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Predefined Macros

The A251 Assembler provides the following predefined constants you may use in preprocessor directives and assembler code to create portable programs.

Constant Description
__A251__ Version number of the A251 Assembler (for example, 212 for version 2.12).
__DATE__ Date when the assembly was started in ANSI format (month dd yyyy).
__DATE2__ Date when the compilation was started in short form (mm/dd/yy).
__FILE__ Name of the file being assembled.
__KEIL__ Set to 1 to indicate the KEIL A251 Assembler.
__LINE__ Current line number in the file being assembled.
__MOD_SRC specifies that the assembler generate code for 251 source mode with the MOD_SRC Assembler Directive.
__TIME__ Time when the assembly was started.


  • There are two (2) leading and trailing underscore characters ('_') used for the predefined constants.
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