376 datasheet(11/95 Pages) INTEL

11 / 95 page

376 EMBEDDED PROCESSOR

240182 – 6

Figure 23 Address Translation

SEGMENT REGISTER USAGE

The main data structure used to organize memory is

the segment On the 80376 segments are variable

sized blocks of linear addresses which have certain

attributes associated with them There are two main

types of segments code and data The simplest use

of segments is to have one code and data segment

Each segment is 16 Mbytes in size overlapping each

other This allows code and data to be directly ad-

dressed by the same offset

In order to provide compact instruction encoding

and increase processor performance instructions

do not need to explicitly specify which segment reg-

ister is used The segment register is automatically

chosen according to the rules of Table 23 (Segment

ences use the selector contained in the DS register

stack references use the SS register and instruction

fetches use the CS register The contents of the In-

struction Pointer provide the offset Special segment

override prefixes allow the explicit use of a given

segment register and override the implicit rules list-

ed in Table 23 The override prefixes also allow the

use of the ES FS and GS segment registers

There are no restrictions regarding the overlapping

of the base addresses of any segments Thus all 6

segments could have the base address set to zero

Further details of segmentation are discussed in

Section 30 Architecture

376 Folha de dados(PDF) 11 Page - Intel Corporation