UNIT III: Memory-Management Strategies: Introduction, Swapping, Contiguous memory allocation,
Paging, Segmentation. Virtual Memory Management: Introduction, Demand paging, Copy on-write,
Page replacement, Frame allocation, Thrashing, Memory-mapped files, Kernel memory allocation.
Memory Management
Introduction:
1.Basic Hardware
2.Address Binding:
3.Logical Versus Physical Address Space
4.Dynamic loading
5. Dynamic Linking and Shared Libraries
1.Basic Hardware
• Main memory and the registers built into the processor itself are the only general-purpose
storage that the CPU can access directly.
• There are machine instructions that take memory addresses as arguments, but none that
take disk addresses.
• If the data are not in memory, they must be moved there before the CPU can operate on
them.
• We first need to make sure that each process has a separate memory space. Separate per-
process memory space protects the processes from each other
• We can provide this protection by using two registers,
1.base Register
2.Limit Register
• The base register ------------holds the smallest legal physical memory address/Starting
address of the register
• The Limit Register------specifies the size of the range
