README.TXT File
Release Notes for the Microsoft(R) MASM
Professional Development System, Version 6.11
(C) Copyright 1993, Microsoft Corporation. All rights reserved.
This document contains release notes for the Microsoft MASM
Professional Development System, version 6.11. The information in
this document and in the Microsoft Advisor (online help) is more
up-to-date than that in the manuals.
The printed documentation for MASM 6.11 has not changed from MASM 6.1.
The MASM 6.11 installation disks provide several important files that
include new or updated information for this release. They are:
README.TXT =====> Contains documentation errata, system requirements,
information and tips on using MASM 6.11, and known
assembler bugs.
PENTIUM.TXT ====> Contains .586 and .586P directives information,
descriptions of the new Intel(R) Pentium(TM)
instructions, and a table of Pentium timings for all
instructions.
CV.TXT =========> Contains release notes for Microsoft CodeView(TM).
ERRMSG.TXT =====> Contains updated information on 32-bit Linker errors,
ML error messages, and Microsoft DOSXNT MS-DOS
Extender error messages.
SAMPLES.TXT ====> Contains information about MASM samples for MS-DOS
and Microsoft Windows 3.1.
NTSAMPLE.TXT ===> Contains information about MASM samples for
Microsoft Windows NT.
SUPPORT.TXT ====> Contains updated Microsoft Product Support policies.
======================< README.TXT Table of Contents >=====================
Part 1: Documentation Errata
----------------------------
Part 2: System Requirements
---------------------------
Part 3: Tips for Using MASM 6.1x
--------------------------------
- ALIAS directive
- Assembling Files Generated by Compiler
- Building 32-Bit Applications
- 32-Bit Linking
- GROUP Directive and Flat-Model Programming
- Structure Packing Issues for Mixed Language Programming
- /WIN32 Switch for H2INC
- CD-ROM Not a Valid Target
- CMP Instruction Encoding
- Debugging MASM Applications under Visual C++, 32-Bit
Edition, or Fortran PowerStation, 32-Bit Edition
- .FPO Directive
- INVOKE Command
- LINK and System Resources
- MOUSE.COM
- MS-DOS and Windows NT File Compatibility
- Multi-File Assembly with MASM.EXE
- NMAKE and NMAKER
- Response Files
- SAMPLES.TXT and NTSAMPLE.TXT
- Using Control-C to Halt Operation of MASM
- Using MASM 6.x Structures
- Visual C++ 1.0/Fortran PowerStation 1.0 Compatibility
- Working with MASM 5.1 Code
- Working With Microsoft BASIC Far Strings
Part 4: Known Assembler Bugs
----------------------------
- Exiting from MS-DOS Critical Errors
- Expression Order in High-Level Conditionals
- Hexadecimal Constants
- Initializing Nested Structures
- Intersegment Near Jumps in Flat Model
- Span-Dependent Expressions used in Macros
- Span-Dependent Equates in Macros and EXTERNDEF ABS
- Span-Dependent Text Equates
- STRUCT and RECORD Initialization
- Using The /link /nologo Command Line Options
====================< Part 1: Documentation Errata >=======================
Environment and Tools, Page xxiii: Microsoft Support Services
-------------------------------------------------------------
Microsoft Support Services information has been updated. See
SUPPORT.TXT, in the directory in which you installed MASM, for
the most current Microsoft support information and policies.
Environment and Tools, Page 582: LIB Command Line Sample
--------------------------------------------------------
The following example, as it appears on page 582, is incorrect:
LIB FIRST +SECOND, , THIRD
It should instead read:
LIB THIRD +FIRST +SECOND
Environment and Tools, Page 649, 651: _syscall and __syscall
------------------------------------------------------------
The H2INC documentation on pages 649 and 651 lists _syscall and
__syscall as C keywords recognized by H2INC. These are not recognized,
and should be removed.
