An operating system is system software that acts as an intermediary between computer users and hardware, managing memory through techniques like paging (dividing memory into fixed-size blocks called pages and frames) and virtual memory (creating an illusion of larger memory by temporarily swapping data between RAM and disk storage), while process management involves state transitions (new, ready, running, blocked, terminated) controlled by schedulers (long-term, short-term, and midterm) to optimize CPU utilization and system performance.
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Operating System - Free Paper Series Day 01追加:
Okay. A very good morning to all of you.
Is my audio clear?
Okay. So, thanks for joining in.
All right. Let's not waste our time and start with the lesson.
If there is anyone who need the YouTube link, you can drop me a WhatsApp message or click above.
Before that, can I know if you all tried the MCQs I sent you?
>> Yes or no?
>> Yes.
Okay, nice to see that.
So, operating system before that.
How many of you have studied the theory of this lesson?
Some are I think 2028 as well and there are 207 as well.
Raise your hands if you are studying the theory of this lesson.
Okay, looks like many are struggling with operating system.
So what is an operating system?
recordings as I mentioned I will provide only on valid reasons since it's a free Yeah, gas.
Okay. So, what is an operating system?
Is it an application software or a system software?
Let's see a short definition in the chat box quickly.
Yes, correct. So, it is a system software.
So, an operating system is a piece of software that acts as an intermediary between a computer user and the computer hardware.
Further we'll study some theories through the questions.
Hold on till I open it.
And I want everyone to reply to my messages. Be active, guys.
Can you all see the screen? I hope so.
Yes. So first we'll do more of questions. After that there are some FWC questions. At the end we will do fast paper MCQs as well.
So what is this MOA paper? I think most of all know you should be knowing it actually it's an IC exam conducted by the University of Mor students right they will conduct the examination every year so you can apply for it and go into the exam as a trial before the actual exam.
I hope you all know about that already.
I would recommend you to go and do that exam.
Okay, let's begin.
So, first one Okay. So, memory management technique in which system stores and retrieves data from secondary storage for user name is called. What is the answer? While I'm reading the question, I want the answers dropping in the chat box everyone.
quickly Nice.
Are you guys sleepy?
Is it so only few are replying?
or still on holiday mode entire questions we'll see until 2:00 let's see if we can complete everything if not I will skip and do only important questions I mean good questions okay guys quickly send me the answer I give you one minute I can see who is replying and not. So don't make me read your names as well.
Shall I select one person and ask the answer? I think that is better. Right?
If I don't get the answer in the chat box, I'm going to select one person say the answer.
Okay, I hope my audio is clear now.
Okay. Are you guys sure the answer is swapping or paging? What do you say?
Let's see how many gets it right.
Okay. If it is paging then what is swapping?
Right. So yes, many people fall for this trap and the answer is paging actually. So paging is a scheme that allows the operating system to retrieve data from a secondary storage like a hardware drive sorry hard drive in same size blocks called pages and place them into main memory which is the RAM. So this is a fundamental component of what virtual memory isn't it?
So I hope the ones who got it wrong is clear.
Okay. Mapping is another thing I ask swapping because many get confu confused between paging and swapping. So swapping is a memory management technique where an entire process is temporarily moved or you could call a call it as swapped out of the main memory and placed into secondary storage then brought back into memory later for execution.
All right. So that is clear, right?
So here it has they have mentioned stores and retrieves data right that suits best for what paging because swapping what does it mean? It means moving the entire process. So I hope that part was clear.
Okay, next one. Which of the following statement appropriately describe the Unix operating system?
What is it?
Is it a single usage single tasking operating system?
No. Right.
Is it a single again? It's not a single user. So that option is also out.
It is not a network operating system.
Then what is the answer? It is a multi-use. Yes. But is it a multitasking operating system or a single tasking operating system?
Yes, correct. It is a multitasking operating system.
So remember about this this word multi. Okay, good.
Okay. So what is an advantage of the virtual memory? First of all, what is virtual memory?
What is it?
Okay. So virtual memory it is a memory management technique that creates an illusion for users of a very large main memory. So it uses hardware and software to allow a computer to compensate for physical memory such as RAM stoages by temporarily transferring data from random access memory to disk storage.
So it temp. So what does it do? It temporarily access storage.
Okay. So the operating system has the ability to do another task while doing one task.
Is this an advantage of the virtual memory?
Yes or no?
No, right. That's not about the virtual memory.
But what does it describes?
This describes multitasking.
While virtual memory helps multi multitasking by letting more programs stay open, this is not the definition or direct advantage of virtual memory. Got it?
So it doesn't come under this the ability of using one CPU for many task. So this one refers to a CPU scheduling or you could say time sharing.
It is about how the processor manages its time across different jobs not about how memory is handled. So this is about process management. It doesn't come under management part sorry memory management part four both the ability of increasing the capacity of secondary storage.
This is wrong. Why? Because the virtual memory actually occupies space on your secondary storage to act as a swap file slightly decreasing the available space for your files.
So it doesn't increase the capacity of secondary storage.
In case you didn't understand any explanation, let me know.
So the prevention of fragmentation of hard disk in saving data files. So virtual memory does not do that right disk fragmentation is only the topic. So this is not related to it. But they're asking about here virtual memory. So the answer is the ability of keeping open the programs larger than the capacity of the main memory.
All right. I hope that was clear.
Now you know know that there are three types of allocations. What are those?
Can I know what are those?
There are three types and in the question they have mentioned one type contagious allocation in file management. What are the other two types in file management?
