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 to both newsgroups and news.answers, alt.answers and
comp.answers. It also is archived at the normal FAQ archival site,
ftp://rtfm.mit.edu and to SimTel and its mirror sites in the msdos/info
directory and Garbo and its mirrors in the pc/doc-net directory. When
uploaded to SimTel or Garbo, the filenames are asmxxyyz.zip, where xx is
the two digit year, yy is the number of the month and z is t for text or
h for HTML format. Lastly, the current version is available from my web
page:
https://www.fysnet.net/faq/index.htm
Zipped down as text files:
https://www.fysnet.net/faq/asmfaq.zip
Zipped down as HTML documents:
https://www.fysnet.net/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 FAQ.
assembly-language/x86/general/part3 - This is a continuation of the
above FAQ.
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 Debugger.
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 on the Internet. I believe
that this will enhance the FAQ’s value not only to the novices but also
to the old hands.
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
period.
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:
http://www.faqs.org/rfcs/rfc1738.html
Suggestions for changes and comments are always welcome. They can be
posted to either newsgroup or e-mailed directly to me.
This FAQ was created and maintained by Raymond Moon before I
took it over. Many thanks to Ray for the effort in creating
this FAQ. Even though most of the links and names have been changed
to mine, the credit still goes to Ray for the work he did. Thanks Ray.
Author: Benjamin David Lunt, fys_at_fysnet.net
Copyright 2024 - Forever Young Software
ALL RIGHTS RESERVED
Last Changed: 24 Jan 2010
Return to the Table Of Contents
------------------------------
Part I
1. Introduction and Intent
2. Table of Contents
3. Charters For comp.lang.asm.x86 and alt.lang.asm Newsgroups
4. What is Assembly Language
5. List of x86 OpCodes
6. What is HELPPC and Where It Is Available
7. How To Truncate a File
8. How Can STDERR Be Redirected To a File
9. How To Determine the CPU Type
10. IRQ Assignments
11. Ralf Brown's Interrupt List
12. Using VGA Mode 13h for Fast Graphics
13. Protected Mode Programming
14. Shareware ASM Libraries
Part II
15. Accessing 4 Gegs of Memory in Real Mode
16. What Is Available at developer.intel.com
17. Interrupts and Exceptions
18. ASM Books Available
19. ASM Code Available on Internet
20. How To Commit a File
21. Using Extended Memory Manager
22. EXE2BIN Replacement
23. ASM Tutorials Available on the Internet
24. Shareware/Freeware Assemblers
25. Undocumented OpCodes
Part III
26. WWW Assembly HomePages
27. Common Reason Why Memory Allocation Fails
28. Volume Serial Numbers
29. File Formats Assosiated with ASM
30. Rebooting from Software
31. Other FAQs
32. Pseudo Random Number Generator in Assembly Language
33. Command Line Arguments
34. Free 32-bit and DJGPP
35. TERSE Programming Language
36. Assembly Language IDEs
37. Disassemblers
38. How to Optimize for the Pentium
39. Assembly Language Programming Style Guidelines
40. Other Assembly-Related Newsgroups
41. ZD-86 Debugger
42. Links to x86 Processor Manufacturers
43. Linkers Available
44. ASM Mailing Lists
45. ASM Programming Journal
46. Acknowledgments
47. PC Operating Systems in Assembly
99. Acknowledgments
[General][MASM][TASM][A86/D86]
------------------------------
Subject: 3. Charters For comp.lang.asm.x86 and alt.lang.asm Newsgroups
To know whether or not these newsgroups will meet your needs, the
purpose for which they were created are given below.
3.1 COMP.LANG.ASM.X86 (CLAX)
comp.lang.asm.x86 was created based upon voting on a Request for
Discussion (RFD). The RFD for this newsgroup is:
The moderated newsgroup comp.lang.asm.x86 will be open to discussions on
all topics related to assembly language and low-level programming on any
machine using a x86 processor or its clones. Appropriate topics would
include, but not be limited to:
Assembly language code tips, tricks, and techniques.