Environment and Tools, Page 819: Error Message A2156
----------------------------------------------------
The value range given for the first parameter of the PAGE directive
is incorrect; "...either 0 or a value in the range of 10-255" should
read "...either 0 or a value in the range of 14-255."
Reference, Page 12: ML Command-line Options /Cu and /Cx
-------------------------------------------------------
/Cu is not the default command-line option, but is indicated as such
in the MASM 6.1 Reference. Instead, /Cx should be indicated as the
default.
Reference, Page 98: LEA is no longer optimized
----------------------------------------------
The MASM 6.1 Reference indicates that the LEA instruction is
encoded as a MOV when the source operand is a direct memory address.
In response to programmer requests, MASM 6.1x no longer performs this
optimization automatically. The optimization can be performed by
using the OPATTR operator, as shown in the following macro:
MOVLEA MACRO Dest, Symbol
IF (OPATTR(Symbol)) AND 08h
MOV Dest, OFFSET Symbol
ELSE
LEA Dest, Symbol
ENDIF
ENDM
Programmer's Guide, Page 156: Using an Emulator Library
-------------------------------------------------------
The sample code demonstrating floating-point instructions served
by an emulator contains the directive .STARTUP. This directive
should be removed.
Programmer's Guide, Page 202: User-Defined Epilogues & Prologues
----------------------------------------------------------------
The documentation for user-defined epilogue and prologue code reads
"Your macro function must return the parmbytes parameter." It
should read "...the localbytes parameter."
Programmer's Guide, Page 323: The C++/MASM Interface
----------------------------------------------------
The second sentence in the third paragraph reads: "The linkage
specification applies only to called routines, not to external
variables." It should read "The linkage specification applies to
called routines and external variables." The last sentence in the
same paragraph should be removed.
Help for Runtime Error R6921
----------------------------
The online help for runtime error R6921 reads "...Possibly the
CONFIG.SYS file contained a line such as DEVICE=C:\OS\MM386.EXE..."
The file name should read "C:\DOS\EMM386.EXE".
=================< Part 2: MASM 6.11 System Requirements >=================
The following are system requirements for Microsoft MASM 6.11:
- Personal computer using a 386 or higher processor running MS-DOS
version 3.3 or later, Windows version 3.1 or later, or Windows NT
version 3.1 or later.
- 4 MB of available memory.
- Hard disk with 10 MB available space.
- One 3.5" high-density (1.44 MB) disk drive (3.5" low-density (720K)
or 5.25" high-density (1.2 MB) disks available separately with
coupon enclosed).
To target Windows 3.1, you need one of the following:
- Microsoft Windows Software Development Kit (SDK) 3.1.
- Microsoft Visual C++ Development System, Standard or Professional
Edition.
To target Windows NT, you need one of the following:
- Microsoft Windows NT Software Development Kit (SDK).
- Microsoft Visual C++ Development System, 32-Bit Edition.
====================< Part 3: Tips for Using MASM 6.11 >===================
ALIAS directive
---------------
The ALIAS directive is not included in the printed documentation
for MASM 6.11. The ALIAS directive can be used for creating
libraries that allow the linker (LINK) to map an old function to
a new function.
Syntax: ALIAS <alias> = <actual-name>
where alias is the alternate or alias name, and actual-name is
the actual name of the function or procedure. The angle brackets
are required.
The ALIAS directive should be used with LINK 5.3 or later and LIB
3.2 or later. At this time, ALIAS functions only with the 16-bit
linker.
Assembling Files Generated by Compilers
------------------------------------------
Many compilers support assembly-language output. If you experience
difficulty assembling the output of such compilers, you may need to
assemble using the /Zm option. In some cases (for instance, if the
compiler inserts nondelimited comments or page numbers) it may be
necessary to edit the assembly-language output by hand.
Building 32-bit Applications
----------------------------
Following are a number of items you should keep in mind when
building 32-bit applications with MASM 6.11. Examples of how to
create 32-bit applications can be found in the \SAMPLES\NTSAMPLE
subdirectory of the directory in which you installed MASM.