All right. Good. This Yes. So linked and index allocation.
Now over here they're talking about contigious allocation only, right?
Before I explain what is the answer, read it and quickly drop in the chat box. You have tried it, right? So what is the answer?
I want you all to try it first.
Contagiously allocated files cannot be used efficiently afterwards.
Okay, I got one correct answer.
How about others? Don't say silent, guys. Reactive.
Some of you asked study tips from me. I will say that at the end after we had discussed the questions.
All right.
Okay. Good.
This Okay, you're not active. So, I'm going to pick one person quickly. Drop me the answer the chat box. Let's see.
You haven't tried this, right?
I can't say. Let's pick one person.
Okay, don't leave because I'm checking on.
Okay. When I say I'm about to pick, I'm getting the answers.
No, I won't do that. Okay, good. Good.
See, you guys are active. Daisy to type or what?
All right. So, yes, the answer is fourth one like you guys said.
Contagious allocated files can be efficiently used after. Yes, since the file is stored in a contagious sequence of blocks, the disk head moves minimumly during read or write operations.
This results in what? Faster access time.
So that is correct.
It is efficient to find the space compatible with the size of the file in hard disk to save the file.
This is wrong. Why? Finding a large enough contagious block for a new file can be difficult. The system must search for a you know prehole which becomes less efficient as the disk fills up and becomes fragmented. So it's not efficient to file files in contiguous allocation.
Six. Sixth one, external fragmentation can occur due to contigious allocation.
Through as files are created and deleted over time, the free space becomes broken into small non-contigious blocks. Even if the total free space is enough for a new file, it cannot be used if it is not in a single contigious block.
So great that is an important topic.
Next we have a 2022 paper of the paper.
The data area that is used to store data in order to substitute the difference in operation speeds of various amount of data is called the what is it?
Yes, correct. The answer is buffer.
What is a buffer? It is a temporary storage area used to hold data while it is being transferred between two devices or processes that operate at different speed.
Example, between a fast CPU and a slower hard drive.
So I hope that was clear.
If there's any doubts you can ask which of the following is not an information common commonly found in the process control block of the operating system process number yes it is 10 BCB process scheduling state you have to know what state process is in is in program counter yes process state capacity of hard disk. So the PCB is a data structure used by the operating system to manage a specific process. It consists process specific data such as process state and process scheduling state such as if it is in ready state, waiting state or running state.
So they're asking which is not an information commonly found in PCB that is capacity of hard drive because it is a systemwide hardware specification not relevant to an individual process. I hope that was clear.
Okay.
So, next one I want the answer in chat box. The operating system uses various techniques for the space allocation of files. Among them, dash creates an index table at the time of file creation. See again they're asking about allocation types of allocation in file management.
Okay. Good. Yes. So it is index allocation.
So in index allocation all the pointers to various blocks of a file are brought together into one location called the index block. This block x has an index table allowing for direct access to any block of the file.
So remember that.
I hope it was clear.
Eighth one, the operating system maintains a page table for each process.
Moreover, to identify the entry of a virtual page, the virtual page number is used as the index. Which of the following is not inserted in the page table entries?
Not inserted in page table entries.
What is not inserted?
Okay, good. others.
Others quickly I'm waiting and the ones who are watching through YouTube if there's any issues any doubts you can ask me.
Okay.
What about this? Don't know the answer of this question about page table quickly guys. Yes or no? What is the answer?
Which of the following is not inserted in the page table entries?
Frame number it is valid and invalid bit.
Okay.
So frame number you know this is the core part of the entry mapping the virtual page to a physical frame.
Valid or invalid bit it indicates whether the page is currently in memory or not. Modified bit that is tracks if the page has been written to. Reference bit it tracks if the page has been accessed recently.
Page fault. This is an event or interrupt that occurs when a requested page is not in the page table. It is not the piece of data stored inside the table itself.
Was that part clear?
Why it is not inserted in the page table entries?
Yes. Okay. Good.
Okay. So, dash is the buffer that holds the inputs and outputs of another devices and it is a special area in memory or hard disk which is access accessible to input or output devices.
which is the most suitable word for the blank.
So it holds input and outputs of another devices.
It's an easy question.
Yes, correct. So it is spooling. Say it is.
What is spooling? It is a process in which data is temporary held in a buffer usually on the disk while waiting to be executed by a device or a program. So this is commonly used for what? For print jobs, right? It allows the computer to continue other task while the printer processes the data at it at its own speed.
Right? Was that clear?
Okay.
So dash is a system program that operates or controls a particular device attached to computer and also provides software interface to hardware devices.
Most doable word for the blank is what?
So it operates or controls a device that is attached to the computer and it also provides software interface to hardware devices. What is it? Another easy question to drop the answer in the chat box. I will be wait I'll give you one minute.
Even one minute is too much. Quickly guys, Lena Nora answer a Yes. So the answer is device driver.
So what is a device driver? It is a specialized software that acts as a translate with translator between the operating system and a piece of hardware like a printer, graphics card or mouse.
So it allows the operating system to communicate with the hardware without needing to know the specific details of how the hardware works.
Right.
So it provides software interface and it operates in controls a particular device as well.
Was that clear?
Okay.
Good.
So next is about the process state transition. You know there are seven states and in there are three types of scheduling that happens which is short-term scheduleuler, long-term schedule and midterm schedule.
Right?
So process is a program and execution.
Process changes through different states from its creation to termination. Which is the correct statement about process state transition?
