1) In terms of DMA (Direct Memory Access), which of the following statements is
ID: 3754346 • Letter: 1
Question
1) In terms of DMA (Direct Memory Access), which of the following statements is TRUE? (Chapter 1)
A. it is implemented only in real-time operating systems
B. it can only be used to access databases
C. a user’s program can use it to access the main memory
D. it controls the flow of data between memory and some controller without constant CPU intervention.
2) The program counter is controlled and updated by (Chapter 1)
A. superusers
B. operating systems
C. users’ programs
D. web browsers
3) Which of the following statements is NOT true? (Chapter 2)
A. Processes can share their address space.
B. Processes support the ability to have concurrent operation even when there is only one CPU available.
C. Processes can be created and terminated dynamically.
D. Processes can communicate with one another using interprocess communication primitives.
4) The CPU scheduling algorithms are used to (Chapter 2)
A. identify which process/thread is currently using the CPU
B. check how much time has been used by the current process/thread
C. determine which process/thread to run next
D. decide whether or not the current process/thread should be terminated
5) Consider a physical address with a page frame size of 8KB. How many bits must be used to represent the page-frame offset of the physical address? (Chapter 3)
A. 8
B. 10
C. 12
D. 14
E. Your answer: _________
6) To make paging systems work well, we have to consider the following issues except? (Chapter 3)
A. naming the processes
B. selecting page size
C. choosing page replacement algorithm
D. determining the working set
7) In operating systems, “busy waiting” is defined as (Chapter 2)
A. the situation where two or more processes are reading or writing some shared data and the final result depends on who runs precisely when.
B. the part of a program where the shared memory is accessed.
C. the situation where a variable is continuously tested until some value appears.
D. the situation where if one process is using a shared variable or file, the other processes will be excluded from doing the same thing.
8) Please use the page table on page 197 (Fig. 3.9) of the OS book to determine the physical address for the virtual address 13K. (Chapter 3)
A. 1000
B. 1K
C. 2000
D. 2K
E. Your answer: _____________
9) Which of the following statements is NOT true? (Chapter 3)
A. Given a logical address 0x7E6B (in hexadecimal) with a page size of 256 bytes, the page number is 0x7E;
B. The three-level memory hierarchy refers to cache memory, main memory, and disk storage;
C. The sizes of segments are varied and the sizes of pages are the same;
D. Process Control Blocks are used to store the program code of a running process;
E. A page fault occurs when a page referenced by a running program is not found in the memory.
10) If the memory addresses of a computer are 64 bits, its memory address space is (Chapter 1)
A. 642 bytes
B. 642 bits
C. 6410 bytes
D. 264 bits
E. 264 bytes
F. 1064 bytes
G. Your answer: ______________________________________
2.1) What is the kernel mode?
2.2) What is the user mode?
2.3) Which mode has more different instructions?
2.4) Why do we need these two modes in designing an operating system?
Explanation / Answer
Answer is as follows :
According to Chegg Guidelines we are allowed to solve only first 4 questions, so please repost others.
1) The correct option is D i.e. "It controls the flow of data between memory and some controller without constant CPU intervention."
2) The correct option s C i.e. "Processes can be created and terminated dynamically" , they can't be terminated dynamically. there is some use of processing or scheduling algorithms.
3) It is the User Programs update the Program counter. Because when user enter some program the PC is updated automatically to assign some address. So correct option is C.
4) For given scenarion Option B is correct "check how much time has been used by the current process/thread"
5) As we have 8KB frame size so we need an offset into 2000 different bytes. So (211) * 8 = 211 * 23 = 213. So 13 bits are requires for frame size offset is 13. Correct option is E. 13
6) We don't need names of processes so correct option is A.
7) The correct option is C i.e. the situation where a variable is continuously tested until some value appears.
8) In page table we have virtual address of 13k in between (12k - 16k) which is corresponding to physical address range (0k to 4k). So 13k virtual address is equal to 1k physical address. So correct option is B.
9) The correct option is C becasue saegment size and page size can varied according to requirements.
10) Memory Address space is same as memory address but in powers of 2. So memory address space for 64 bits address is 264
if there is any query please ask in comments....
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