MASM, TASM, and other commercial assemblers
NASM, and other non-commercial assemblers
Graphics, sound, and other hardware programming
Assembly language related utilities commercial/share/free-ware
Linking assembly language with other languages
Inline x86 programming utilizing assembly emulators in higher level
languages
Propagation of non-commercial Internet x86 resources
Any question/discussion of the direct programming of the x86
Etc...
Topics that will be filtered are:
Flames about "{Language X} is {better/worse} than ASM"
Flames like "{Assembler 1} is {better/worse} than {Assembler 2}"
Flames, personal attacks, insults, etc.
HLL code, except when used for low-level hardware programming.
Product comparisons except when presented in an unbiased fashion.
Advertisements unrelated to assembly programming or utilities.
Posts in languages other than English will be examined for approval
if any of the moderators can read the language in question. There
is no guarantee of approval for a post in any language other than
English.
Posting to comp.lang.asm.x86, a moderated newsgroup, is not any
different for you as posting to an unmoderated newsgroup. When you are
finished composing your post just send it as you normally do. Your
ISP’s news server will send the post to the moderator’s e-mail address.
Once approved, the moderator will post it. Therefore, you will not see
your postings immediately in the newsgroup. It should take no longer
than a day or so to see it.
If your ISP does not carry this newsgroup, you can send your post directly
to the email mentioned above using the following address:
mailto:clax86-submit@inspiretomorrow.net
3.2 ALT.LANG.ASM
Alt newsgroups are initiated with a Proposal posting to the alt.config
newsgroup. The proposal for alt.lang.asm is:
alt.lang.asm will address the problems of machine language programmers
out there in Internet land. It will be a forum for discussion of coding
techniques and efficiency problems related to machine language. The
scope will be broad. We will not discriminate by machine architecture,
race or sex.
3.3 Posting Guidelines
The following are simple guidelines to help you post to the above
newsgroups. These simple guidelines are just that, simple. They're not
rules written in stone, just guidelines. Please consider them when you
are posting new messages and replying to existing messages.
- Please use a somewhat detailed subject line. A line such as "help me"
is not considered detailed, where as "8086 SALC instruction help"
is detailed. Please note that some newsreaders truncate a long
subject line.
- Please do not place part of the subject on the subject line and
the rest of the subject in the body of the message.
- Please do not ask a question via the subject line.
- If you are replying to a message, please see that only one "re:" is
prefixed to the subject, rather than multiple 're:'s.
- If you are completely changing the subject in the body, please note
in the subject line: re: new subject [was: old subject]"
- Please keep cross posting to a minimum between the two mentioned
groups.
- If you *must* ask for a response by email, please make a follow-up post.
In this follow-up, please do not just include all original emails,
but make a worth-while response to what the outcome of the responses
brought to you and/or the subject at hand.
- Please do not request that someone do your home work or other work
for you. However, you may ask for help with the particular problem
you are having. When asking for help, always describe what you have
already tried yourself and/or what part of the original problem you
don't understand and need help with.
- Please be advised that most newsreaders cut your lines to about
70 chars per line. If you use more chars per line, you may get
linewrap with out the usual prefix char when replying.
- Please do not post binaries. There are other ways to have people
see your binary. A simple URL in the body of your message is
more appropriate than an attachment. Besides, some news servers
reject postings with binary attachments.
- Please keep your text attachments to a minimum and a minimum size.
If the text attachment is only a few lines, post it directly in your
message at the point of interest. However, if you have a text
attachment of 100 lines or more, you may leave it an attachment or
place it at the end of the message. Some newsreaders treat attachments
differently.
- When replying to larger messages, please cut non associated text
from your reply. If needed, please include quotes of the portion
of the previous post to make the current post in context. For smaller
messages, it is okay to leave all text as is.
- Please do not quote an entire long message just to say "thank you".
Quote a small amount to remind the reader about what you are saying
"thank you" to.
