Memory addresses are assigned by the operating system, which manages the computer's memory. The OS uses a memory management unit (MMU) to translate logical addresses used by programs into physical addresses used by the hardware.
Here's how it works:
- Logical Addresses: These are the addresses used by programs to access data. They are assigned during program compilation and are relative to the start of the program's memory space.
- Physical Addresses: These are the actual addresses of memory locations in the computer's hardware. They are assigned by the MMU based on the logical address and the current state of memory.
Memory Allocation Techniques
There are different techniques used to allocate memory addresses, including:
- Static Allocation: Memory is assigned to programs at compile time, meaning the amount of memory each program needs is fixed. This is simple to implement but can lead to memory fragmentation if programs don't use all allocated memory.
- Dynamic Allocation: Memory is assigned to programs at runtime, meaning programs can request memory as needed. This is more flexible but can be slower and more complex to manage.
Memory Mapping
The MMU uses a memory map to translate logical addresses to physical addresses. This map is a table that stores the current allocation of memory locations.
Examples
- Example 1: A program requests 100 bytes of memory. The OS finds a free block of memory with 100 bytes available and assigns it to the program. The MMU then creates a mapping between the program's logical address for the first byte (e.g., address 0) and the physical address of the first byte of the allocated block.
- Example 2: A program needs to access a file on disk. The OS loads the file into memory and assigns it a logical address. The MMU then maps this logical address to a physical address in the computer's RAM.
Conclusion
Memory addresses are assigned by the operating system using a memory management unit to ensure efficient use of memory resources and prevent conflicts between programs. This process is crucial for the smooth operation of a computer system.
