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Applies to: A251 Macro Assembler
Information in this article applies to:
I'm using the 251 microcontroller with a 27C256 (32K EPROM) and I need to know where I should locate the configuration bytes in the START251.A51 startup code file.
The configuration bytes are located at FF:FFF8h and FF:FFF9h. However, since the 32K EPROM does not extend that high in memory, the config bytes must be located at the addresses read when FF:FFF8h and FF:FFF9h are asserted on the address bus.
In the 32K EPROM, these addresses are 7FF8h and 7FF9h. The code in START251.A51 should appear as follows:
$IF (CONFIGB) CONFIG0 EQU (WSA*20H)+(XALE*10H)+(RDRG*4)+(PAGM*2)+SRCM+080H CONFIG1 EQU (INTR*10H)+(EDF*8)+(WSB*2)+EMAP+0E0H CSEG AT 07FF8H DB CONFIG0 ; Config Byte 0 DB CONFIG1 ; Config Byte 1 $ENDIF
Article last edited on: 2005-02-23 11:37:44
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