32-bit Linking
--------------
When you are creating a 32-bit application, you must link
separately with a 32-bit linker. To prepare your object files
for 32-bit linking, assemble using the following switches:
- /c (assembles without linking)
- /coff (causes object files to be created in Windows NT-
compatible common object file format)
After assembling, link with your 32-bit linker. Refer to the
documentation included with your particular 32-bit linker for
specific information and instructions. In addition, the sample
NT applications in \SAMPLES\NTSAMPLE demonstrate the use of
/c, /coff, and a 32-bit linker.
GROUP Directive and Flat-Model Programming
------------------------------------------
The GROUP directive has no effect when used in 32-bit flat-model
programming. It is recommended that you not use the GROUP
directive when programming in flat model.
Structure Packing Issues for Mixed Language Programming
-------------------------------------------------------
Microsoft MASM uses /Zp1 as it's default setting for structure
packing; this means that structures are not packed. Other
languages may use other default settings for packing. For
example, Microsoft C/C++ compilers prior to Visual C++ 32-bit
edition use /Zp2; Visual C++ 32-bit edition uses /Zp8 as the
default. Modules built using different structure packing may not
be able to share structure data items, so care must be taken
when using structures in mixed language programs.
The packing size is a maximum, not a fixed, packing value. This
means that a member must have a size equal to or larger than the
packing limit before any packing is done. In many cases, using
/Zp4 on assembly modules will allow them to work with other
modules compiled with /Zp8 if none of the members have a size
larger than 4 bytes. Doubles, long doubles, and member structures
larger than 4 bytes will cause problems. If a structure contains
members larger than 4 bytes you will need to pack the structure
yourself by adding "dummy" data items.
/WIN32 Switch for H2INC
-----------------------
Use the /WIN32 switch with H2INC to convert C header files to
NT-compatible MASM include files. When you use the /WIN32 switch,
C int data types are converted to the 4-byte assembler equivalent
DWORD (signed int data types are converted to SDWORD). Without
the /WIN32 switch, H2INC converts int data types to 2-byte WORD
(and signed int data types to SWORD).
CD-ROM Not a Valid Target
-------------------------
A CD-ROM drive is not a valid installation target for MASM 6.11.
CMP Instruction Encoding
------------------------
MASM 6.1x uses a different encoding for the CMP <reg8>,<reg8>
instruction than MASM 6.0 did. There is no difference in length or
processor timing.
Debugging MASM Applications under Visual C++, 32-bit Edition,
or Fortran PowerStation, 32-bit Edition
-------------------------------------------------------------
When debugging a pure MASM application under the 32-bit editions of
Visual C++ or Fortran PowerStation, you must link in the library
file (.LIB) provided with these high-level languages (LIBC.LIB in
Visual C++, LIBF.LIB with Fortran PowerStation), instead of the one
included with MASM 6.11. If you do not use the .LIB file included in
the high-level language, you will receive an "Access Violation"
error message when you attempt to run a MASM application in either
the 32-bit Visual C++ or 32-bit Fortran PowerStation integrated
development environment.
.FPO Directive
--------------
The .FPO directive controls the emission of debug records to the
.debug$F segment or section. This directive was originally included
with MASM386 and is not supported by MASM 6.11. If you are using
both MASM 6.11 and MASM386, the following allows you to continue to
implement the .FPO directive:
IF @version LT 600
.FPO
ENDIF
INVOKE Command
--------------
The MASM 6.x INVOKE command does not support transferring control
between 16-bit and 32-bit code segments. When the assembler
encounters an INVOKE command in a 16-bit segment, it assumes
that the procedure being invoked is also in a 16-bit segment; if
the assembler encounters an INVOKE in a 32-bit segment, it assumes
that the invoked procedure is also in a 32-bit segment.
