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                        TURBO ASSEMBLER 3.1
                      MANUAL REFERENCE & CORRECTIONS

CONTENTS:
    Turbo Assembler 3.1: Answers to Common Questions  

  The following are tips, tricks, and hints you may find useful
  when using Turbo Assembler.

 Q. When should I use the different assembly modes TASM provides
    for existing assembly programs?
 A. Mode                   Conditions for Use
    -------------------------------------------------------------
    Normal(MASM)         - Program assembles under MASM 4.00 or
                           MASM 5.00.
    Quirks               - Program assembles under MASM 4.00 or
                           MASM 5.00, but won't assemble under
                           TASM without MASM51 or QUIRKS.
    Masm51               - Program requires MASM 5.1 for assembly.
    Masm51 and Quirks    - Program requires MASM 5.1 for
                           assembly, but will not assemble
                           under TASM with only the MASM51
                           switch set.

 Q. Do I have to use MASM51 to assemble files written for MASM
    5.1?
 A. Most files will assemble even without using the MASM51
    directive. However if your assembly code utilizes features
    only found in MASM 5.1, you will need to use the MASM51 mode.
    Check the table in the next Q&A to see which features of MASM51
    emulation are enabled by combinations of MASM51 and QUIRKS
    modes.

 Q. What items are controlled by the QUIRKS and MASM51 modes?
 A. The following table lists what the various combinations of
    QUIRKS and MASM51 modes do:

    Mode                   Operations
    -------------------------------------------------------------
    Quirks               - Allows FAR jumps to be generated as
                           NEAR or SHORT if CS assumes agree.
                         - Allows all instruction sizes to be
                           determined in a binary operation solely
                           by a register, if present.
                         - Destroys OFFSET, segment override,
                           etc., information on '=' or numeric 'EQU'
                           assignments.
                         - Forces EQU assignments to expressions
                           that contain "PTR" or ":" to be text.

    Masm51               - Instr, Catstr, Substr, Sizestr, and
                           "\" line continuation are all enabled.
                         - EQU's to keywords are made TEXT
                           instead of ALIASes.
                         - Leading whitespace is not discarded
                           on %textmacro in macro arguments.

    Masm51 and Quirks    - Everything listed under QUIRKS above.
                         - Everything listed under MASM51 above.
                         - @@, @F, and @B local labels are
                           enabled.
                         - Procedure names are PUBLIC'ed
                           automatically in extended MODELs.
                         - Near labels in PROCs are redefinable
                           in other PROCs.
                         - "::" operator is enabled to define
                           symbols that can be reached outside of
                           current proc.

    Masm51 and Ideal     - Ideal mode syntax and the Masm51 text
                           macro directives are supported, i.e.,
                           Instr, Catstr, Substr, and Sizestr.

  Q. When should I use the DOSSEG or .STACK directives?
  A. When you're developing Turbo Assembler modules to link with
     high-level languages like Turbo C++ and Turbo Pascal, you
     don't need the DOSSEG or .STACK directives because these
     compilers will handle segment-ordering and stack setup.
     These directives define segment names and order that might
     conflict with those used by the high-level language. You
     only need, however, to define these once in any module of a
     standalone assembler program. DOSSEG is only needed if you
     want your segments to be ordered using Microsoft's
     conventions. You can define your own segment-ordering by
     ensuring that your segments are encountered by TLINK in the
     order that you wish. See the TLINK section of the manual for
     a full description of how this works.

  Q. What options should I use when I use Turbo Assembler to
     assemble the files that came with the Microsoft C Compiler?
  A. When assembling the assembly language modules provided with the
     Microsoft compilers, make sure to use the MASM51 and QUIRKS
     modes. For example,

       tasm /jmasm51 /jquirks filename

  Q. How do I create a .COM file?
  A. Your assembler source should be assembled in the tiny model
     (.MODEL TINY) and should include an ORG 100h following the
     opening of the code segment, as shown below:

                .MODEL  TINY
                .CODE
                ORG     100h
        start:
                ....          ; body of program
        END     start         ; defines the entry point as start

     Don't include a .STACK directive in a program designed to be
     a .COM.

