Basics of memory: no abstraction

memory address space: addresses from first byte to last byte. in physical memory, it’s physical memory address space.

no memory abstraction: monoprogramming

options of arranging memory address space:

no memory abstraction: multiprogramming

• naive approach: move each program to a dedicated region:

  

  • problems:
    • relocation - you have to move to a completely different address.
      • load-time relocation option — as soon as program is loaded, patch all addresses with new ones
    • protection - both programs live together in memory. one program could overwrite the other
      • memory keys option — current memory protection key gets checked against memory protection key of address