TURBO ASSEMBLER 3.2
MANUAL REFERENCE & CORRECTIONS
==============================
CONTENTS:
Turbo Assembler 3.2: 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 white space 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 made PUBLIC
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 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.
Q. Some of my code that assembles with previous versions of Turbo
Assembler now report errors on lines that use text equate
string substitutions. What should I do?
A. Turbo Assembler 3.2 now provides greater MASM compatibility for
text equate substitutions. Whenever a line requires the expansion
of a text macro, use the % operator at the beginning of the line
to specifically indicate that the text macros should be expanded
before the line is parsed. In previous versions of Turbo
Assembler, some instances of text macros (particularly where text
macros had the same names as assembly language keywords) would not
be expanded.
For example, this situation could occur when you define a model on
the command line. You could assemble
.MODEL M
.CODE
NOP
END
with the following command line:
TASM /dM=SMALL A.ASM
Since Turbo Assembler now requires you to place the % operator at
the beginning of the line containing the text equate substitution,
this program would change to:
% .MODEL M
.CODE
NOP
END
If you omit the %, you might receive an "Invalid Model Type"
error.
Q. Some of my code that assembles with previous versions of Turbo
Assembler now report warnings on lines with segment overrides.
What should I do?
A. Turbo Assembler 3.2 now handles segment overrides in a more
consistent manner. All segment overrides in MASM mode programs
must occur outside the [] of a memory expression. For example,
this line that previous versions of TASM would accept,
MOV AX,[ES:BX]
will now generate a warning:
*Warning* segment.ASM(3) ":" operator ignored
Also, the segment override will not be generated.
To fix this warning, and to cause the expected segment override, it is
important to move the ES: outside of the memory [], like this:
MOV AX,ES:[BX]