- Please use text format for your messages. HTML formatted messages are
not pleasing to most readers.
- Please keep your signature to about 5 lines including blank lines.
Five does not include the '-- ' line.
- If you would like someone to reply to you via email, please either
leave instructions on manipulating your "anti-spam" reply address,
or leave your actual address. Do not assume the reader will
know how to parse your address for "anti-spam" items.
- Please do not add any text to the "end" of your email address. Many
newsreaders will reject posts that don't have a recognizable ending
component (.com, .org, etc.). It is better to place all your "anti-
spam" text before the "@" symbol or the .com|.org, etc.
- If your message is rejected, moderators will usually send you a
notification by email. If any significant effort is required to
notice and/or fix the anti-spam in your email address, the moderators
may not bother with it.
Contributor: Forever Young Software, fys_at_fysnet.net
Last changed: 24 Jan 2010
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------------------------------
Subject: 4. What Is Assembly Language
4.1 WHAT IS MACHINE LANGUAGE?
Although programmers tend to use C, C++ or Pascal these days, the
language closest to the PC hardware is machine language. Not one second
during a PCS powered on lifetime passes where the computer is not
executing machine language.
4.2 ASSEMBLY LANGUAGE OR MACHINE LANGUAGE
To word this simply, you can say that assembly language is a human-readable
text language, and machine language is machine-readable binary code.
When you program in assembly language, you are programming on the
machine language level.
To program directly in machine language is tedious, so you use assembly
language instead, and use an assembler to produce the actual machine
code.
4.3 WHEN TO USE ASSEMBLY LANGUAGE
I personally think that except as a learning exercise it is a waste of
time writing something in ASM that can be written acceptably fast in a
high-level language.
Assembly language fits for the following:
* Low level control. When you need to change the flags, or the
control registers of the processor, as when entering protected
mode.
* Speed. Programs written in machine language execute fast! It can
execute 10-100 times the speed of BASIC, and about twice as fast as
a program written in C or Pascal.
* Time Critical Code. Critical sections of programs written in
higher level languages can be written in assembly to speed up
sections.
* Small program size. When you write a TSR for example this is very
useful. Writing interrupt handlers is where assembly language
shines.
Assembly language is very flexible and powerful; anything that the
hardware of the computer is capable of doing can be done in assembly.
Contributor: Patrik Ohman, patrik@astrakan.hgs.se
Last changed: 03 Mar 2004
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------------------------------
Subject: 5. List Of x86 OpCodes
5.1 x86 OPCODES
The best source of OpCodes up to and including the Pentium 4 processor
is in the Intel Architecture Software Developer’s Manual, Volume 2:
Instruction Set Reference Manual. It is available in .pdf format from
Intel’s Web Site:
http://www.intel.com/Assets/PDF/manual/253666.pdf
5.2 MMX OPCODES
Intel has a chapter covering these new OpCodes in the MMX Technology
Programmer’s Reference Manual. This chapter is Chapter Five - Intel
Architecture MMX Instruction Set.
http://myrasoft.host.sk/texts/mmx/prm_chp5.htm
5.3 OTHER SOURCES OF THESE DOCUMENTS
These manuals are available on the Intel Developer’s CD-ROM, see Subject
#16. You also can find these manuals at:
-- Intel Architecture (IA-32) Software Developer's Manual, Volume 1: Basic Architecture (2008) ( 1997 )
http://download.intel.com/design/processor/manuals/253665.pdf
-- Intel Architecture (IA-32) Software Developer's Manual, Volume 2a (A-M): Instruction Set Reference Manual (2008) ( 1997 )
http://download.intel.com/design/processor/manuals/253666.pdf
-- Intel Architecture (IA-32) Software Developer's Manual, Volume 2b (N-Z): Instruction Set Reference Manual (2008)
http://download.intel.com/design/processor/manuals/253667.pdf
-- Intel Architecture (IA-32) Software Developer's Manual, Volume 3a (part 1): System Programming Guide (2008) ( 1997 )
http://download.intel.com/design/processor/manuals/253668.pdf
-- Intel Architecture (IA-32) Software Developer's Manual, Volume 3b (part 2): System Programming Guide (2008)
http://download.intel.com/design/processor/manuals/253669.pdf
Update to a few typos and what not to above three items.
