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Philips 80C51MX
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The Philips 80C51MX has a linear 16MB address space that includes the |
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standard 8051 memory areas DATA/IDATA, CODE, and XDATA. In addition |
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both the external data space and the program space can be up to 8 MB. The |
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“80C51MX Memory Layout” is shown on page 33. The LX51 linker/locater is |
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used for the Philips 80C51MX microcontroller family. The following example |
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shows assumes the following memory areas. |
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Memory Type |
Address Range |
Used by |
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ON-CHIP RAM |
7F:0000H .. 7F:03FFH |
registers, bits, variables. |
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RAM |
00:0000H .. 01:FFFFH |
EDATA space for variables. |
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ROM |
80:0000H .. 83:FFFFH |
program code and constant area. |
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To specify this memory layout LX51 should be invoked with the following |
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CLASSES directive. |
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LX51 MYPROG.OBJ CLASSES (HDATA |
(0 – 0x1FFFF), |
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EDATA |
(0x7F0000 – 0x7F03FF), |
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ECODE |
(0x800000 – 0x83FFFF), |
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HCONST |
(0x800000 – 0x83FFFF)) |
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NOTE
You need not to define the address range for the memory classes DATA, IDATA, BIT, CODE, CONST, and XDATA since the LX51 default already covers the correct physical address ranges for these memory classes.
In the AX51 assembler it is possible to use the ECODE class and therefore the complete 8MB code address space for program code. However, the CX51 compiler uses code banks to allocate parts of your program into the extended program memory. Therefore you must use same technique as described above under “Classic 8051 with Code Banking” to locate parts of your program into the ECODE space. A command line example will look as follows:
LX51 BANK0 {A.OBJ}, BANK1 {B.OBJ}, BANK2 {C.OBJ}, BANK3 {D.OBJ} CLASSES (HDATA (0 – 0x1FFFF), EDATA (0x7F0000 – 0x7F03FF),
ECODE (0x800000 – 0x83FFFF), HCONST (0x800000 – 0x83FFFF))
278 Chapter 9. Linker/Locator
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Intel/Atmel WM 251 |
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The Intel/Atmel WM 251 has like the Philips 80C51MX a linear 16MB address |
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space that includes all the memory classes. The “251 Memory Layout” is shown |
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on page 35. The following examples show you the invocation of the L251 |
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linker/locater that is used for the Intel/Atmel WM 251 microcontroller family. |
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Example 1: The following example assumes the following memory areas. |
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Memory Type |
Address Range |
Used by |
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ON-CHIP RAM |
00:0000H .. 00:041FH |
registers, bits, variables. |
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RAM |
00:8000H .. 00:FFFFH |
EDATA space for variables. |
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ROM |
FF:0000H .. FF:7FFFH |
program code and constant area. |
To specify this memory layout L251 should be invoked with the following
CLASSES directive.
L251 MYPROG.OBJ CLASSES (EDATA (0 – 0x41F, 0x8000 – 0xFFFF),
CODE (0xFF0000 – 0xFF7FFF),
CONST (0xFF0000 – 0xFF7FFF))
NOTES
You need not to define the address range for the memory classes DATA, IDATA, BIT and EBIT since the L251 default already covers the correct physical address ranges for these memory classes.
This example assumes that the memory classes XDATA, HDATA, HCONST,
HCODE, and NCONST are not used in your application.
Keil Software — A51/AX51/A251 Macro Assembler and Utilities |
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Example 2: In addition to the example above, the next system contains a third RAM for the memory class XDATA. In addition the ROM space is increased.
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Memory Type |
Address Range |
Used by |
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ON-CHIP RAM |
00:0000H .. 00:041FH |
registers, bits, variables. |
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ROM |
00:0420H .. 00:7FFFH |
NCONST space. |
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RAM |
00:8000H .. 01:7FFFH |
EDATA/HDATA space for variables. |
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ROM |
FE:0000H .. FF:FFFFH |
program code and constant area. |
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To specify this memory layout L251 should be invoked with the following CLASSES directive.
L251 MYPROG.OBJ CLASSES (EDATA (0 – 0x41F, 0x8000 – 0xFFFF),
NCONST (0x420 – 0x7FFF),
HDATA (0x8000-0x1FFFF),
HCONST (0xFE0000 – 0xFFFFFF),
ECODE (0xFE0000 – 0xFFFFFF))
NOTE
You need not to define the address range for the memory classes DATA, IDATA, BIT, EBIT, CODE, CONST, and XDATA since the L251 default already covers the correct physical address ranges for these memory classes.