FIX: MASM Moves Segment Register w/out Generating Error (83087)

The information in this article applies to:

Microsoft Macro Assembler (MASM) 6.0
Microsoft Macro Assembler (MASM) 6.0a
Microsoft Macro Assembler (MASM) 6.0b
Microsoft Macro Assembler (MASM) 6.1
Microsoft Macro Assembler (MASM) 6.1a

This article was previously published under Q83087

SYMPTOMS

Microsoft Macro Assembler (MASM) may move a segment register instead of generating an error on an invalid code statement. In the following example, the statement:

   mov bx, es[1234h]

should generate an error. However, MASM treats the statement as:

   mov bx, es

and thus does not generate the code that may be expected. The code that the user anticipated being generated was:

   mov bx, es:[1234h]

STATUS

Microsoft has confirmed this to be a problem in MASM versions 6.0, 6.0a, 6.0b, 6.1, and 6.1a. This problem was corrected in MASM for MS-DOS version 6.11.

MORE INFORMATION

The following program should generate two assembler errors but does not:

Sample Code

; Assemble options needed: none

.MODEL small
.386
.STACK 4096

.CODE
start:
   mov bx,es[1234h]     ; This should generate an error.
   mov es[1234h],bx     ; This should generate an error.
   mov ax, 4C00h
   int 21h
END start

Modification Type:	Major	Last Reviewed:	10/29/2003
Keywords:	kbfix KB83087