That's correct. Cha a new process we only change its state to ready. Wrong. Why? Why?
Because a process often gets from new to ready.
It can also transition directly to other states or be aborted depending on the operating system design not only change to ready state. So that is wrong.
Right? So a process on running state can be switched to block state based on priority requirements.
That is also incorrect because a process usually transitions transits from running to blocked because it is waiting for an input output operation or an external event to occur. not priority based priority requirement typically causes a transition from running back to ready.
Okay, so that is also wrong.
So third one that is a correct answer.
Short-term scheduleuler assigns process from ready state to running state and it can be switched to terminated state after the end of its processing.
So short-term scheduleuler is also known as the dispatcher. It selects the process from ready state and assigns it to the CPU the running state. After completing its task, the process naturally moves to the terminated state.
So yes, the answer is correct.
Why is fourth wrong? Then we see that as well. long-term schedule which is the process from block state to swap out and block state.
Wrong because it's not the long-term scheduleuler that does that. It is the med middle term midterm scheduleuler which is responsible for swapping processes between main memory and secondary storage.
Yes. M. Okay.
Fifth. Why is it wrong? Process on the block state will be switched to running state after input output completion.
This is incorrect because a process in the block state cannot move directly back to running. It must first return to the ready state to be scheduled by the CPU once again.
So the answer is third one.
Was it clear?
Yes. Okay. Great.
Okay. Consider the following statements about operating system.
Programmer directly. So what are they asking? Which of the following are correct regarding generations of operating system?
Right?
So programmer directly interacts with the hardware and instructions are loaded directly into computer before the invention of operating system.
The answer is correct. Why? Because before operating system existed, programmers interacted directly with hardware and loaded instructions manually.
Option A is correct. B. In second generation operating system maximize the processor utilization and programs were recorded in magnetic tape. So that is through second generation. What is it known as? B system.
It used magnetic tape. Remember that as well. Second generation used magnetic tape to group to group jobs aiming to maximize process utilization.
So that is also correct.
In third generation operating systems were introduced to maximize the process idle time during input and output. This is incorrect because in third generation systems they introduced a multi-programming to minimize process idle time not maximize.
So this option is wrong. Right? In fourth generation operating systems minimize the respond time and maximize the user interaction during program execution.
Is it correct? Is it true or false?
through. Yes. In core generations systems example the personal computers and networks focus on minimizing response time and maximizing user interaction.
So the answer is A, B and D. Option number three. I hope that was clear about generation of computers operating system.
Which of the following cannot be considered as a function of operating system? Send me the answer in the chat box quickly.
Am I going too fast? You want me to slow down or is this okay, guys?
So the one watching through YouTube, sorry I missed your thing. I received your message later.
You can drop me WhatsApp message if there's any doubt.
Process stage seven explanation. Let it get you.
So I think it's the live chat is going a bit slow.
Okay. Hope hope everything was clear.
You can drop me a WhatsApp message if not.
Okay. Which of the following cannot be considered as a function of operating system? Keeping track of memory being currently being used by the process during multi program. So this is true.
Why? Because it does keep track of currently being used memory. Right?
creating processes and providing mechanisms for process intercommunication. Yes, it create process and provided creating files and folders and saving them in particular memory addresses that is also through providing user interface between hardware and the user that is the main function of operating system.
Keeping BIOS settings for the booting up procedure.
So this is the answer why because the virus it is a f store on a you know nonvalide chip. The operating system uses BIOS during booting it but it does not store or manage the BIOS settings themselves.
I hope that part was clear.
Okay, that's good. Right.
Hold on. This this Okay. So, next.
So, there's the same question. I didn't notice it. Sorry for that.
Okay. In multirogram operating system, which of the following is true?
It's an easy question, right?
answer guys quickly.
Lena answer Got four. Five others.
Think properly a answer. Answer.
Now what is the goal of quality programming system.
Still no one answered it correctly.
So the goal of a multirogramming system is to maximize CPU utilization by keeping the processor busy at all times.
So first one only one process can run at a time. We know that is false.
Third, only a single program is loaded into the memory that is also wrong, not a single program.
This describes uni programming.
In multirogramming, several programs are kept in main memory main memory simultaneously.
Input output devices are shared by all processes simultaneously.
Input output devices are typically dedicated to one process at a time to prevent data corruption. They are not used simultaneously by all processes.
So it is typically typically dedicated to one process at a time not used simultaneously.
That's why you all went wrong. Isn't it?
Each process runs to completion before another starts. This describes what batch processing multirogramming allows processes to be interrupted and received.
So the answer is two. CPU is switched between processes.
This is the core mechanism of multi-programmer. It ensures the CPU doesn't sit idle while a process waits for external events.
Was that clear? Many got that part wrong.
I think you all fell for this like simultaneously part option four.
Now once you got wrong was it all clear?
Do you want me to explain any part again?
Okay. Again I'll go one by one text options. Okay. So first one we know single only one process can run at a time that is not through multi programming. Okay.
CPU switched between processes. This is correct. Why? Because it ensures the CPU doesn't sit idle while a process waits for external events.
The fourth option, why is it wrong?
Because input output devices are typically dedicated to one process at a time, not simultaneously.
Right. How was it?
Okay, good. So be careful they this is how they trap you sometimes by these words the input are shared by all processes but not simultaneously right.
So these are the one of the ver question be careful.
Okay. Which of the following is so are correct?
It's already see the time. Thanks for saying we'll wait But until I Okay.
