читаем Assembler HelpEQU - Set a symbol equal to an expression
The EQU directive assigns a value to a label. This label can then be used in later expressions. A label assigned to a value by the EQU directive is a constant and can not be changed or redefined.
Syntax:
.EQU label = expression
Example:
.EQU io_offset = 0x23
.EQU porta = io_offset + 2
.CSEG ; Start code segment
clr r2 ; Clear register 2
out porta,r2 ; Write to Port A