     TLINK will create a .COM file instead of an .EXE file if the /t
     option is specified. For example,

        tlink /t SHOW87

     will create SHOW87.COM instead of SHOW87.EXE.

     There are certain limitations in converting an .EXE file to a
     .COM file. These limitations are documented in the IBM Disk
     Operating System manual under EXE2BIN.

  Q. How do I assemble multiple files with Turbo Assembler?
  A. Turbo Assembler will assemble multiple files using wildcard
     characters or separating them by the plus (+) character.
     As an example, the following command line

       tasm filt + o*

     would assemble the file FILT.ASM, as well as all the .ASM
     files beginning with the letter 'o'.

  Q. How can I assemble multiple files if they don't all use the
     same command-line options?
  A. Turbo Assembler uses the semicolon (;) character as a
     command-line separator so that you can actually have
     multiple assembler command lines on a single DOS command
     line. As an example, the following command line

       tasm /zi filt; o*

     would assemble the file FILT.ASM with debug information
     turned on, then assemble all the .ASM files beginning with
     the letter 'o' without debug information.

  Q. Microsoft's Macro Assembler allows me to define environment
     variables so I don't have to enter them on every command
     line. Can I do this with Turbo Assembler as well?
  A. No, but Turbo Assembler provides an even more flexible way
     to eliminate typing in command-line options every time.
     Whenever you run Turbo Assembler, it looks in the current
     directory, then in the directory from which it was started
     (DOS 3.x and greater) for a special file called TASM.CFG.
     This file can contain anything that the command line
     contains. This file is processed first and then the command
     line so that the command-line options take priority over
     those found in the TASM.CFG configuration file. If, for
     instance, your command-line options are always

       /t /ml /zi /jJUMPS /jLOCALS

     you could create TASM.CFG file containing these lines

       /t
       /ml
       /zi
       /jJUMPS
       /jLOCALS

     Now, every time you run Turbo Assembler, those will be the
     default options. This means that, if you need to, you can
     have separate TASM.CFG files for each of your projects. If
     you have multiple projects residing in a single subdirectory,
     then you could create a separate configuration file for each
     and use them as Turbo Assembler indirect command files.

  Q. What are Turbo Assembler indirect command files?
  A. These are files that contain partial or complete Turbo
     Assembler command lines and are preceded with an at-sign (@)
     on the command line. For example, if you have a file named
     "FILE.CMD" that contains the following,

       /t
       /ml
       /zi
       /jJUMPS
       /jLOCALS
       file1 +
       file2 +
       file3 +
       file4

     then you could use the command line

       tasm @FILE.CMD

     instead of the command line

       tasm /t /ml /zi /jJUMPS /jLOCALS file1+file2+file3+file4

     Note that the at-sign (@) is not actually part of the file's
     name. In fact, if you name a file with an at-sign at the
     beginning, Turbo Assembler will treat it as an indirect
     command file.

  Q. I am linking my own assembly language functions with Turbo C.
     Why does the linker report that all of my functions are
     undefined?
  A. Make sure you've put an underbar character (_) in front
     of all assembly language function names to be called
     by Turbo C. If you use simplified segmentation and include
     the C language specifier on the .MODEL directive, Turbo
     Assembler will pre-append the underbar automatically for you.
     Your assembly language program should be assembled with Case
     Sensitivity (/ML or /MX). 

  Q. Can I use the backslash (\) instead of the slash (/) as a
     option specifier?
  A. NO! Turbo Assembler (and MASM) will treat that as a file
     that resides in the root directory of the default drive.
     Since both assemblers treat the space character ( ) as a
     comma (,) this could result in the loss of files. If you
     accidentally gave this command line,

      tasm \zi prid&joy.asm

     Turbo Assembler (and MASM) would treat this command line as
     instructions to assemble a file called ZI.ASM that can be
     found in the root directory and create an output file in the
     current directory called PRID&JOY.ASM. (Note that the
     assemblers think the default extension for the object file
     of .OBJ has been explicitly overridden to .ASM.) The file
     PRID&JOY.ASM will either be overwritten with the object file
     or deleted if the file \ZI.ASM can't be found and success-
     fully assembled. In either case, the original contents of
     PRID&JOY.ASM are now lost.

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