Block-based page-based storage management (I)

 

First, let's take a look at the definition of segment-based storage.

Page Storage Management:

Based on this concept, page-based storage allocation divides incoming jobs into pages of the same size. The size of some Operating System Selection pages is allocated based on the size of the storage block and the size of some areas of the disk stored by the job. Generally, they are equal.

Segmented Storage Management:

It refers to dividing a program into several segments for storage. Each segment is a logical entity. Programmers need to know and use it. Each segment has a complete logical meaning, so it can be programmed independently, and each segment is given a segment name.

 

Segment-and-page storage management:

The basic principle of the segment-PAGE system is the combination of the basic Segment Storage Management Mode and basic paging storage management mode, that is, the user program is first divided into several segments, divide each segment into several pages and assign a segment name to each segment.

Logical Address and physical address transformation process

When a job instruction is executed, the field number (segment I in the figure) in the logic address of the instruction queries the job field table to obtain the first address of the page table of the job segment, query the page table by the page number in the instruction logical address to obtain the memory block number corresponding to the page. Finally, combine the unit number of the block number and the logic address in the instruction into an absolute address, this address is the absolute address of the memory to be accessed. If this absolute address is in the storage area of this segment, it can be accessed; otherwise, an address out-of-bounds interruption occurs.