So, what is the answer for this 16th question? Which of the following is so are correct?
Yes, correct. The me the memory is divided into fixsized blocks called pages which are then mapped to physical memory using frames.
So yes this is in what in paging logical memory is divided into blocks called pages while physical memory RAM is divided into same size blocks called frames. So that is correct.
Virtual memory allows the execution of processes larger than the available physical memory. True virtual memory is a technique that gives the illusion of a very large main memory by swapping pieces of programs in and out of the physical RAM as needed. So that is also through it allows execution of processes larger than the available physical memory.
A data structure that contains information about a process is called the process control block through as I mentioned earlier PCB is a data structure used by the operating system to to store all the information needed to manage a specific process. So yes the answer is five ABC.
What is the major disadvantage of linked allocation? This is a question they often test.
What is it?
Guys, this It's our link allocation.
Good. I got two correct answers. Others Jamras Omar Elena.
I will read your names if I don't get answers.
If you guys reply only it will be a bit interactive. I don't want anyone to just say silent answer. Even if it is wrong, no problem.
I'm not going to judge you. Right.
Good. I'm seeing answers. Others.
Others. Answer.
Inefficient use of memory. This is incorrect. Why? While pointers take up a small amount of space within each block, link location is actually quite memory efficient because it utilizes every available disk block preventing what?
Preventing external fragmentation.
So that is not the answer since they asking the advant disadvantage slow access for large files due to sequent transfer.
So yes this is the major disadvantage of link allocation.
It is inefficient for direct access because it requires sequential transvers to find a specific block. The system must follow pointers through all preceding blocks. Right.
So that is the major disadvantage. Now high risk of external fragmentation.
This is false. Why? Because linked allocation completely eliminates external fragmentation.
because any free block on the disk can be linked to any file. I hope that was also clear. Some got that has the answer because linked allocation eliminates external fragmentation.
Any free block on the disk can be linked to any file. So it eliminates external fragmentation.
Right? Minimize wasted storage space.
This is not this is an advantage not a disadvantage.
Okay. Difficulty in file deletion. This is incorrect. Deleting a file in link allocation is straightforward.
So this is not a major disadvantage compared to the excess speed issues.
So the major there major disadvantage right. So this is slow access. I hope that was clear.
Yes. Yes.
clear. Okay, this is done.
Okay, good.
No three won't come because high risk of external fragmentation as I mentioned linked allocation it completely eliminates external fragmentation because any free block on the disk can be linked to any file.
So that is not the answer that is not a dis that is false. The answer is completely false.
Was it is it clear now?
Okay.
Next. Which of the following transitions occur when the process is preempt by the operating system scheduleuler?
Okay. So, I'm getting different answers.
And which of the following transitions occur when a process is preempted by the operating system scheduleuler?
So yes, the answer is one running to ready.
Okay, I'll explain this. Option two, running to waiting. Why it's wrong? The transition happens when a process voluntarily gives up the CPU because it needs to wait for an event such as in such as an input output operation or a signal.
In preeemption, the operating system forces the change. In this case, the process requests it. So that is wrong.
Third one ready to terminate.
A process cannot move directly from ready to terminated. It must been running state to execute its final ex instruction or to be eliminated by the operating system. I hope that was clear.
Waiting to ready. This occurs when the event uh when the event a process was waiting for like an input output task is completed.
So this is a key transition not a preemption.
The process is becoming eligible to run again not being kicked off the CPU.
Now preemption when does it happen? It happens when the CPU scheduleuler interrupts a process to give the CPU to another process forcing the current one back to back into the ready Q to wait for its next turn. Was that clear?
So preeemption happens when the CPU scheduleuler interrupts a process to give the process to another process.
So it forces the current one back into the ready Q to wait. So it's running to ready. Right.
Fifth one won't come because this this transition ready to suspend is often known as what? Swapping. It is handled by the memory manager not the CPUuler.
They asking about the CPU schedule.
Right? So this one also won't come.
Was it clear this as for which one you meant?
and ready to run. Ready to terminate or waiting to ready to ready.
So that is the answer.
Why? Because in pre when preeission happens when the CPU schedule interrupts a process to give the CPU to another process for the current one current process back into the ready queue to wait for its next turn.
So it moves the current process in back into ready. So running to ready it means say when process is preempted preempted was it clear now?
Okay anything wasn't clear let me know.
All right. So last year paper.
So when you're doing this paper, you'll notice that they are having the same pattern as well.
And I would recommend you guys to do this exam or examination this year. I don't know. They haven't released the date yet, right?
do it so then you can test your ICT knowledge should be like you facing an final examination.
Okay. In the operating system dash helps increase file retrieval speed by consolidating fragmented files on the hard disk.
Which of the following is most suitable for filling the blank?
It's an easy one.
Think and answer again sometime.
Okay, I got one answer correct.
This other Khadijah Omar reply reply Jamas Okay, good. I'm getting answers. Others others just at least if you're not sure also say no problem give a guess.
So what helps increase file retrieval speed by consolidating fragmented files or not this what the helps it at least give a guess if you don't know try it even if it's wrong no problem don't Interesting.
Okay.
All right. So yes, many are confused. No problem.
Fragmentation.
Fragmentation is the problem itself.
What is fragmentation? Files are scattered in in uncontagious pieces across the disk which actually so slows down the retrieval speed.
So they asking away helps increase file retail speed. So that is wrong. That is the problem. Actually if you have printed this MCQs you can write next to it menturing it has the problem that it is the problem itself right I would say it's better to get a print out if operating system is a weak lesson for you. Get the print out and get the recording for me and do it again.
