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Accessing Registers without the 'reg' Prefix

Last Updated: March 27, 2011

What happens when I write an assembly code to access a register without the "reg" keyword, for example, "mov A, [PRT1DR]". Does the assembler generate an error for this?


No. The assembler does not generate an error or warning if a register is accessed without the "reg" keyword.  The register name defined in the file is only an address equate.  So, if the assembler comes across an instruction with a register name, but without the "reg" keyword, it replaces the register name with the address of the register and the CPU will perform a RAM access instead of register access.

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