http://developer.intel.com/design/processor/specupdt/252046.htm
Contributor: Raymond Moon, raymoon@moonware.dgsys.com
Last changed: 24 Jan 2010
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------------------------------
Subject: 6. What Is HELPPC and Where Is It Available
HELPPC is a Quick Reference Utility for the intermediate to advanced
programmer. It is a shareware program written by David Jurgens. The
latest version is 2.10
The topics distributed in an easy database format are:
BIOS interrupts;
DOS interrupts and DOS functions;
EMS and Mouse functions;
BIOS and DOS data structures;
diagnostic codes;
DOS commands;
80x86 assembler instructions;
standard and vendor specific C functions; and
various hardware specifications.
HELPPC is customizable by users. The documentation describes how users
can incorporate their own information into the help file format. These
user help files then can be incorporated into the database and accessed
via HELPPC application.
HELPPC comes in two versions. The first is a DOS command line program.
The second is a TSR. The TSR supports context sensitive help within
many editors. Only 32K are taken by the TSR version.
HELPPC requires:
DOS 2.0 or greater;
64K of RAM for DOS Command Line or 32K for TSR; and
Hard disk recommended.
HELPPC is available from:
ftp://ftp.simtel.net/pub/simtelnet/msdos/info/helppc21.zip
or in web format at:
http://docs.huihoo.com/help-pc/index.html
HELPPC also is available from any site that mirrors the SimTel
directory.
Contributor: Raymond Moon, raymoon@moonware.dgsys.com
Last changed: 24 Jan 2010
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------------------------------
Subject: 7. How To Truncate A File
There is not any single DOS Int 21h function that performs this
operation. A file can be truncated using two functions. The procedure
is:
1. Use Int 21h function 42h, Move File Pointer, to move the file
pointer to the position where you want the file to be truncated.
2. Use Int 21h function 40h, Write File or Device, to write zero bytes
to the file.
Execution of the last DOS function will update the directory to the new
file length.
Contributor: Raymond Moon, raymoon@moonware.dgsys.com
Last changed: 03 Mar 2004
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------------------------------
Subject: 8. How Can STDERR Be Redirected To A File
I understand that 4DOS has this capability at its command line. If you
are looking in the assembly language FAQ for this information, an
assembly language answer probably is desired. Here it is.
You will need to write a short program that performs the STDERR
redirection before loading and executing the desired program. This
loader program relies upon the fact that a child program inherits all
open files of the parent program unless the parent program opens a file
with the inheritance flag set to no.
Because the full code for such a program is too large for this FAQ, I
will give the salient specifications for such a program.
1. The loader program accepts three command line arguments:
a. The full path and filename of the file into which STDERR is to
be written.
b. The full path and filename of the program to be executed.
c. The command line for the program to be executed (should be
delimited by double quotes to allow multiple arguments). This
argument is optional.
2. Release all memory above the program using Int 21 function 4ah so
that there will be room enough to load and execute the designated
program.
3. Open the file from step 1.a above into which STDERR is to be
written.
4. Duplicate STDERR filehandle, which is 2, using Int 21h function
45h.
5. Using Int 21h function 46h, force STDERR filehandle, again 2, to
have the filehandle of the opened file from step 2.
6. Use Int 21h function 4b00h to load and execute the program from
step 1.a. Use the default environment and the command line from
step 1.c above.
7. Upon return from the function 4b00h, close the file opened in step
2.
8. To restore STDERR, use Int 21h function 46h to force STDERR, again
2, to point to the filehandle saved from step 3 above.
This same technique can be applied to any of the standard devices.
