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Summary of Section 7.1: Requirements for Efficient Memory Management

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Logical vs. Physical Memory

• Physical Memory (RAM):
  • A linear sequence of words (fixed-size data units, e.g., 1, 2, or 4 bytes).
  • Identified using physical addresses (range 0 to n-1).
• Logical Address Space:
  • An abstraction allowing programs to run independently of actual memory locations.
  • Uses logical addresses (range 0 to m-1), mapped to physical memory before execution.

Program Transformations

• Source Module: High-level program (e.g., C, Assembly).
• Object Module: Machine code output from the compiler/assembler.
• Load Module: Ready-to-execute program, created by the linker.
• Execution Process:
  • Compilation → Linking → Loading → Execution.

Relocation and Address Binding

• Relocation: Moving a program between address spaces.
• Static Relocation:
  • Logical addresses are mapped to physical addresses before execution.
• Dynamic Relocation:
  • Addresses remain logical until they are accessed at runtime.

Dynamic Relocation Using Relocation Registers

• A relocation register stores the starting physical address of a program.
• Single relocation register: Shifts all addresses in a program uniformly.