First take a print out. Do the answer it yourself. Get the recording and correct it.
Okay.
Second, a disk partition.
So this involves what? Dividing a hard drive into separate logical sections. It helps with organization but does not reorganize the data within those sections to speed up individual file access. It divides but it does not help with speeding up. So that is also wrong.
Defragmentation.
Yes. So def fragmentation is the answer.
Okay.
The why not task manager this you know what it it does it is a tool which monitors active processes and system performance but it does not reorganize files on the disk. So that is also incorrect. File manager also is incorrect. This is the user interface used to browse and organize files of folders.
So the answer is three. Def fragmentation. I hope you all know what is def fragmentation.
Yes. All clear. This one.
Yes. Yes. Good.
So you know what is the fragmentation right? It is a maintenance process that reorganizes the data stored on a hard drive to improve system performance.
So over time as files are created, deleted and modified, they become fragmented, meaning pieces of a single file ended up scattered across different physical locations.
Okay.
All right. Next one. Consider the following paragraph about what about virtual memories function in an operating system.
So dash may require more memory than dash when executed.
between RAM and dash. Virtual memory works by temporary swapping parts of program data and code between a dedicated area of the hard disk. This process is known as dash. Ensures that the active parts of a program are catched on the RAM while the useless parts are stored on the hard disk. Now some of you all might be confused what is happening this way. First option dash may require more memory than what when executing.
What gets executed?
Program. So program may require more memory than physical memory when you're executing.
Isn't it?
Then between RAM and page file, virtual memory works by temporarily swapping parts of program data and code between a dedicated area of the hard disk between RAM and what between RAM and page file.
So last one you know this process is known as what paging.
Now in the first option they are given page file which is wrong because program only requires more memory than physical memory. So first option is wrong. Second one paging may require more memory than physical memory. That is wrong because the process name is only known as paging. So where is paging? We are sure right.
So that is also wrong.
So the answer is yes. Third one program.
We'll go to the fourth option. Fourth option. Physical memory may require more memory than program. That is wrong because physical memory cannot require more memory than a program. Rather, it is the program that often requires more space than the available physical memory. Which is why virtual memory is needed.
I hope that was correct on why physical memory doesn't require more.
So that is also wrong and fifth is also wrong because last option they mentioned physical memory and page file process is only known as paging.
Was that part clear? Option two is wrong because paging is the name of the process not the entity requiring memory.
Was it clear? You might get confused when you first what you if you're getting confused for questions like this. First eliminate the most incorrect answer.
If you have doubts between answer first eliminate the wrong ones then you will somehow get the correct answer. Okay.
I hope that was clear.
All right. So which of the following is an advantage of virtual memory?
which is the advantage of virtual memory guys.
I just mentioned it right Okay, good. Others good.
So you see this paging virtual memory has been repeatly tested. So focus on that topic. Well yes correct correct.
No. Okay, Lena.
Yes, got it now.
Okay. Yes. So, which of the following is an advantage of virtual memory?
Eliminates the need for physical memory.
Wrong. Because virtual memory requires physical memory to function. It is a memory management technique that uses secondary storage to supplement RAM not replace it. So that is no.
Yes, the answer is second one. It allows for executing processes that exceeds the size of physical memory. So the primary purpose of virtual memory is this. It uses a technique what called paging. It swaps data between RAM and the hard hard drive.
Okay, I hope that was clear. So why is option three wrong? A accelerates execution time of the CPU. It's wrong.
Accessing data from secondary storage is significantly slower than accessing RAM.
Right? That is also wrong. It reduces memory requirement of cage memory.
So virtual memory and c memory serves different purposes.
That's also wrong and reduces memory requirement of main memory.
Virtual memory does not require the physical RAM required for the system. It allows system to run larger programs than the RAM would permit.
So it does not reduces memory requirement of main memory.
All right. So we had started.
So we done with the Mora questions for 2021 to 2025.
Shall we move on to past papers directly?
Let's see. This is an FWC questions.
Shall we do past papers and come back to FWC papers? I think that is better, right?
Okay, we will do passwords.
I think that is better than others from 2016 onwards.
Right. Try this question.
Quick, quick, guys. It's an easy one.
Okay, great.
So in an operating system suspending the currently executing process and then resuming or starting another process is termed as suspending the currently executing process. What does it context switching not interrupting context switching?
So what is context switching? It is the mechanism of storing the current state of a process so that it can be paused and resumed later. This allows multiple processes to share a single CPU efficiently.
I hope that was clear.
So first one is wrong because paging it is a memory management scheme while here we are talking about what process management.
So that is wrong. Swapping it is moving a process between main memory and secondary storage. It does not saves the current state. Interrupting it is a signal to the processor that temporarily holds. It just holds the current task.
So that is also wrong.
Blocking it is a state where a process waits for an input output to occur.
All right. So the answer is context switching. I hope it was clear. Now in modern computing operating systems, sorry, in modern operating systems, the dash scheduleuler determines the transition of processes from the new state to the ready state. Which of the following is the correct term to fill in the blank in the above statement?
with schedule it which determines the transition of processes from the new state to the ready state guys which schedule does it shortterm with term longterm Say this is a 10 year ago past paper question. See how they have been tested.
Answer don't know.
So schedule a part many people get confused.
Okay. So midterm what does it do? It handles process that needs to be swept out of memory temporary.
swept out early does swapping swapping.
