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@c  memmodel.t,v 1.6 2002/01/17 21:47:46 joel Exp

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@chapter Memory Model

@section Introduction

A processor may support any combination of memory

models ranging from pure physical addressing to complex demand

paged virtual memory systems.  RTEMS supports a flat memory

model which ranges contiguously over the processor's allowable

address space.  RTEMS does not support segmentation or virtual

memory of any kind.  The appropriate memory model for RTEMS

provided by the targeted processor and related characteristics

of that model are described in this chapter.

@section Flat Memory Model

The i960CA supports a flat 32-bit address space with

addresses ranging from 0x00000000 to 0xFFFFFFFF (4 gigabytes).

Although the i960CA reserves portions of this address space,

application code and data may be placed in any non-reserved

areas.  Each address is represented by a 32-bit value and is

byte addressable.  The address may be used to reference a single

byte, half-word (2-bytes), word (4 bytes), double-word (8

bytes), triple-word (12 bytes) or quad-word (16 bytes).  The

i960CA does not support virtual memory or segmentation.

The i960CA allows the memory space to be partitioned

into sixteen regions which may be configured individually as big

or little endian.  RTEMS assumes that the memory regions in

which its code, data, and the RTEMS Workspace reside are

configured as little endian.