README.DOC File

             Release Notes for the Microsoft(R) Macro Assembler
                Professional Development System, Version 6.0

                  (C) Copyright Microsoft Corporation, 1991
     This document contains release notes for version 6.0 of the
     Microsoft Macro Assembler Professional Development System for
     MS-DOS(R) and the Microsoft Operating System/2 (MS(R) OS/2). The
     information in this document and in the Microsoft Advisor (online
     help) is more up-to-date than that in the manuals.
     Microsoft improves its languages documentation at the time of
     reprinting, so some of the information in this file may already be
     included in your manuals.

================================< Contents >================================

     This file has 7 parts:
               Part     Contents
               ----     --------
               1        Information for MASM 5.1 programmers

               2        Notes on "Installing and Using"

               3        Notes on "MASM 6.0 Reference"

               4        Notes on "MASM 6.0 Programmer's Guide"

               5        Using the DOS-Extended assembler

               6        Changes to CMACROS.INC

               7        Known assembler bugs

===============< Part 1: Information for MASM 5.1 programmers >=============

     "Quick Start" booklet

     If you have programs that assemble with previous versions of MASM,
     this booklet will help you to use MASM 6.0.

=================< Part 2: Notes on "Installing and Using" >================

     Installation Program Notes

        - Use "SETUP /M" if you are using a monochrome display adapter
          as your primary display.

        - Under OS/2, if you are already running QuickHelp as a keyboard
          monitor, disable it before running SETUP so that it can copy
          new versions of QuickHelp and MSHELP.DLL to your hard disk.

==================< Part 3: Notes on "MASM 6.0 Reference" >=================

     Page    Note
     ----    ----

     16      MASM /D Option
             The /D Option is translated as follows:

             /D        Creates a Pass 1 listing. Translated to /Fl /Sf.

     17      ML /VM Option
             /VM       Enables virtual memory under MS-DOS.

     33      EXITM Directive
             The EXITM directive takes an optional textitem, not an

     152     XCHG Instruction
             The second example line should be as follows:

             xchg  dl, dh

==============< Part 4: Notes on "MASM 6.0 Programmer's Guide" >============

     Reserved Words

     Add this paragraph to the description of reserved words in Section
     1.21, "Reserved Words," and Appendix D, "MASM Reserved Words":

     With the /Zm command-line option or OPTION M510, keywords and
     instructions that are not available in the current CPU mode (such as
     ENTER under .8086) are not treated as keywords. The USE32, FLAT, FAR32,
     and NEAR32 segment types and the 80386/486 registers are not keywords
     with processor selection directives less than .386.

     ALIGN, EVEN, and ORG in Structures and Unions

     Add this paragraph to Section 5.2, "Structures and Unions."

     The ALIGN, EVEN, and ORG directives can be used during structure
     definition to modify how offsets of elements are defined. The EVEN
     and ALIGN directives will round the current field offset up to the
     specified align value by inserting padding bytes into the skipped
     space. The ORG directive may be used to change the current field
     offset to a new value, either positive or negative. If the ORG
     directive is used in a structure definition, you cannot create an
     instance of the structure.

     Nested Structure Example

     Change this line in the first example of Section 5.2.2, "Defining 
     Structure and Union Variables."

           ITYPE     UNION

     should be:

           UNION     ITYPE


     The table in Section 9.7.2, "Testing for Argument Type and 
     Environment" should be as follows:

     Option     Description
     ------     -----------
     ASSUMES    Saves segment register information
     LISTING    Saves listing and CREF information
     CPU        Saves current CPU and processor
     RADIX      Saves current default radix
     ALL        All of the above

     New Anonymous Bitfield Syntax
     Add these paragraphs to Section 16.3.5, "Bit Fields."

     H2INC translates anonymous bitfields by padding with a tag
     corresponding to the bit position.

     For example,

     struct s
        int :8;
        int j:8;


     s      RECORD  j@s:8,

     Basic/MASM Far Externs

     Add these paragraphs to Section 20.3.3, "The Basic/MASM Interface."

     When interfacing with Basic, all EXTERNs that are far must be
     declared outside of a code or data segment.

     This is incorrect:

     .MODEL     medium
     EXTERN     StringAddress:FAR

     This is correct:

     .MODEL     medium
     EXTERN     StringAddress:FAR

     New Command-line Options

     Add these paragraphs to Appendix C, "Generating and Reading Assembly

     With the PAGE directive, the default page length is 0 (infinite), and
     the default page width is 0 (infinite). The allowable range of values
     is 0 and 60-255 for page width, 0 and 10-255 for page length.

     With the /Sf option, a first-pass listing will be generated even if
     a fatal error occurs. The symbol table will be appended onto the end
     of the listing file unless you give the /Sn option.