I have written a full featured demonstration program. I believe that
asm programmers will find the source code useful even if they do not
want to redirect stderr to a file. The URL to the file is:
ftp://ftp.simtel.net/pub/simtelnet/msdos/asmutl/stderrf1.zip
Contributor: Raymond Moon, raymoon@moonware.dgsys.com
Last changed: 03 Mar 2004
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------------------------------
Subject: 9. How To Determine The CPU Type
9.1 CPUID PROGRAM
The type of processor and math coprocessor can be determined using two
functions that have been provided by Intel. The source code to these
functions can be obtained from Intel by:
ftp://ftp.intel.com/pub/IAL/tools_utils_demos/cpuid3.zip [broken]
Three source files are included in this .zip file.
cpuid3a.asm - This source code file contains two assembly language
functions. One determines the type of cpu from 8088/8086 to
Pentium. The second detects and identifies, if present, the
type of math coprocessor.
cpuid3b.c - a c program that calls the above two functions and
displays the results.
cpuid3c.asm - this is an assembly program equivalent to cpuid3b.c.
There are documents by Intel here:
http://software.intel.com/en-us/articles/intel-64-architecture-processor-topology-enumeration/
And AMD here:
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/25481.pdf
With others here:
http://www.cpuid.com/
9.2 AP-485 INTEL PROCESSOR IDENTIFICATION WITH THE CPUID INSTRUCTION
This Application Note explains how to use the CPUID instruction in
software applications, BIOS implementations, and various processor
tools. By taking advantage of the CPUID instruction, software
developers can create software applications and tools that can execute
compatibly across the widest range of Intel processor generations and
models, past, present, and future.
http://www.intel.com/Assets/PDF/appnote/241618.pdf
9.3 Robert Collins' CPUID.ASM
Robert Collins has written two columns for Dr. Dobb’s Journal on this
subject. These articles with source code is available on his web site:
Part 1: http://www.rcollins.org/ddj/Sep96/Sep96.html
Part 2: http://www.rcollins.org/ddj/Nov96/Nov96.html
9.4 Grzegorz Mazur's x86 CPU Identification
Grzegorz has a series of hypertext articles that explain x86 CPU
identification algorithms developed by him. Covered are not only the
Intel chips but also V20, V30 (remember them), and Cyrix. His page is
located:
http://grafi.ii.pw.edu.pl/gbm/x86/ [original link]
http://web.archive.org/web/20080419091140/http://grafi.ii.pw.edu.pl/gbm/x86/ [via WayBackMachine]
Contributor: Raymond Moon, raymoon@moonware.dgsys.com
Last changed: 24 Jan 2010
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------------------------------
A list of IRQ assignments are available in David Jurgens' HELPPC
database. See Subject #6 for details on how to obtain this program.
Contributor: Raymond Moon, raymoon@moonware.dgsys.com
Last changed: 03 Mar 2004
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------------------------------
Subject: 11. Ralf Brown's Interrupt List
11.1 FILE AVAILABILITY
The latest version of Ralf Brown's Interrupt List is 61, dated 16 Jul 2000.
The files are available directly from his home page, from SimTel, or
Garbo:
http://www-2.cs.cmu.edu/afs/cs.cmu.edu/user/ralf/pub/WWW/files.html (currently version 61)
ftp://ftp.simtel.net/pub/simtelnet/msdos/info (currently version 60)
ftp://garbo.uwasa.fi/pc/programming
http://www.ctyme.com/rbrown.htm Online version (recommended)
The files are:
inter61a.zip Comprehensive listing of interrupt calls, 1 of 4
inter61b.zip Comprehensive listing of interrupt calls, 2 of 4
inter61c.zip Comprehensive listing of interrupt calls, 3 of 4
inter61d.zip Comprehensive listing of interrupt calls, 4 of 4
inter61e.zip Utility programs/source code for interrupt list
inter61f.zip Hypertext conversion programs for interrupt list
11.2 DESCRIPTION
The interrupt list is a comprehensive listing of functions available
through interrupt calls and FAR calls, both documented and (officially)
undocumented, plus maps of CMOS and BIOS memory, I/O ports, I2C-bus
devices, and System Management Mode save areas. This release contains
more than 9500 entries and over 5300 tables.
