Promote the storage management from a fixed partition to partition the dynamic allocation, which in turn developed into the main driving force paged memory management is to improve the memory utilization. You can realize a memory for multiple programs simultaneously execute without address conflict.
The purpose of introducing segmented memory management, it is mainly to meet the user (programmer) and became in use on a wide range of requirements (easy programming, information sharing, information protection, dynamic growth, dynamic link). Segment is a logical unit of memory, which has a set of meaningful and relatively complete information, a length of the segment is not fixed, depending on the program written by the user, usually divided by the compiler.
Page segments systems in order to obtain an instruction or data, a memory access times required. The first segment is accessed in the memory table access, from the start address to obtain the page table; accessing page tables in memory to access the second time, removed therefrom physical block number contained in the page, and the page address and the block number physical form of instructions or data address together; third visit real removal instructions or data resulting from the previous step address. Of course, the practical application of section has been paged system hardware support, a dedicated registers speed equipment, can greatly reduce the actual number of memory access.
Mistakes - address conversion section, when performing address translation, the segment number of the logical address system is compared with the short gage length TL, if S> TL segment number is too large, that is, access violation, an interrupt signal is generated out of range; if not out of range, then according to the start address of the segment table is calculated the segment corresponding to the segment table entry of the segment block number position, read from the start address of the segment in the memory, then the address d within the examination period exceeds section of the section long SL, if exceeded, also produced cross-border interrupt. - mistakes of the most original meaning, but behind the mistakes should be greater scope