So that is wrong. Did they say over here swept out? No. Right. But they say from new to ready state.
So the answer is long-term scheduleuler which is also known as job scheduleuler.
Remember the other name as well. It controls the degree of multi-programming by selecting which process from the new admitted into the ready Q in main memory. So this is what the long-term scheduleuler does. It selects which process from the new admitted into the ready queue in main memory.
That's nothing very longterm, very shortterm and shortterm scheduleuler.
Okay. So short-term schedule is also known as the CPU scheduleuler. So another name for long-term was what? Job scheduleuler.
For short-term it is known as CPUuler.
It selects which process from ready Q should be executed next. Not from new to ready but from ready Q only it does.
Okay. So the answer is option two. I hope that was also clear.
Next 2017 question.
The execution of series of non-interactive jobs on a okay this is not an operating system but try it.
This is this can also come under this one chap unit one as well.
So the execution of a series of non-interactive jobs on a PC with relative to the user is known as what is the answer non-interactive jobs on a PC.
Okay, we'll go with the first option.
Okay, multitasking. Multitasking, what does it mean? It refers to a single user running multiple applications. Did they say over here about single users or anything?
They saying what series of non-interactive jobs.
So not multi-user processing it is a use of two or more CPUs within a single computer system not related multiprocessing multiprocessing I just said okay sorry it is a use of two or more CPUs within a single computer system multi-user you know multiple users are using it then online processing it requires is continuous connection and user interaction.
But in batch processing, it involves collecting programs and datas into batches and running them without user intervention.
So the answer is four. Batch processing.
Was that clear? Not online, not multiprocess.
Was that part clear?
Series of non-interactive jobs.
Multiprocessor.
It involves collecting programs and data into batches and running them without user intervention.
Okay, I hope that was clear.
So another 78 question. Which of the following statement is correct?
Application software load applications into main memory. It is false because the operating system is a type of system software not application software is responsible for loading applications into main memory.
The application does not what does it system software that's the program stored in Rome are known as system software.
So programs stored in read only memory what are they known as?
What is a program stored in ROM? Known as not system software. What is it guys?
Think think firmware right remember forgot basics programs stored in read only memory are known as firmware bios and Okay, I hope that was clear.
So option three, system software supports data communication between peripheral devices.
Is this true or false?
True. Right? Because system software such as device drivers it facilitates the communication between the computers hardware and verified devices example scanner printers.
So that is correct.
Utility software is generally stored in RAM.
That is wrong because utility software means like antivirus or dis clean is typ typically stored in the hard drive not in.
And fifth one utility software is incorporated in washing machines. So washing machines they use embedded embedded software known as like firmware not general utility software to control their functions should be embedded.
Okay. I hope that was clear.
Okay, next. Try this out.
Guys, are you all sleepy, bored, or what?
You want know the answer?
First paper seems a bit tough. Is that so?
Need a break.
Who needs a break? Raise your hands.
Let's see. I'll go with majority.
So doesn't what should I do?
Should I give a break or no?
4 minute break.
How about this?
Need a break.
Okay. Okay. 5 minute break is enough, right? Don't leave. Don't leave the meeting because I know if you leave, you will take 50 minutes to join back. Stay in the meeting.
10 minutes is too much. We have to do until I 2024.
See which question number is this? 44.
Okay. 8 minutes. Very nice.
Okay. 115. Don't leave. Shut up. 115.
You should come back.
Just keep the meeting on and come back.
1:15.
Okay. Three says yes. So, okay. Take a break.
Others. If there's any doubt, any question, you can let me know. Those who don't want a break, try the boss questions.
And once who are watching through YouTube any doubts you can ask me now.
Okay, enough of this.
Okay. Are you all there? Raise your hands. Let's see.
And there's this So many are dropping on some messages now asking for recordings.
Okay. So, shall we start? Okay. Try this 44th question. This doesn't 18 question.
Quickly try and drop me the answer.
So, which of the following is true of correct?
Disk defragmentation makes files that are fragmented in a disk contagious.
Is it true or false?
True or false? Guys, are you all there was slept in the break?
I want Okay, everyone raise your hands once again. Lina, Kar Guys, answer. Answer.
Okay. So, disk def fragmentation makes files that are fragmented in a dis contagious.
Yes, it is correct. Defragmentation, what does it do? It reorganizes data so that the file parts are stored in contigious sectors improving read or write speed. So that is through swapping is a memory management technique where the main memory contains which were not recently used are copied to disk to make the memory available for other processes. Yes. So swapping what does it do? It moves processes or memory pages between RAM and secondary storage means the disk to optimize memory usage.
Right?
So that is also correct. Option B is also correct. Okay, a file allocation table is a table that an operating system maintains which provides a map of the clusters that the file has been stored in. This is also correct. F means file file allocation table is a leg it's a file system architecture that uses a table to track the physical locations means the clusters of file on a disk.
So that is also true.
The answer is five or A B C.
Was that part clear?
here guys. Was it clear? Was that clear?
Please say in the chat box. Yes. So, okay.
Okay.
40. Through which of the following will a device controller that controls a device deal with the operating system?
An easy one. Which controls the operating system?
The device driver. What is a device driver? A type of software that acts as an interface between operating system and hardware device controller. It translates operating system commands into instructions that the hardware can understand.
So that's an easy one.
Which of the following is a hardware device that maps virtual address to physical address?
Which does that answer? Answer. It's the easiest question.
See 2019 one quickly guys.
