixes.

Question 8

Multiprogramming vs Uniprogramming

Answer 8

Uniprogramming:
- less main memory needed as only one program sits in the main memory at one time
- less efficient use of the processor during periods of I/O operations

multiprogramming:
- main memory needs more space as multiple programs are sitting in main memory
- more efficient use of processor as another program can run while current program is waiting for an I/O operation.

Question 9

what are the 4 core functions of operating systems?

Answer 9

1. processes
2. memory management
3. Information Protection & Security
4. Scheduling and Resource Management

Question 10

what is virtualisation and what is a virtual machine?

Answer 10

The word virtualisation creating a virtual version of a device or resource, and that device or resource can be an operating system, server, or even network.

virtual machine:
virtual machine is a machine installed with virtualisation software that can run several OS. Host OS can run multiple VM (Virtual Machines)

A hypervisor sits between the hardware and the VM and manages the resources.

Question 11

Why do companies use Hypervisors?

Answer 11

1. consolidation: server can run multiple VM and increase efficiency by sharing its resources.
2. rapid development: a VM can be replaced in a very short time span as VM consists of files which are easy to copy.
3. ease of management: VM can be used in experimentation.

Question 12

Type 1 Hypervisor VS Type 2 Hypervisor

Answer 12

Type 1 Hyervisor sits between the hardware and the Guest OS.
- directly controls the hardware
- allows VM to be installed on it directly.
- usually has good performance.
- VM ESXI, Microsoft Hyper-V

Type 2 Hypervisor sits between the hardware and the Host OS.
- needs to go through the host OS to talk to hardware
- lesser performance compared to type 1 Hypervisor
- Oracle VM virtualbox