x86 Assembly Language FAQ - Borland TASM 
Author Message
 x86 Assembly Language FAQ - Borland TASM

Archive-Name: assembly-language/x86/borland
Posting-Frequency: monthly (21st of every month)
Last-modified: 1997/02/22


Subject: 1. Introduction and Intent

This is the x86 Assembly Language FAQ for the comp.lang.asm.x86 and
alt.lang.asm newsgroups.  This FAQ is posted monthly on or about the 21st
of the month on both newsgroups and news.answers, alt.answers and
comp.answers.  It also is archived at the normal FAQ archival sites and the
SimTel mirror sites in the msdos/info directory.  Lastly, the current
version is available from my web page as:
    As text files:
        http://www.*-*-*.com/ ~raymoon/faq/asmfaq.zip
    As html documents:
        http://www.*-*-*.com/ ~raymoon/faq/asmfaqh.zip
Currently, this FAQ is broken into six sections.  The following are the
section filenames and the scope of each section of the FAQ.

assembly-language/x86/general/part1 - This is the basic portion of the FAQ
    that contains information of interest to all assembly language
    programmers.  In general, the information contained in this portion of
    the FAQ is not specific to any particular assembler.

assembly-language/x86/general/part2 - This is a continuation of the above

assembly-language/x86/general/part3 - This is a continuation of the above

assembly-language/x86/microsoft - This portion of the FAQ contains
    information specific for the Microsoft MASM.

assembly-language/x86/borland - This portion of the FAQ contains
    information specific for the Borland TASM.

assembly-language/x86/a86 - This portion of the FAQ contains information
    specific for the Shareware A86 Assembler and D86 De{*filter*}.

The scope and content of this FAQ is to go beyond just answering the
frequently asked questions.  I am including pointers to assembly language
treasure troves that are hidden out on the internet.  I believe that this
will enhance the FAQ's value not only to the novices but also to the old

For the ease of determining what has changed since the last FAQ, the Table
of Contents will have "REVISED" at the end of the subject line for all
revised subjects.  If more than one FAQ revision has been missed, the "Last
Changed:" entry at the end of each subject can be used to determine which
subjects have been revised during the intervening time frame.

The information in this FAQ is free for all to use as long as you
acknowledge the source.  This FAQ can be reproduced in part or in its
entirety as long as the copyright is included.  This FAQ can be made
available on public servers, like ftp, gopher or WWW servers.  Please do
not modify the file, such as converting it into some other format, without
prior permission of the author.

All references to files and locations are in Uniform Resource Locators
(URLs) format.  Some web browser will be able to use these URLs directly as
hot links.  If the format is not clear to you, get RFC 1738.  It is
available from:   ftp://ds.internic.net/rfc/rfc1738.txt

Suggestions for changes and comments are always welcome.  They can be
posted to either newsgroup or e-mailed directly to the me.

Copyright 1997 - Raymond Moon
Last Changed: 6 Jan 97


Subject: 2. Table of Contents

1. Introduction And Intent
2. Table Of Contents                                            REVISED
3. TASM Ideal Mode
4. Borland TASM Information
5. Borland tools/Windows 95 Interworking Patches Available
6. Borland TASM List Server                                     REVISED
7. FREELIB, Version 3.0


Subject: 3. TASM Ideal Mode


TASM, Borland's assembler, supports an alternative to MASM emulation.  This
is known as Ideal mode and provides several advantages over MASM.  The key
(questionable) disadvantage, of course, is that MASM style assemblers
cannot assemble Ideal mode programs.


Square brackets are used consistently to refer to memory contents.  Notice
that size qualifiers are not necessary when TASM has enough information by
context to figure out the data size involved.  Here are some examples
without segment details:

   ByteVal db ?          ; "ByteVal" is name of byte variable

   mov ax, bx            ; OK:  Move value of BX to AX

   mov ax, [bx]          ; OK:  Move word at address BX to AX.  Size of
                         ; destination is used to generate proper object
                         ; code

   mov ax, [word bx]     ; OK:  Same as above with unnecessary size
                         ; qualifier

   mov ax, [word ptr bx]
                         ; OK:  Same as above with unnecessary size
                         ; qualifier and redundant pointer prefix

   mov al, [bx]          ; OK:  Move byte at address BX to AL.  Size of
                         ; destination is used to generate proper object
                         ; code

   mov [bx], al          ; OK:  Move AL to location BX

   mov ByteVal, al       ; Warning: "ByteVal" needs brackets

   mov [ByteVal], al     ; OK:  Move AL to memory location named "ByteVal"

   mov [ByteVal], ax     ; Error: unmatched operands

   mov al, [bx + 2]      ; OK:  Move byte from memory location BX + 2 to
                         ; AL

   mov al, bx[2]         ; Error: indexes must occur with "+" as above

   mov bx, Offset ByteVal
                         ; OK: Offset statement does not use brackets

   mov bx, Offset [ByteVal]
                         ; Error:  offset cannot be taken of the contents
                         ; of memory

   lea bx, [ByteVal]     ; OK:  Load effective address of "ByteVal"

   lea bx, ByteVal       ; Error:  brackets required

   mov ax, 01234h        ; OK:  Move constant word to AX

   mov [bx], 012h        ; Warning: size qualifier needed to determine
                         ; whether to populate byte or word

   mov [byte bx], 012h
                         ; OK:  constant 012h is moved to byte at address
                         ; BX

   mov [word bx], 012h
                         ; OK:  constant 012h is moved to word at address
                         ; BX


Ideal mode handles structured records beautifully.  When referring to
structure members the dot operator is used.  The name to the left of the
dot is always the address of a structure and the name to right is always a
structure member.  Ideal mode permits member names to be duplicated in
different structures.  Here is a simple example, again without segment