     The first-pass listing is controlled by the same set of commands that
     are used with the final listing.

     Additional Error Messages

     Add these new or changed error messages to Appendix F, "Error

     MASM fatal error A1006

     invalid command-line option: 'option'

     ML did not recognize the given parameter as an option.

     This error is generally caused when there is a syntax error on the
     command line. It can also be generated by trying to assemble multiple
     assembly language files on the MLX driver command line.

     MASM fatal error A1017

     out of near memory

     There was insufficient memory to assemble the program.

     One of the following may be a solution:

        - If you are using the NMAKE utility, try using NMK or
          assembling outside of NMAKE.

        - in PWB, try exiting and assembling using ML.

        - In OS/2, try increasing the swap space.

        - In DOS, remove terminate-and-stay-resident (TSR) software.

        - If you have extended memory available, use the MLX.EXE driver.

        - Change CONFIG.SYS to specify a lower number of buffers (the
          BUFFERS= command) and fewer drives (the LASTDRIVE= command).

        - Eliminate unnecessary INCLUDE directives.

     MASM fatal error A1019

     invocation failed : retry command line with /VM option

     ML tried to restart itself with the /VM option but failed.

     Enter the ML command line again, but add the /VM virtual-memory
     option explicitly.

     MLX fatal error A1800

     processor not 80286 or above

     You can only run MLX.EXE on an 80286 or above processor.

     Use ML.EXE if you do not have an 80286 or 80386/486 processor.

     MLX fatal error A1801

     processor in protected or virtual 8086 mode

     The MLX driver cannot run from XMS memory when in protected or
     virtual 8086 mode.

     MLX fatal error A1802

     DPMI, VCPI, or XMS driver not installed

     The MLX driver cannot find a compatible driver in memory.

     You must have a DPMI, VCPI, or XMS driver, such as HIMEM.SYS,
     installed before running MLX.EXE.

     MLX fatal error A1803

     unexpected initialization error

     The MLX driver was unable to initialize the memory manager.

     Make sure that you have a compatible DPMI, VCPI, or XMS driver
     installed. HIMEM.SYS is a compatible XMS driver and is included in
     this package.

     MLX fatal error A1804

     not enough near memory to load MLX.EXE

     There was insufficient memory to start the DOS-extended assembler.

     One of the following may be a solution:

        - If you are using the NMAKE utility, try using NMK or
          assembling outside of NMAKE.

        - Remove terminate-and-stay-resident (TSR) software.

        - Change CONFIG.SYS to specify a lower number of buffers (the
          BUFFERS= command) and fewer drives (the LASTDRIVE= command).

     MLX fatal error A1805

     unable to run under Windows in standard mode

     You can only run MLX.EXE in a Windows DOS box when running real or
     386 enhanced mode.

     MLX fatal error A1806

     insufficient extended memory to load ML.EXE

     There is not enough extended memory available to load the assembler
     into high memory.

     Change your configuration to give more memory to the DOS extender.
     This may involve reducing the size of a RAM disk or cache.

     MLX fatal error A1807

     disk I/O error while loading program

     The assembler encountered an error when trying to load ML into high

     One of the following may be a cause:

        - The disk has a bad sector.

        - The file-access attribute is set to prevent reading.

        - The drive is not ready.

     MLX fatal error A1808

     out of space in GDT

     The MLX driver could not add enough entries to the Global
     Descriptor Table (GDT).

     You may be able to overcome this problem by rebooting your system
     and running MLX.EXE before starting other programs.

     MLX fatal error A1809

     bad environment table

     There was an invalid environment table passed to MLX.EXE.

     The calling program passed a bad environment table. This error can
     be caused by a corrupt version of COMMAND.COM.

     MLX fatal error A1810

     cannot load ML.EXE

     The ML driver could not be found in the current path.

     Make sure that the DOS version of ML.EXE was copied from the
     distribution disks and is in the current path.

     MLX fatal error A1811

     ML.EXE not protected-mode compatible

     An obsolete version of ML.EXE was found in the current path.

     Make sure that the DOS version of ML.EXE was copied from the
     distribution disks and is in the current path.

     MLX fatal error A1850

     unrecoverable fault

     The MLX driver called ML.EXE, which generated a system error.

     Note the circumstances of the error and notify Microsoft
     Corporation by following the instructions in the Microsoft Product
     Assistance Request form at the back of one of your manuals.

     MASM error A2007

     non-benign record redefinition

     A RECORD definition conflicted with a previous definition.

     One of the following occurred:

        - There were different numbers of fields.

        - There were different numbers of bits in a field.

        - There was a different label.

        - There were different initializers.

