Address spaces and segments, Allocating processor memory, Address spaces – Zilog ZUSBOPTS User Manual
Page 240: Allocating processor memory address spaces, Table 18, Zneo address spaces
Address Spaces and Segments
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Zilog Developer Studio II – ZNEO™
User Manual
Address Spaces and Segments
The ZNEO architecture divides all memory into multiple memory regions which are
depicted by address spaces in the assembler. Each address space can have various seg-
ments associated with it. A segment is a contiguous set of memory locations within an
address space. The segments can be predefined by the assembler or user-defined.
Allocating Processor Memory
All memory locations, whether data or code, must be defined within a segment. There are
two types of segments:
Absolute segments.
An absolute segment is any segment with a fixed origin. The origin
of a segment can be defined with the ORG directive. All data and code in an absolute seg-
ment is located at the specified physical memory address.
Relocatable segments.
A relocatable segment is a segment without a specified origin. At
link time, linker commands are used to specify where relocatable segments are to be
located within their space. Relocatable segments can be assigned to different physical
memory locations without re-assembling.
Address Spaces
The assembler provides the address spaces listed in Table 18, which represent the memory
regions of the ZNEO microcontroller.
Code and data are allocated to these spaces by using segments attached to the space.
Table 18. ZNEO Address Spaces
Space ID
Description
ROM
16-bit addressable read-only memory.
RAM
16-bit addressable read/write memory.
EROM
32-bit addressable code memory.
ERAM
32-bit addressable extended memory.
IODATA
16-bit addressable IO data memory.