    Struc PosType
        Row     dw  ?
        Col     dw  ?
    Ends PosType

   Union PosValType
       Pos PosType    ?
       Val dd         ?
   Ends PosValType

   Point   PosValType ?

   mov [Point.Pos.Row], bx   ; OK:  Move BX to Row component of Point

   mov [Point.Pos.Row], bl   ; Error:  mismatched operands


Ideal mode enforces type-size checking even with indirected references.
Using the above structure, here is how indirection is handled.  BX is
assumed to point to an instance of PosValType in memory.  Indirection is
used frequently when pointers are passed to procedures.

   mov [(PosValType bx).Pos.Row], ax
                      ; OK: Move AX to Row component of PosValType instance
                      ; pointed to by BX

   mov [bx + PosValType.Pos.Row], ax
                      ; OK: same as above

   mov [bx + PosValType.Pos.Row], al
                      ; Error:  mismatched operands


The Offset operator always evaluates the offset of a data instance relative
to its group, not its segment.  This allows Offset to be used without
qualifying each reference with the appropriate group name.  Labels in a
segment could be used to determine segment offsets if needed.


Books and files which will be of interest to programmers wishing to know
more about the Ideal mode of Borland's TASM assembler include the

   Turbo Assembler User's Guide / Borland International.
   Naturally, this is the definitive text on Ideal mode.  Its focus is
   strictly on using TASM; it does not cover assembly language or the x86
   instruction set.  Exasperatingly, the examples in the book all use MASM
   emulation mode, and only one of the four complete program examples
   included with TASM (at least version 3.1) uses Ideal mode.  The example
   that does use Ideal mode is a very flexible WHEREIS program.  Studying
   this 13 file example should be sufficient for anyone wishing to
   understand Ideal mode.

   Mastering Turbo Assembler / Tom Swan.
   Indianapolis, IN:  Hayden Books, c 1989.
   This book is not just another Microsoft Assembler book reprinted with a
   Turbo Assembler cover.  Swan uses and promotes Ideal mode throughout.
   This is a great beginning text for programmers who are still hassling
   with the ubiquitous non-reentrant interrupt handler known as DOS.  It
   includes an overview of the x86 instruction set.

   SKEL32.ZIP / Bill Magaletta.
   Obtainable by ftp at hobbes.nmsu.edu:/os2/32bit/program as well as
   ftp-os2.cdrom.com and CompuServe
   This is a standalone 32 bit OS/2 Ideal mode program, the simplicity of
   which will make converts of DOS programmers dealing with interrupts and
   segments.  It includes an overview of the initial register states of
   DOS and OS/2 programs.  This example illustrates the fact that TASM for
   DOS can be used to produce object files for OS/2.

Last changed: 17 Jan 95


Subject: 4. Borland TASM Information

4.1 Borland FTP Site

Borland maintains a ftp site which has a directory dedicated to TASM.  Most
entries are patches and HOW-TOs, but there is a shell for TSRs that will
load and unload either high or low.


4.2 Borland Web Site

At Borland's Web Site, I only could find product and ordering information
on TASM.  The only reference to technical information was a pointer to
Borland's ftp site.

Last changed: 11 Nov 95


Subject: 5. Borland tools/Windows 95 Interworking Patches Available


Using the 32bit tools from Borland C++ 4.5 / TASM 4.0 under Windows 95 can
fail when the DOS based tools tools are called from the Windows IDE.

The nature of the problem is that any attempt to specify a commands file

Windows 95 long filenames, and the TASM32.EXE file-open code.

launching TASM32.EXE if 32bit instructions (which are not handled by the
inline C++ assembler) are encountered in a user's source.

Although the Borland tools reportedly use the PowerPack DPMI extensions for
their 32bit operation, user applications which use the Powerpack libraries
do not seem to be affected by this problem.

A patch is available to correct this issue from location:

This should be applied using the patcher executable from location:

Last changed: 19 Feb 96


Subject: 6. Borland TASM List Server                        REVISED


Believe that this list server no longer is available.  Any one with
information, please contact the author.  There is a list server available
that is devoted to Borland's TASM Assembler.


To join send e-mail to:

with the phrase
    subscribe TASM-L your name
in the text.


To send e-mail to all members, send the e-mail to:

Last changed: 22 Feb 97


Subject: 7. FREELIB, Version 3.0

Freelib v3.0 is a library of 200 routines that may be useful for assembly
language programming.  Freelib includes routines that do many of the
tasks that make assembly language difficult - like buffered file I/O,
formatted string output, memory allocation, etc.  Also includes 16.16bit
fixed point arithmetic, text screen output (EGA 80x25 or VGA 90x34), and
VGA graphics in both 16 and 256 colors.  All routines are highly
optimized for size and speed, and average only 60 bytes each.  Full
source code and documentation is included for all routines.  Freelib is
public domain software, free for non-commercial use.  The library is
available from SimTel:


Last changed: 20 Dec 96

Wed, 11 Aug 1999 03:00:00 GMT  
 [ 1 post ] 

 Relevant Pages 

1. x86 Assembly Language FAQ - Borland TASM

2. x86 Assembly Language FAQ - Borland TASM

3. x86 Assembly Language FAQ - Borland TASM

4. x86 Assembly Language FAQ - Borland TASM

5. x86 Assembly Language FAQ - Borland TASM

6. x86 Assembly Language FAQ - Borland TASM

7. x86 Assembly Language FAQ - Borland TASM

8. x86 Assembly Language FAQ - Borland TASM

9. x86 Assembly Language FAQ - Borland TASM

10. x86 Assembly Language FAQ - Borland TASM

11. x86 Assembly Language FAQ - Borland TASM

12. x86 Assembly Language FAQ - Borland TASM


Powered by phpBB® Forum Software