MASM MUL Operation Accepts Only One Operand

Last reviewed: January 23, 1995
Article ID: Q74882

The information in this article applies to:

Microsoft Macro Assembler for MS-DOS, versions 5.1, 5.01a, and 6.0
Microsoft Macro Assembler for OS/2, versions 5.1, 5.01a, and 6.0

SUMMARY

The assembly language multiplication instruction MUL accepts only one operand. The second operand is implied to be either the AX or the AL register depending on whether an 8-bit multiplication or 16-bit multiplication is being performed.

If a second operand is specified, the Microsoft Macro Assembler (MASM) version 6.0 will generate the following error:

   error A2008: syntax error : ,

MASM versions 5.1 and 5.1a generate the following warning:

   warning A4001: Extra characters on line

MORE INFORMATION

The sample code below can be used to illustrate this situation. Assembling the code with MASM version 5.1, 5.1a, or 6.0 will result in one of the above errors.

Sample Code

; Assemble options needed: none

    .MODEL small
    .CODE
    mul ah, 10
    END

Additional reference words: kbinf 5.10 5.10a 6.00 6.00a 6.00b
KBCategory: kbprg
KBSubCategory: MASMLngIss

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Last reviewed: January 23, 1995
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