To avoid this problem, push the necessary parameters on the stack
and make the appropriate call instead of using INVOKE.
LINK and System Resources
------------------------
You may encounter the following error message when running LINK on
Windows 3.1:
System resource exhausted. Abort, Retry, Fail?
This may occur because LINK opens a large number of files, and the
buffer for SHARE may have been exceeded. To fix this problem, edit
your AUTOEXEC.BAT, setting the following values for SHARE:
/L:500 /F:4096
MOUSE.COM
---------
Microsoft Mouse Driver (MOUSE.COM) Version 8.20a is included with
MASM 6.11. If you have a later version of the Microsoft Mouse
installed on your system, it is recommended you use it instead of
the Mouse Driver included with MASM 6.11.
MS-DOS and Windows NT File Compatibility
----------------------------------------
Files installed on the Microsoft Windows NT File System (NTFS) are
accessible only on Microsoft Windows NT. Files installed on the
MS-DOS File System (FAT) are accessible on MS-DOS, Microsoft Windows,
or Microsoft Windows NT.
Multi-File Assembly with MASM.EXE
---------------------------------
When assembling multiple files with MASM.EXE, you must terminate the
command-line with a semi-colon or a comma (for example, MASM *.asm;).
Failure to do this may cause the program to appear to hang if you are
running Microsoft NT. If this does occur, you can terminate the program
with Ctrl+C.
NMAKE and NMAKER
----------------
MASM 6.11 includes two versions of the NMAKE project management
utility. NMAKER.EXE is a real-mode version of the utility.
NMAKE.EXE is a driver program which first loads the MS-DOS extender
DOSXNT into memory, and then runs NMAKER.EXE. Using the NMAKE.EXE
driver will result in faster build times. Some development tools
from other manufacturers may be incompatible with NMAKE.EXE. If you
encounter incompatibilities, use NMAKER.EXE instead.
Response Files
--------------
Information on response files is not included in the MASM 6.1 manuals;
however, this information can be found in "ML Command Line Options"
in Online help.
SAMPLES.TXT and NTSAMPLE.TXT
----------------------------
SAMPLES.TXT contains information about the MASM samples for
MS-DOS/Windows; NTSAMPLE.TXT contains information about the
samples given for MASM for Windows NT. Both files include
information about additional tools you may need to build some
of the samples. If you choose to install the sample code during the
setup process, both SAMPLES.TXT and NTSAMPLE.TXT are included.
SAMPLES.TXT can be found in the \MASM611\SAMPLES subdirectory;
NTSAMPLE.TXT can be found in the \MASM611\SAMPLES\NTSAMPLE
subdirectory.
Using Control-C to Halt Operation of MASM
-----------------------------------------
MS-DOS applications running under DPMI, such as ML.EXE, may not
respond immediately to pressing Control-C. If you press Control-C,
and ^C appears on the screen but you are not returned to MS-DOS,
press the Enter key.
Using MASM 6.x Structures
-------------------------
MASM 6.x supports a more powerful syntax for structure definition
and usage than previous versions of MASM. This more powerful
syntax is enabled by default. To use the older syntax, issue
the OPTION OLDSTRUCTS directive (see Appendix A of the MASM
Programmer's Guide for more information).
Note: use of nested structures requires the new MASM 6.x syntax.
If you use nested structures, the OPTION OLDSTRUCTS directive will
be ignored for the structure which is nested.
Visual C++ 1.0/Fortran PowerStation 1.0 Compatibility
-----------------------------------------------------
There are specific steps you must take to use MASM 6.11 with
Microsoft Visual C++ 1.0 or Microsoft Fortran PowerStation 1.0.
If you wish to do mixed language programming with these products, it
is recommended that:
- You install Visual C++/Fortran PowerStation and MASM 6.11 in
separate sub-directories.
