
			       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.
