Memory System Design II - Fundamentals of Computer Organization and Architecture - page 153

Figure 7.17 Memory hierarchy accesses scenarios

scenario will require updating the page table, the main memory, and the cache. A
subsequent request of that virtual address by the processor will result in updating
the TLB.

7.2.7. Segmentation

A segment is a block of contiguous locations of varying size. Segments are used by
the operating system (OS) to relocate complete programs in the main and the disk
memory. Segments can be shared between programs. They provide means for pro-
tection from unauthorized access and or execution. It is not possible to enter seg-

ments from other segments unless the access has been specifically allowed. Data
segments and code segments are separated. It should also not be possible to alter
information in the code segment while fetching an instruction nor should it be poss-
ible to execute data in a data segment.

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7.2.8. Segment Address Translation

In order to support segmentation, the address issued by the processor should consist
of a segment number (base) and a displacement (or an offset) within the segment.
Address translation is performed directly via a segment table. The starting address
of the targeted segment is obtained by adding the segment number to the contents
of the segment table pointer. One important content of the segment table is the