Article ID: 34985
Article Last Modified on 10/16/2003
APPLIES TO
- Microsoft Macro Assembler 5.1 Standard Edition
This article was previously published under Q34985
SYMPTOMS
The Microsoft Macro Assembler (MASM) versions 5.1 and 5.1a will generate a warning for the following sample code, while MASM version 6.0, 6.0a, and 6.0b will assemble it without error. The warning generated by 5.1 and 5.1a is as follows
The linkers that shipped with both products (versions 3.64 and 5.13, respectively) will report the following error at link time
CAUSE
Warnings are generated because code segments in the range of 65,501 - 65,536 bytes may be unreliable on certain 80286 processors.
MORE INFORMATION
The size of a 16-bit segment is limited to 64K. The recommendation of having segments no larger than 65,500 (64K-36) is to avoid problems with certain 80286 processors.
When the segment really does exceed 64K, MASM 5.1 and 5.1a generate an error rather than a warning
and MASM 6.0, 6.0a, 6.0b generates an error as well
The following sample code will cause MASM to generate warnings, since the segment size is between 65,501 and 65,536 bytes. Increasing the size of 'value' to 65,550 will result in errors rather than warnings.
Sample Code
; Assemble options needed: none
.model small,c
.286
.stack
.code
start:
MOV ax, @data
MOV ds, ax
value db 65500 dup ( ? )
MOV ah, 4ch
INT 21h
END start
Additional query words: 5.10
Keywords: KB34985
