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80C186EC/80C188EC Microprocessor User's Manual

80C186EC/80C188EC Microprocessor User's Manual

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OVERVIEW OF THE 80C186 FAMILY ARCHITECTURE<br />

2.1.7 Memory Segmentation<br />

Programs for the 80C186 Modular Core family view the 1 Mbyte memory space as a group of<br />

user-defined segments. A segment is a logical unit of memory that can be up to 64 Kbytes long.<br />

Each segment is composed of contiguous memory locations. Segments are independent and separately<br />

addressable. Software assigns every segment a base address (starting location) in memory<br />

space. All segments begin on 16-byte memory boundaries. There are no other restrictions on segment<br />

locations. Segments can be adjacent, disjoint, partially overlapped or fully overlapped (see<br />

Figure 2-6). A physical memory location can be mapped into (covered by) one or more logical<br />

segments.<br />

2-8

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