Logical Address vs Physical Address - aryanjoshi0823/5143-Operating-System GitHub Wiki
- A logical address is a virtual address generated by the CPU while a program is running.
- It does not physically exist and serves as a reference to access the physical address in memory.
- The Memory Management Unit (MMU) maps logical addresses to physical addresses.
- The collection of all logical addresses for a program forms the logical address space.
- A physical address is the actual address of data stored in the memory.
- The user program generates logical addresses, which the MMU translates into physical addresses for execution.
- The collection of all physical addresses mapped from logical addresses constitutes the physical address space.
| Aspect | Logical Address | Physical Address |
|---|---|---|
| Definition | A virtual address generated by the CPU. | The actual location in physical memory. |
| Visibility to User | Not visible to the user. | Visible to the user. |
| Generation | Created by the CPU. | Computed by the MMU. |
| Purpose | Used by the user to reference memory. | Used to access actual data in memory. |
| Address Space | Forms the logical address space. | Forms the physical address space. |
| Accessibility | Accessed indirectly via MMU. | Not accessible directly by the user. |
- The logical address space is the set of all logical addresses generated by the CPU for a program.
- The physical address space is the set of physical addresses corresponding to these logical addresses.
- The MMU bridges the gap between logical and physical addresses, ensuring proper memory mapping.