11.3 WHAT IS NEW
New in this release: Start of an FAQ, 400k of additions, including:
AHA-154x commands, ATASPI, more MSRs (including AMD Athlon), lots of
DR-DOS/OpenDOS/PTS-DOS/S-DOS info (with more still to be added), AMIGATSR,
MULTIJOY, USB4DOS, VXDLDR, etc.
INTERxxF and INTERxxG have been merged, and OPCODES.LST has been updated.
11.4 OTHER INCLUDED GEMS
OVERVIEW.LST - A brief description of each of the 256 interrupts.
86BUGS.LST - A list of undocumented and buggy instructions with
descriptions of the x86 Intel processor and compatible
processors. And you thought that the Intel FDIV was the first
bug in a processor!
CMOS.LST - a CMOS memory map.
OPCODE.LST - A list of undocumented instructions and documented
instructions of any last processor.
PORTS.LST - I/O port addresses for XT, AT and PS/2 computers.
GLOSSARY.LST - glossary of PC terms.
MEMORY.LST - The format for various memory locations, such as the
BIOS Data Segment, Interrupt Vector Table, and much, much more.
INTERRUP.PRI - iAPX 86 Interrupt Primer
Contributor: Raymond Moon, raymoon@moonware.dgsys.com
Last changed: 24 Jan 2010
Return to the Table Of Contents
------------------------------
Subject: 12. Using VGA Mode 13h for Fast Graphics
12.1 INTRODUCTION AND PREPARATION
Mode 13h is so widely used for graphics applications in DOS because it
is very easy to use. The screen is constantly being redrawn by the
video card. To affect what the card draws, it is necessary to write to
the screen buffer. The screen buffer in mode 13h is always at
segment:offset = A000:0000. Thus, to set up drawing directly to the
video buffer, this is what you'd most often first do:
;Change the video mode to 13h
xor ah, ah ;VIDEO Function 00h: Change screen
mov al, 13h ;Put the desired graphics mode into AL
int 10h ;Call VIDEO
;Prepare for writing to the video buffer
mov di, 0a000h ;Put the video segment into DI
mov es, di ; so it can easily be put into ES
xor di, di ;Start writing at coordinates (0,0)
12.2 WRITING PIXELS TO THE SCREEN
Why is Mode 13h so popular? To understand, you must know a few basic
facts. In Mode 13h, the screen is 320 by 200, or 320 pixels across and
200 pixels down. In each pixel, there's a possibility of 256 colors,
which can be fit into one byte. Thus, 320*200*1 = 64000 bytes, about
the size of one segment. Think of the screen as an array of colors.
The first row takes up addresses A000:0000 to A000:013F (decimal 319),
the second row takes up addresses A000:0140 to A000:027F (decimal 639),
and so on. To plot a pixel, assuming ES=A000:
;Plot a pixel in video mode 13h, where
;PixelAddress = (320 * Y) + X
mov ax, 320 ; Prepare for the multiplication
mul [Y] ; Assuming that Y is defined in the data segment
; earlier in the program
mov di, ax ; Put in into the pointer to the offset of ES
add di, [X] ; Assuming that X is defined in the data segment
; earlier in the program
mov al, [Color] ; Assuming that Color is defined in the data
; segment earlier in the program
stosb ; Write it to the screen!
See how easy that was? Something to remember is that it is zero-based.
