chapter 13 - The Abstraction: Address Spaces

Question 1

what was the memory layout in the early systems

Answer 1

OS at bottom -

Question 2

what is multiprogramming

Answer 2

Keeping multiple processes in memory at once to maximize hardware usage

Question 3

what is time sharing

Answer 3

switching quickly between process for interactivity

Question 4

what is address space

Answer 4

each program sees a private view of memory - starting at 0

Question 5

main parts of address space

Answer 5

code, stack, heap

Question 6

which direction does stack and heap grow - why

Answer 6

• stack - downwards
• heap - upwards
  grows towards each other to allow flexibility

Question 7

memory virtualization

Answer 7

Translating virtual addresses (used by programs) into physical addresses (actual memory locations)

Question 8

transparancy in virtual memory

Answer 8

programs act as if they have full private memory, unaware of virtualization

Question 9

how is transparency achieved

Answer 9

The OS and hardware automatically handle virtual-to-physical address translation behind the scenes

Question 10

What is the role of protection in memory virtualization?

Answer 10

To isolate address spaces so processes cannot access each other’s memory

Question 11

How are processes isolated from one another?

Answer 11

Each process is sandboxed in its own private address space

Question 11

Why is efficiency important in memory virtualization?

Answer 11

Translation must be fast and lightweight to avoid slowing down programs