- You place \MSVC\BIN or \F32\BIN (your Visual C++ or Fortran
PowerStation sub-directory) first on your path statement before
\MASM611\BIN (your MASM 6.11 sub-directory).
- You use NMAKE.EXE from MASM 6.11. You can do this using various
methods, such as moving or renaming NMAKE.EXE installed in \MSVC
or \F32 thus causing the system to continue searching your path
and use the NMAKE.EXE in \MASM611.
Optionally, for MASM 6.11/Visual C++ mixed programming, you may
use NMAKER.EXE which is installed with both products.
When using the LINK utility included with Visual C++ 1.0, you may
encounter one or both of the following warnings:
LINK : warning L4017: /r : unrecognized option name; option
ignored
CVPACK : warning CK4007 : unrecognized option /x; option
ignored
These warnings do not affect the resulting program and should be
ignored.
Working with MASM 5.1 Code
--------------------------
MASM 6.x offers major advances over previous versions of MASM.
Some of these improvements require changes that make MASM 5.1
source code incompatible with MASM 6.x. To provide compatibility
with code written for MASM 5.1, MASM 6.x allows you to access
MASM 5.1 compatibility code in three ways:
- By using the conversion driver MASM.EXE. MASM.EXE converts
your existing command-line options to the new syntax, adds
the compatibility option /Zm, and invokes ML.EXE.
- By using ML.EXE with the /Zm option. You also need to
convert command-line options to the new syntax.
- By placing the statement OPTION M510 at the beginning of
each file. You also need to convert command-line options
to the new syntax.
In most cases, using the /Zm option or OPTION M510 will be the best
solution for assembling existing code. If you prefer to modify your
code so it can be assembled without /Zm or OPTION M510, do the
following:
1. Add the appropriate OPTION directives to your code.
- Always add the following:
OPTION OLDSTRUCTS ; Supports old-style structures
OPTION OLDMACROS ; Supports old-style macros
OPTION DOTNAME ; Supports naming identifiers with
; a leading dot [.]
- If your code does not specify the .386 or .386P directive, add
the following:
OPTION EXPR16 ; Use 16-bit precision in expressions
- If your code does not contain a .MODEL directive, add the
following:
OPTION OFFSET:SEGMENT ; Specifies that the OFFSET operator
; defaults to segment-relative rather
; than group-relative
- If your code does not contain a .MODEL directive or if the
.MODEL directive does not specify a language, add the following:
OPTION NOSCOPED ; Makes code labels global rather than
; local to the procedure in which they
; appear
OPTION PROC:PRIVATE ; Makes code labels defined with PROC
; local unless specified otherwise
2. Once your code assembles with the OPTION directives, remove each
OPTION directive, one at a time, and reassemble the code after you
remove each one.
Usually, it is best to remove the OPTION directives in the
opposite order in which you added them. In some cases, you may
decide that you prefer the MASM 5.x compatibility behavior
instead of the new MASM 6.x behavior. When this is true, do not
remove the corresponding OPTION statement from your code.
For more information on assembling MASM 5.1 code, see Appendix A
of the MASM Programmer's Guide.
Working With Microsoft BASIC Far Strings
---------------------------------------------
The BASIC runtime function StringAssign does not correctly handle
strings of zero length. Instead of calling StringAssign to convert
a zero-length string, simply return a near pointer to a doubleword
with the value 0.
======================< Part 4: Known Assembler Bugs >====================
Exiting from MS-DOS Critical Errors
--------------------------------------------------
MS-DOS critical errors, such as attempting to assemble a file on
a drive which does not exist or is empty, produce the "Abort, Retry
or Fail?" error message. Selecting "Abort" when running MASM in
MS-DOS may cause memory to be corrupted. This problem does not
occur when running MASM in Windows. To avoid this problem, select
"Retry" or "Fail", as appropriate.
Expression Order in High-Level Conditionals
--------------------------------------------------
Comparisons in high-level conditionals cannot begin with a literal.
