Quiz 12.4

DIRECTIONS: Read each question carefully. Then click on the dot next to the answer that most closely fits the question. Try to answer all questions on this quiz and when you are done, click on the grade me button at the bottom.

Coverage: Section 12.5

  1. What is a virtual address space?
a set of numbers that are the addresses that the actual memory hardware recognizes
a set of numbers that are the addresses that the running program could generate
a set of numbers that are the addresses of pages currently residing in real memory frames

  1. Addresses that user programs can generate in the VAX are 31 bits long. How big is the virtual address space?
about 2 billion bytes
about 2 billion words
about 2 billion pages
about 2 billion frames

  1. What enables the translation of virtual addresses into real addresses?
the memory decoder
the page table
the active job table
the operating system

  1. If a computer system could have N bytes of real memory, is it likely to have that much real memory?
always
sometimes but not always
never because virtual address spaces are billions to trillions of bytes long

  1. Which of the following fields is usually not found in a page table?
present/absent bit
dirty bit
physical frame number where the page currently resides
disk address
process id number

  1. Which piece of data in the page table is of importance when the page is not currently in physical memory?
the dirty bit
the frame number
the disk address

  1. What happens when the program accesses a byte in a page that is currently not in memory?
the program is interrupted and the OS is asked to put the page into a frame
the program terminates with a fatal error
the program continues on with the program while the OS loads the page into a frame
the OS marks the job as ready to run and schedules it to continue execution

  1. How long are disk addresses?
longer than any memory address
about as long as virtual memory addresses
shorter than virtual memory addresses
about as long as real memory addresses

  1. What significance does the frame number have when the dirty bit is on?
it is used to store the disk address where the page actually resides
it tells which byte was last changed
it is used as a timestamp to tell when this frame was last changed
none

  1. What do we call the event when a page is referenced that is not currently in physical memory?
a timeout
a page fault
an abend
an interrupt

  1. Which of the following components of a disk address below is usually not of importance in virtual memory systems?
disk drive number
sector number
track number
byte within sector
platter or surface number