Chapter 1 Basic Concepts of an operating system Flashcards
(51 cards)
Which steps are performed by the computer when we do booting (When we press power button)
(i). It runs various tests to make sure everything is working correctly.
(ii). It checks for new hardware.
(iii). It then starts up the operating system.
Using what program does computer actually start the operating system
Bootstrap Loader
Where does the bootstrap loader reside in our computer and how is it exectued
Bootstrap Loader is a program that resides in the computer ROM, EPROM or in non-volatile memory that automatically .executed by the processor when the computer is turned on.
What is non volatile memory
Non-volatile memory retains data when power is removed. Examples include ROM, PROM, EPROM, EEPROM, and flash.
What is EPROM
EPROM (Erasable Programmable Read-Only Memory) is a type of non-volatile memory that can be programmed electrically
Bootstrap Loader is also known as
bootstrapping or boot loader.
What happens internally when we open a .c file through turbo editor
When we are giving an “open” command from the Turbo editor to open a “.c” program file, at the time turbo editor, an application program will send a request to an operating system for the file. Now operating system will come into the picture. Operating system will interact with the computer hardware, it means here hard disk, because file is stored on hard disk, Then file will be transferred from hard disk to main memory. That means “.c” program file which was requested before is now available and open to process further
Explain entire bootstrapping procedure
- Operator powers on
- CPU executes bootstrap loader from EPROM
- Reads the boot sector of hard disk
- Copies operating system from boot sector to main memory
Explain all things involved for user to communicate to hardware
Users ↔ Application ↔ Operating System ↔ Hardware System
How many managers does OS have and which are they ?
Mostly 5 but 4 in some old ones where they don’t have networking capabilities
1. Memory Manager
2. Processor Manager
3. Device Manager
4. File Manager
5. Network Manager
What are the tasks that all the managers of the OS have to perform
- Supervise the status of the resources continuously. It means each manager has to check the resources are free or busy. Here resources can be memory, CPU, any file or any device.
- Design the rules which determine who gets what, when and how much. Each manager will apply the policy which will decide who will get
access to which resource, when and for how much duration access is allowed. - Allocate the resource Each manager will allocate the resource when it is available.
- Deallocate the resource. When the usage of a resource is completed or maximum time to use the resource has elapsed, each manager will just take the resource back from whom it was given. So after the usage resource will be
deallocated by the manager.
Who is responsible to monitor the allocations and deallocations of main memory
Memory Manager
What will will memory manager do when a request comes in for memory
- Check if there is enough space in main memory (RAM) to full fill the request
- If Yes, then allocate
- If No, then reject the request that is why sometimes we get error like “Not Enough Memory!”
How dose memory manager handle multiuser environment
In multiuser environment memory manager keeps a table which indicates which user is using which portion of the memory. So when the user task is completed, the memory which is allocated to him will be deallocated.
Memory manager will also take care that not a single job access the portion of the main memory where operating system is loaded.
What is the job of processor manager
Processor manager takes the decision that how Central Processing Unit (CPU) should be allocated.
Processor Manager has what 2 schedulers and what are their jobs
- Job scheduler
is the high-level portion of the processor manager, which is responsible for accepting or rejecting the jobs. - Processor scheduler
is the low-level portion of the processor
manager, which is responsible for deciding which process will get the processor and for how much duration.
Device manager allocates various devices in efficient way by using various _________
scheduling policies
Which manager is responsible for handling compilers and assemblers in our computer
File Manager
Explain how all the managers will work together when we execute Dos command DIR
(DOS, or Disk Operating System, refers to a family of operating systems that provide a command-line interface for interacting with a computer.)
- User will press the keys D, I, R on keyboard. When these keys are being pressed at that time the electrical signals will be generated and from that device manager form the command “DIR” and send it to the processor manager.
- The processor manager validates it and with the help of the device manager user will be able to see it on the screen.
- Now processor manager will check for the file associated with the command, whether it is in the main memory or in the hard disk.
- If it is in the main memory, then it will be executed and processor manager sends output to the device manager, with the help of it the output will be visible on the monitor.
- If the file is not in main memory, then file manager will calculate its exact location on hard disk and sends this information to device manager.
- Now device manager will retrieve the file from the hard disk and gives it to the memory manager. Memory manager will calculate the exact location for the file in memory and will store the file at that location.
- Once the file is located then it will be executed by processor manager and then with the help of the device manager, output will be displayed on the screen.
What are some of the different types of OS
Batch OS
Distributed OS
Multitasking OS
Network OS
Real-Time OS
Mobile OS
Explain Batch OS
This type of operating system does not interact with the computer directly. There is an operator which takes similar jobs having the same requirements and groups them into batches. It is the responsibility of the operator to sort jobs with similar needs. Batch Operating System is designed to manage and execute a large number of jobs efficiently by processing them in groups.
Advantages of Batch OS
- Multiple users can share the batch systems.
- The idle time for the batch system is very little.
- It is easy to manage large work repeatedly in batch systems.
Disadvantages of Batch OS
- CPU is not used efficiently. When the current process is doing IO, the CPU is free and could be utilized by other processes waiting.
- The other jobs will have to wait for an unknown time if any job fails.
- In a batch operating system, average response time increases as all processes are processed one by one.
Examples of Batch OS
Payroll System, Bank Statements