The upper-left corner is (0,0), and the lower-right is (319,199). A
complete TASM Ideal mode procedure might look something like this (it
assumes that the video card is already set to mode 13h):
PROC WritePixel BASIC ; Or whatever language you might want to link
; it to
USES es, di ; It's always a good idea to preserve ES and DI
ARG X:word, Y:word, Color:BYTE
mov di, 0a000h ; Put the video segment into DI
mov es, di ; so it can easily be put into ES
mov ax, 320 ; Prepare for the multiplication
mul [Y] ; Offset pointer by the Y value passed in
mov di, ax ; Put in into pointer to the offset of ES
add di, [X] ; Offset the pointer by the X value passed in
mov al, [Color] ; Put color to be written to the screen in AL
stosb ; Write it to the screen!
ret
ENDP WritePixel
To write a horizontal line, just put the length in CX, and replace the
STOSB with a REP STOSB. Writing a vertical line is only a little
trickier. Observe the following TASM Ideal mode procedure:
PROC VerticalLine BASIC ; Or whatever language you might want to link
; it to
USES es, di ; It's always a good idea to preserve ES and
; DI
ARG X:word, Y:word, Color:BYTE, Length:word
mov di, 0a000h ; Put the video segment into DI
mov es, di ; so it can easily be put into ES
mov ax, 320 ; Prepare for the multiplication
mul [Y] ; Offset the pointer by the Y value passed in
mov di, ax ; Put in into the pointer to the offset of ES
add di, [X] ; Offset the pointer by the X value passed in
mov al, [Color] ; Put the color to be written to the screen
; in AL
mov cx, [Length] ; Prepare for the loop
YLoop:
stosb ; Write it to the screen!
add di, 319 ; Move down one row (DI has already advanced
; once because of the STOSB, thus the 319)
loop YLoop
ret
ENDP VerticleLine
Observe how there is a tight loop that moves DI down one row each
iteration.
In short, the easiest way to write directly to the Mode 13h video buffer
is to think of the screen as just a 320 by 200 array of bytes, starting
at A000:0000.
Author: Michael Averbuch (mikeaver@prairienet.org)
Last changed: 03 Mar 2004
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------------------------------
Subject: 13. Protected Mode Programming
13.1 PMODE Tutorials, FAQ, and other reference documentation
Protected Mode Basics by Robert Collins
http://www.rcollins.org/articles/pmbasics/tspec_a1_doc.html
Excellent starting tutorial with source code.
PMODE FAQ
ftp://ftp.simtel.net/pub/simtelnet/msdos/asmutl/pmtut002.zip
Protected Mode Book List
http://www.interactive.net/~viren/Janz/Books/pmode_books.htm [Broken]
Christopher Giese’s PMODE Tutorial
http://files.osdev.org/mirrors/geezer/os/pm.htm
HTML format
pmode-l FAQs
http://www.lysator.liu.se/~redhog [Broken]
http://phantom.urbis.net.il/bphantom/pmode-l_FAQ.html [Broken]
13.2 Source code Archives
Walnut Creek PMODE Archives
ftp://ftp.cdrom.com/pub/demos/code/hardware/pmode/ [Broken]
X2FTP.OULU.FI
http://ftp.lanet.lv/ftp/mirror/x2ftp/msdos/programming/pmode/00index.html
Protected mode utilities and some source code
13.3 PMODE Websites
Peter's PMODE Home Page
http://www.geocities.com/SiliconValley/Peaks/1231/ [Broken]
PMODE tutorials and programming related files
Niko Komin's Assembler for PCs page
http://home.snafu.de/nkomin/html/assembe.htm
Shareware, pmode, x86 mnemonics, ASM related links.
http://www.alaska.net/~zumwalt [Broken]
Archives, Source Code, Technical Documentation, OS Chat Room
and much more
PASS-32, Dieter's Assembler
http://freenet-homepage.de/dieterp/
Debugger and DOS extender also available
Dario Alpern's programs
http://members.tripod.com/~alpertron/ENGLISH2.HTM
PMODE examples
Christopher Giese’s Triple Fault Club
http://files.osdev.org/mirrors/geezer/os/index.htm
NASM and DJGPP Code, Protected Mode Code, OS Code
13.4 PMODE Mailing Lists
Protected Mode Mailing list:
To subscribe:
Send: mailto:pmode-l-request@fys.ruu.nl
subject: none
body: subscribe pmode-l email@yourisp.name (Note that is pmode-l
(ell) not pmode-1 (one)
Use pmode-l@fys.ruu.nl to send email to others in the list.
