Resources: Memory

Question 1

what is memory made up of

Answer 1

addresses and data

Question 2

what is an address space

Answer 2

the number of possible locations that could be addressed

Question 3

what is RAM

Answer 3

random access memory, main memory, allows any address to be read

Question 4

what is DMA

Answer 4

direct memory access

there is a DMA controller than is a simple processor capable of moving data from place to place.

works on physical addresses as outside of MMU

Question 5

what are the OS’s jobs when it comes to memory

Answer 5

manage access permissions

deal with heap/stack overflow

keep track of progress of a process

create segments

Question 6

what is memory mapping

Answer 6

translate virtual addresses into physical addresses using page table

Question 7

how to two level page tables work

Answer 7

subdivide page tables into a tree structure.

Second level page table sdont have to be in RAM, they can be on disk. this allows us to access more addresses.

instead of our address being split into page and offset, it is split into first page, second page and offset.

Question 8

describe memory segments

Answer 8

contiguous, variable size chunks of memory. each segment has a number, length and base address

Question 9

what is dynamic memory allocation

Answer 9

memory allocated at run time

Question 10

what is stored when we declare an array

Answer 10

the size of the array

and a pointer to the first element