masm5.0-dosbox0.74-MasmForWindows.zip

Microsoft Macro Assembler Package

Version 5.00

Text files on the Macro Assembler disks are tabbed to save

disk space. If your printer does not automatically handle

tabs during printing, you must use a print program that

expands tabs. For example, use the DOS PRINT program to print

this and other document or source files on the disk.

Note to DOS 3.0 Users

Because of an incompatibility between DOS 3.0 and the batch

The /LA option has been added to specify a complete listing

of all symbols, macros, and false conditionals. It is

equivalent to using the .LIST, .LFCOND, .LALL, and .CREF

directives throughout the source file. The option overrides

any conflicting directives in the source file.

Clarification

The PTR operator can be used to specify the size of a

register indirect operand for a CALL or JMP instruction.

However, the size cannot be specified with NEAR or FAR. Use

WORD or DWORD instead. (In 80386 32-bit segments, use DWORD

; 80386 32-bit mode only

jmp DWORD PTR [bx] ; Legal near jump

call NEAR PTR [bx] ; Illegal near call

call FWORD PTR [bx] ; Legal far call

jmp FAR PTR [bx] ; Illegal far jump

This limitation only applies to register indirect operands.

NEAR or FAR can be applied to operands associated with

labels. Examples are shown below:

jmp NEAR PTR pointer[bx] ; Legal

call FAR PTR location ; Legal

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Correction

When evaluating expressions, MASM does 16-bit arithmetic except

when the 80386 processor is enabled. If the .386 or .386P

directive has been given, MASM does 32-bit arithmetic. This

behavior is consistent with earlier versions of MASM, which

9.2.1.5 of the Programmer's Guide are incorrect. They should say

EXTRN fvar:WORD ; FAR variable in far

.CODE

start: ASSUME es:SEG fvar ; Tell the assembler

mov ax,SEG fvar ; Tell the processor

mov es,ax

This is the same limitation described for communal variables

in Section 8.4. The reason is that under the DOS segment

conventions, multiple far data segments share the same name

(FAR_DATA) and have private combine type. Segments with the

same name can only be distinguished indirectly using the SEG

Correction

Public absolute symbols must be declared during pass 1.

This

means that aliases for absolute symbols or other forward

references to them will cause errors. For example, the

following code generates an error:

PUBLIC lines

lines EQU rows

rows EQU 25