To unsubscribe:
Send: mailto:pmode-l-request@fys.ruu.nl
subject: none
body: unsubscribe pmode-l email@yourisp.name
Contributor: Raymond Moon, raymoon@moonware.dgsys.com
Last changed: 24 Jan 2010
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------------------------------
Subject: 14. Shareware ASM Libraries
14.1 ASMLIB PROGRAMMER'S TOOLKIT, VERSION 4.0
Douglas Herr's shareware assembly language library. This library is
available from SimTel.
ftp://ftp.simtel.net/pub/simtelnet/msdos/asmutl/asmlib40.zip
The zip file contains only the medium model of the library. There are
405 assembly subroutines in a .lib file and documentation. Source code
is available with registration and extra fee. The library covers the
following areas:
string/integer data manipulation screen mode subroutines
text-mode multi-window subroutines disk & file subroutines
text-mode video subroutines EMS and XMS subroutines
floating-point subroutines graphics
keyboard input subroutines mathematical solutions
subroutines which determine PC status
asmlib40 also comes with an editor, E16, written entirely with asmlib.
Improvements since version 3.7 is auto-sizing of the near heap in the
startup code. There have been some incremental improvements including
32k-color graphics and virtual graphics screens.
14.2 THE ASSEMBLY WIZARD'S LIBRARY, VERSION 2.1
This is Chris Walker’s shareware assembly language library. This
library used to be Thomas Hanlin's.
ftp://ftp.simtel.net/pub/simtelnet/msdos/asmutl/asmwiz21.zip
This library comes with documentation and one .lib file that supports
small and tiny memory models. Source code is available with
registration. The library covers the following areas:
Base Conversions Mouse Services
Exception Handling Sound and Music
Delays and Countdowns String Services
File Handling Telecommunications
Filename Manipulation Time and Date
Keyboard Services Video Services
Long Integer Math Miscellaneous Services
Memory Services
14.3 UCR Standard Library for Assembly Language Programmers
This library is written by Randall Hyde and others. This library is
available from many sites but most of them are seriously out of date.
You can get the latest version at:
http://homepage.mac.com/randyhyde/webster.cs.ucr.edu/HighLevelAsm/HLADoc/HLAStdlib_info.html
Unlike the previous libraries, there are no registration fees and the
included source code is released to the public domain. The author does
request that if you use the library, you contribute at least one routine
to the library.
Standard Input Routines Character Set Routines
Standard Output Routines Memory Management Routines
Conversion Routines String Handling Routines
Utility Routines
14.4 ALIB Version 4.0
ALIB is Jeff Ownens' shareware assembly language library. This library
is available from SimTel.
ftp://ftp.simtel.net/pub/simtelnet/msdos/asmutl/alib40.zip
Similar to the UCR library described above, registration fees are not
requested. The library consists of over 400 assembly source files
covering the following areas:
compress - data compression and expansion
config - program configuration, colors, paths, etc.
compare - compare strings
convert - hex/decimal/ascii conversions
database - simple database functions
disk - disk information, path changes, file searches
display - fast display functions, write to display memory
error - error handlers
float - simple floating point math package
math - dword math, crc, roots
memory - memory manager, extended, xms, ems, conventional
menu - menuing system
message - messages in windows on screen
misc - misc routines
mouse/key - mouse and keyboard functions
parse - extraction of parameters from command line
random - random number generators
search - search for character or string
sort - sort buffer or file
sound - sounds
string - ascii string handling
stdout - characters, strings, spaces to stdout
system - system interrogation and setup
time - time and date conversions
Also included are 15 sample programs.
14.5 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:
ftp://ftp.simtel.net/pub/simtelnet/msdos/asmutl/freeli30.zip
Contributor: Raymond Moon, raymoon@moonware.dgsys.com
Last changed: 23 Nov 98
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