osoitteenkäännöksiä

Osoitteenkäännökset, known in English as Address Translation, is a fundamental process in computer operating systems. It refers to the mechanism by which logical addresses generated by a program are converted into physical addresses in main memory. This translation is typically handled by the hardware's Memory Management Unit (MMU).

The primary purpose of address translation is to provide memory protection and enable efficient memory utilization. By abstracting the physical memory layout from the programs, each process can operate as if it has its own dedicated memory space, preventing interference with other processes. This also allows for the implementation of virtual memory, where the system can use secondary storage like a hard disk as an extension of RAM, enabling the execution of programs larger than the available physical memory.

Common techniques for address translation include paging and segmentation. In paging, memory is divided into fixed-size blocks called pages, and the logical address is split into a page number and an offset. A page table, maintained by the operating system, maps these logical page numbers to physical frame numbers. Segmentation, on the other hand, divides memory into variable-sized logical units called segments, each representing a logical part of a program like code or data. The logical address then consists of a segment number and an offset within that segment. Modern systems often combine these techniques.