For instance, this comparison causes an error:
.IF 1 == AX
but this works properly:
.IF AX == 1
Hexadecimal Constants
---------------------
In some instances, ML might not generate the appropriate error
message if it encounters a hexadecimal constant that does not have
an appending "h". The following will help to ensure that hexadecimal
constants are properly represented:
- Make sure that all hexadecimal constants have an appending "h".
- Begin all hexadecimal constants with the numeral 0. This ensures
that the compiler will generate the appropriate error message
if it encounters a hexadecimal constant that does not end in "h".
Initializing Nested Structures
--------------------------------------------------
If one structure is nested within another, the inner structure's
initializer list must either be empty or include a comma between
every field. For example, the structure INFO declared on page 123
of the Programmer's Guide contains a structure of type DISKDRIVES,
which in turn contains three BYTE fields. An object of type INFO
could be initialized as:
Info1 INFO { , , , , { }} ; Inner initializer list is blank
or as:
Info1 INFO { , , , , {1, 2, }} ; Commas for all three fields
but not as:
Info1 INFO { , , , , {1, 2 }} ; Error: missing last comma
Intersegment Near Jumps in Flat Model
-------------------------------------
Intersegment near jumps do not work across files (externs) in flat
model. When programming in flat mode, make sure that all intersegment
near jumps occur within the same file.
Span-Dependent Expressions used in Macros
--------------------------------------------------
MASM 6.1x evaluates macro expressions only on the first pass of
assembly, but code and data are reevaluated on subsequent passes.
Because of this, macro expressions which depend on the span between
two addresses may not evaluate correctly. For instance, the
following code will not evaluate correctly:
Label1:
JMP Label2
Label2:
REPEAT Label2 - Label1 ; Evaluates incorrectly
INC AX
ENDM
View the listing file to determine if a questionable macro expression
was evaluated as desired.
Span-Dependent Equates in Macros and EXTERNDEF ABS
---------------------------------------------------
The ABS operator causes an identifier to be exported as a relocatable
unsized constant (see Programmer's Guide page 220). If ABS is used
with EXTERNDEF within a macro, and the constant being exported
depends on the difference between two addresses, the constant may not
be exported correctly. In some cases, the listing file will show the
correct value, but the value in the resulting .obj will be incorrect.
For instance, the following code will not evaluate correctly:
EXTERNDEF TableSize:ABS ; Will not be exported correctly
MAKETABLE MACRO
Table1 LABEL BYTE
DB 0, 1, 2
TableSize EQU $-Table1
ENDM
SEG1 SEGMENT
MAKETABLE
SEG1 ENDS
To avoid this problem, either use the 'PUBLIC' directive in place of
'EXTERNDEF', or put a label before the equate, within the macro.
Span-Dependent Text Equates
--------------------------------------------------
The TEXTEQU operator is evaluated on the first assembly pass. If
TEXTEQU is used with an expression that depends on the difference
between two addresses, the resulting constant may be incorrect.
For instance, the following code will not evaluate correctly:
Label1:
JMP Label2
Label2:
WrongNum TEXTEQU %Label2-Label1 ; WrongNum will be incorrect
STRUCT and RECORD Initialization
--------------------------------
If a STRUCT containing a UNION is initialized incorrectly, it is
possible that the compiler might not generate an appropriate error.
If the UNION contains a RECORD, the STRUCT is initialized to the
default value for the original UNION.
Using The /link /nologo Command Line Options
---------------------------------------------------------
The /link command line option for ML causes all following parameters
to be passed to the linker. If the /nologo command line option
is passed to the linker, the linker may parse other parameters
incorrectly. To avoid this problem, use the /nologo command line
switch for ML rather than passing it to the linker. For instance,
replace:
ML hello.asm /link /nologo MYLIB.LIB
with:
ML /nologo hello.asm /link MYLIB.LIB
Alternately, you may use the NMAKE utility to automate building
your project.
