Zilog ZUSBOPTS Manual de usuario descargar pdf (Pagina 335)

100

101

UM017105-0511 Programmer’s Model of ZNEO Memory

Zilog Developer Studio II – ZNEO™

User Manual

307

The following default segments are provided by the assembler and associated with spe-

cific address spaces as shown in the following table:

For a detailed description of these segments, see the Predefined Segments

section on

page 213.

You can define your own segments in these address spaces using the DEFINE assembler

directive. For example:

DEFINE romseg, SPACE=ROM ; Defines the new segment romseg

SEGMENT romseg ; Sets the current segment to romseg

See the User-Defined Segments section on page 213 for further details.

Unconventional Memory Layouts

It might be necessary for a target design to locate memory or I/O in an address range that

the ZDS II GUI does not directly accommodate. Some GUI address range limitations can

be circumvented, as follows:

•

The GUI rejects an ERAM range lower boundary setting below 80_0000H. If the tar-

get locates external volatile memory below this address, an unrestricted ERAM range

can be configured by adding an edited linker RANGE command to the

Additional

Linker Commands

field of the ZDS II project settings. For example, if the target pro-

vides 8MB of extended RAM at address

70_0000H, you would use this command:

RANGE ERAM $700000 : $FEFFFF

•

The GUI rejects a RAM range upper boundary setting above FF_BFFFH. If the target

uses the space above this address for external volatile memory instead of external I/O,

a higher RAM upper boundary (up to

FF_DFFFH) can be configured by adding an

edited linker RANGE command to the

Additional Linker Commands field of the

ZDS II project settings. The debugger memory window always displays addresses

above

FF_BFFFH as part of the I/O Data space, however. For example, if the target

provides 24KB of combined internal and external RAM beginning at

FF_8000H, you

would use this command:

RANGE RAM $FF8000 : $FFDFFF

Address

Range (Space) Segment

ROM ROM_DATA, ROM_TEXT, __VECTORS

EROM CODE, EROM_DATA, EROM_TEXT

RAM NEAR_DATA, NEAR_BSS, NEAR_TEXT

ERAM FAR_DATA, FAR_BSS, FAR_TEXT

IODATA IOSEG

1 2 ... 330 331 332 333 334 335 336 337 338 339 340 ... 519 520

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