Microsoft KB Archive/26616

Invalid ADC MASM Instructions Assemble with Warning Message ID Number: Q26616

5.00 MS-DOS

Problem: The MASM instructions ‘ADC eax,ax’ and ‘ADC ax,eax’, when used with the processor directive .386, will assemble with the warning ‘A4031: Operands types must match’. Both of these MASM instructions are invalid. The opcode generated is 13C0, which is the opcode for MASM instruction ‘ADC ax,ax’. MASM should not allow assembly of these instructions.

Response: MASM should generate an error in this situation, rather than a warning. This feature is under review and will be considered for inclusion in a future release.