     MASM error A2202

     illegal use of segment register

     You cannot use segment overrides for the FS or GS segment registers
     when generating floating-point emulation instructions with the /FPi
     command-line option or OPTION EMULATOR.

     MASM error A2203

     cannot declare scoped code label as PUBLIC

     A code label defined with the "label:" syntax was declared PUBLIC.

     Use the "label::" syntax, the LABEL directive, or OPTION NOSCOPED
     to eliminate this error.

     MASM error A2204

     .MSFLOAT directive is obsolete : ignored

     The Microsoft Binary Format is no longer supported.

     You should convert your code to the IEEE numeric standard, which is
     used in the 80x87-series coprocessors.

     MASM error A2205

     ESC instruction is obsolete : ignored

     The ESC (Escape) instruction is no longer supported. All numeric
     coprocessor instructions are now supported directly by the assembler.

     MASM warning A4005

     unknown default prologue argument

     An unknown argument was passed to the default prologue.

     The default prologue understands only the FORCEFRAME and LOADDS

     MASM warning A4013

     line number information for segment without class 'CODE'

     There were instructions in a segment that did not have a class
     name that ends with "CODE". The assembler did not generate
     CodeView information for these instructions.

     CodeView cannot process modules with code in segments with
     class names that do not end with "CODE".

     MASM warning A4014

     instructions and initialized data not supported in AT segments

     An instruction or initialized data was found in a segment defined
     with the AT attribute. The code or data will not be loaded at run

     Data in AT segments must be declared with the ? initializer.

     MASM warning A6004

     procedure argument or local not referenced

     You passed a procedure argument or created a variable with the LOCAL
     directive that was not used in the procedure body.

     Unnecessary parameters and locals waste code and stack space.

     MASM warning A6005

     IF condition may be pass-dependent

     Under the /Zm command-line option or the OPTION M510 directive,
     the value of an IF condition changed between passes.

     This error message may indicate that the code is pass-dependent and
     must be rewritten.

     H2INC fatal error HI1801

     incomplete model specification

     Only part of a custom memory-model specification was specified on
     the command line.

     When you specify a custom memory model with the /A command-line
     option, you must specify code pointer distance, data pointer distance,
     and DS register setup. This error is equivalent to the D2013 error
     message for CL.

=================< Part 5: Using the DOS-extended assembler >===============

     MLX: The DOS-Extended Assembler

     There is a new DOS-extended driver for ML called MLX. MLX loads
     ML.EXE into high memory so that the assembler takes up very little
     space in the first 640K of memory.

     MLX uses extended memory to run ML in protected mode. If you have
     multiple extended memory drivers available, MLX will select the
     driver to use in this order:

       - DPMI
       - VCPI
       - XMS

     The HIMEM.SYS XMS driver is included in the MASM 6.0 package and
     is automatically copied by setup into the real-mode executables
     directory as MLX.EXE. To use HIMEM.SYS, put the following line
     into your CONFIG.SYS file:

       DEVICE = <path>HIMEM.SYS

     Where <path> is the path to the location of HIMEM.SYS.

     Use MLX only if running ML with the /VM virtual-memory option fails
     due to an out of memory error. Because it runs in real mode, ML
     with the /VM command-line option can run significantly faster than

     MLX Requirements

     MLX requires an active DPMI, VCPI or XMS driver and at least 384K
     of available extended memory to operate.

     Differences between ML and MLX

     The MLX DOS-extended driver can only assemble one source file at
     a time. You must split multiple-file assemblies into several
     invocations of MLX.

     If you want to use MLX from the PWB command line, you must manually
     change your makefile to reflect the name of the MLX driver. Change
     the line:

       ASM = ML


       ASM = MLX

======================< Part 6: Changes to CMACROS.INC >====================

     Using CMACROS.INC

     There is a new, MASM 6.0-compatible version of CMACROS.INC included
     with the assembler. If you work with the Windows 3.0 Software
     Development Kit, or the C 6.0 or FORTRAN 5.0 startup code, use the 
     new version of CMACROS.INC.

     C and FORTRAN Startup Sources

     To build the C or FORTRAN start-up sources, change the ASMFLAGS line
     of MAKEFILE from

     ASMFLAGS= -Mx -Dmem_$(MODEL) -I$(INC)



=====================< Part 7: Known assembler bugs >===================

     Ambiguous Radix Characters

     The assembler accepts numeric characters outside the range of the
     current radix.  These characters are given their appropriate
     values but are handled under the current radix.  For example,

     .RADIX 10
     mov    ax, 1F
     mov    bx, 1Fh

     loads ax with 25 (10 from the tens digit and 15 from the ones).
     The bx register is loaded properly.