So it is memory management. We all know that it is the hardware that maps virtual address to physical address.
Okay. Now, now on a single processor computer, a user starts a spreadsheet application and creates a new spreadsheet. To get some information required for the spreadsheet, he opens a large database using his database management system.
After completing his spreadsheet, he saves it.
Okay. Which of the following operating system feature has or have been used by the above user? I just thought this a while ago.
So as context switching it saves the current state file management also it happens because it is storing in the database management virtual memory also.
So the answer is all A B and C.
Was that clear?
Okay, I hope that was also clear, right?
So consider the process transition diagram in the figure. If the transitions shown are as follows, then what are the states indicated by the labels A, B, and C respectively?
Can someone try this question?
So first one what happening? What is happening is process blocks for input output.
So what do you think A is from A to B?
What is happening? The process blocks for input output.
Okay, read it. Try and let me know the answer.
So, okay. If it is wrong also, just try.
We only have few days left. If you don't do past papers now, no use.
I would say to do 2011 actually Lena Jamas I try zero.
Okay. So what is happening in one the process requires an input output operation right.
And in two from A to C what is happening is schedule picks another process.
So A is ready to running.
A to C is ready to lock. Wait, wait, wait.
Sorry. Sorry. Yes, the question is ready to blocked. Option four. Actually A is running, B is blocked, C is ready.
So what happened? Running to blocked.
What happening? What is happening is the process requires an input output operation and cannot continue. Right?
And in running to ready means A to C, the scheduleuler frames the process, right?
In third one means C to A which is ready to running. The scheduleuler selects the process to execute next.
Fourth B2C what is happening? Block to ready the input output event the process was waiting for has finished.
So the answer is running blocked and ready.
I hope that was clear. Now which of the following is not an information stored in PCB of the operating system?
So program count is there. Memory identification is there. Identification number process state is also there. What else?
Memory management information for the process. Yes, that is also there. What is not there? Three disk slots.
Simple. We did a similar question earlier, right? The operating system is another program that runs on the computer that has some special responsibilities.
Memory management, file management and input output management are some of the responsibilities which is another important response. Okay, which is another important responsibility of the operating system. They asking apart from the ones they have mentioned which is it.
It has respons. What is that? Memory management, file management, input, output. Is there something called backup management? No.
C management? No. Compile management?
No. Process management? Yes. You all know the types of management.
So that's an simple question. There nothing simple. Clock management. Sorry, system block management.
So the answer is process management.
Okay. When the number of processes started by a user on a single processed computer increases, what happens to the response time of each process as perceived by the user and the memory management related work of the operating system respectively.
So what happens when the number of processes started by a computer increases? What happens to the respond time?
Option one, both the respond time and the memory management work related increase. Yes, both increases. Respond time decreases. No, the respondent doesn't decrease, it increases in fact.
So that is wrong. Respond time increases while the memory management work. Memory management work also increases.
Since they are starting another one both the respond time and memory management related work decrease that is also false. There is no change in either of them that is also false.
The answer is both of increases.
Was that part clear?
So what is respond time? You all know in a single processor system CPU is CPU time is shared right. As the number of processes increase each process receives less frequent CPU cycles causing this response time to increase. Okay. Okay.
Memory management. With more processes, the operating system must work harder to manage address spaces, page tables, and potential swapping. Therefore, memory management work also increases. So, both increases. I hope that was clear.
Next one. Which of the following is not a responsibility of the operating system?
Allocating physical memory to processes is that the responsibility of the operating system? Yes. But what are they asking? Not a responsibility.
So that doesn't count.
Deciding which process to run. Yes, it is a responsibility.
Keeping track of the usage of compiled program file on the hard drive. hard disk.
So that is not the responsibility of an sorry that is not a responsibility of the operating system. The operating system manages files and disk drives but it doesn't track the specific internal usage or execution path of a compiled program.
So that is the answer because it is not a responsibility of tracking it. Keeping track of which parts of physical memory are in use and which are free. That's what it does, right?
And swiping processes that also operating system does. See it's a 2020 pass paper not that hard, right?
In a computer the size of a user program could exceed the size of physical memory. Also only the demanded area of programs are kept in physical memory.
Double is due to which of the following?
The same thing they are testing in different different words. Look.
So now if this year they giving you the options of the use of country's US file location, next year they might put the option on like a question.
That's how they usually do. The pattern doesn't change.
What is answer chamom?
Answer answer question number 53.
the use of what are they describing above?
Simple paging, right? Isn't it? The use of page frames and page tables. So, they're describing the scenario of virtual memory and paging.
Five. Yes, correct. That is the answer.
So others we have studied earlier. I'm going to explain right. Which of the following is a good example for batch processing?
This is a unit one related one but processing notice payroll.
So payroll you know they collect everything in batches and then executed it in batches. Right. Right.
No.
Okay. Sorry.
Okay.
So Amara loss into a single processor computer and starts a program to work on his presentation. He opens a web browser to get some information as well. They ask a similar question like this earlier as well. Isn't it?
Now they are asking what is happening over here the state.
So a what is happening in a ready to running ami saving it presentation on the hard disk. So that is what ready to running right.
Sorry.
Okay. Now, am I saving it presentation on the hard disk that is happening to running to ready? I said the opposite way. Sorry.
So, am saving it presentation on the hard disk. What is happening running? It is going from running to ready state, right? When you save it right now from ready to running, what is happening? The finishing of saving the presentation on the hard disk.
