MASM Err Msg: REP OUTSW Is a 386-Only Instruction

ID Number: Q47504

5.00 5.10 | 5.00 5.10

MS-DOS | OS/2

Summary:

Using the REP OUTSW instruction generates the following error:

A2066: Must have instruction after prefix.

This problem occurs because the default assembly mode is 8086,

but the REP OUTSW is a 80386 instruction.

To enable the assembler to assemble properly, the .386 or .386P

directive must be previously placed in the source code.