So option A it is fourth one whereas B it is one. The reason of why the state is changing in C. What is happening?
Operating system suspending the presentation process to let the web browser process to run on the processor.
So it's get from block to ready state.
because it is letting the web browser processor to run. So from block to ready it is going right now from running to block what is happening the operating system scheduling the presentation process to run on the process that I hope that was clear.
Did you get this part or want me to explain in a in depth?
Why is this happening? Because it's a single processing computer, right?
Was it clear guys or do you want me to explain in depth?
Please say yes or no. Was it clear?
Clear.
Everyone not clear.
Okay.
So in a what is happening? It's going from ready to running. Right.
Okay, just hold on this question.
Is there a error there something? Let me just check out.
Okay, just come back. This is at the end. I think there is something.
Okay, we do this next.
Okay. A page table. What is a page table?
Is it a computer hardware unit through which all the memory reference pass?
False, right? A data structure that keeps information about the pages that are in process cages. No, that is also part a hardware component in memory that facilitates page movement. No, it's not a hardware component.
So, what is a page table? It is a data structure maintained by the operating system that stores the mapping between virtual address and physical address. So the answer is fourth one All right.
Okay. So, next we have is about the file allocation table. But this there's a calculation part to do.
Okay, this one I thought to do with paper to you know the structured part.
So I will leave this and the answer is 103 actually. So it starts with you map it this way.
So it's ended what 103 from minus one is the starting from that what is the next number next to it 101 101 go find it 101 next to it is 100 next to 100 it is 103 after that there's no any number so that is the directory entry for the my program file and that is space is 12 KB.
How do you find 12 KB? Because it alloc file occupies three blocks, right? 103 101 100.
The given block size is over here. 4K.
So three blocks into 4 KB. How much is it?
3 works into 4 KB is 12 K. So that's the answer. We did it in that way.
Okay.
Yeah.
Which of the following requires real time processing? This is not about predict system. I will skip that. Okay.
A program execution in a computer is called a process. Such a process transits between several states during its lifetime. Which of the following correct key represents a possible straight transaction sequence of a process?
Which of the following is correct?
Nice.
think think purple and I give some time.
So the correct answer is one from new to ready, ready to running, from running to waiting.
So in new what is happening? The process is being created in ready the process is loaded into memory and is waiting for the CPU to pick it.
Right? In running the CPU is currently executing the process instructions.
Invading or block we can say as the process cannot continue until a specific event occurs like a like waiting for a user input.
Right? So under ready it goes to ready again once the input output event is finished the process doesn't go straight back to the CPU. It must go back to the ready queue to wait for its turn.
Then it comes back again to running. The CPU picks it again to finish execution.
At last the process finishes its execution. Right?
So in option three and four a process cannot go from new to directly running.
So that's wrong.
In option two, a process cannot go from waiting directly to running.
So that's why those are wrong.
Okay. Which of the following is not a task of computer operating system?
Try this question.
What is the answer? Which of the following is not a task of computer operating system?
Okay. Selecting memory frame for a page of a process.
So this is a task of what? Memory management.
Maintaining a list of prememory frames that is also memory management. The operating system must track which parts of memory are free.
Okay.
Maintaining a PH table that is also memory management. So it is a task monitoring the usage of binary files on a hard disk.
Okay. While the operating system manages the file system, it does not monitor the usage of specific binary files. So that is the answer. It is not a task of operating system.
Monetary file usage is usually the job of application software. Right?
So there's another one as I said earlier how to do this.
Just look at the flow I'm going in.
So it ends at 203 as I said.
How many bucks are being used?
guys. Answer. Answer. Try it. I already did one earlier.
So four blocks are being used and the block size of disk is 4 KB. So 4 into 4 is 16. The answer is 16 KB. And why 2003? Because it ends at that right four. Yes, correct. I'm good.
Okay, since we did a similar question like this, I'll skip it. Which of the following causes CPU to execute a different set of instructions?
The answer is five. You know have I explained everything earlier again a similar question this one PCB I already thought right.
Now Amara switches on a multi-user computer. Earlier it was a single processing computer, isn't it?
Yeah, it is a multi-user computer.
So after it has booted, Sama logs on to the computer from a terminal and starts a web browser. After some time, Sama starts a text editor also to work on a Python program. Then Rani also logs in to the computer from another terminal and starts a web browser. Which of the following are pos possible execution sequence on the processor of this computer?
So I'll just read to say the answer and explain it is one because you know BIOS is starting it and after that followed by the operating system take control right then it opens up some web browser process after then the operating system it what it does context switching it saves the current process and opens up SA's text editor process After that it includes Rani's web browser process.
This is wrong because bias does bias always starts first right. So those options are wrong.
In this option operating system context switching should happen.
Okay. I hope that was clear.
Now each block of a disk is 512 bytes.
When a file size of,959 bytes is stored on the disk, how many bytes allocated to the file would be wasted?
So how do you do is,59 divide by 512 you won't get a point number full decimal number instead you have to round it off. So when you round it off you'll get it as four blocks.
So 4 into 512 bytes the answer would be 248 bytes. 248 bytes subtract it from okay 248 sorry 248 bytes subtract it from 1959 bytes we'll get the answer as 89 was that part clear guys we have done It's 2:00 as well. This PCB question we did already earlier. I mean I already thought all about PCB 64 also the answer is one.
Was it all clear guys?
Early I didn't do the FWC questions.
Okay. Was everything clear?
Okay. Was everything clear? Jamas Lina, it's 2:00.
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