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*** MASTER*KEY - Version 2.2 *** COPYRIGHT, 1985, 1986, 1987 - LARRY G. GRIMES ALL RIGHTS RESERVED. NO PART OF THIS MANUAL OR SOFTWARE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS WITHOUT WRITTEN PERMISSION OF THE AUTHOR. PUBLISHED BY: SHARPE SYSTEMS CORPORATION 2320 "E" Street La Verne, CA 91750 (714) 596-0070 * * * * * * * * * * * * CAUTION ! * * * * * * * * * * * * * * * * REVIEW YOUR SOFTWARE LICENSE AGREEMENTS BEFORE USING * * THESE PROGRAMS - Some product manufacturers specific- * * ally forbid the alteration, disassembly, reverse- * * assembly, or unassembly of their software. This * * product was not intended to violate anyone's rights * * or to assist anyone to infringe on the rights of * * another to receive compensation for the effort, money, * * and time consumed in the development and production * * of software. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * WARNING ! * * * * * * * * * * * * * * * * THIS MANUAL AND SOFTWARE ARE PROTECTED BY UNITED * * STATES COPYRIGHT LAW (Title 17 U.S. Code). THE UN- * * AUTHORIZED REPRODUCTION AND/OR SALE OF THIS PRODUCT * * MAY RESULT IN YOUR IMPRISONMENT OF UP TO ONE YEAR IN * * A FEDERAL PENITENTIARY AND A FINE TO $10,000 * * (17 USC 506). COPYRIGHT INFRINGERS AND VIOLATORS ARE * * ALSO SUBJECT TO CIVIL LIABILITY AND PUNITIVE DAMAGES. * * BE AWARE OF THE CONSEQUENCES OF YOUR ACTIONS. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * .PA SOFTWARE LICENSE AGREEMENT: --------------------------- You are not given possession of this software. You only have a license for the non-exclusive use of the programs for as long as the copyright is in effect and valid. You are to treat this software as you would a book or any other copyrighted material. It is not possible for more than one person to read a book at the same time, likewise, this copy of software may not be used by more than one person on one computer at a time. You are not to give copies of the documentation or programs to anyone for any reason. This software is not to be used in a computer network, bulletin board, or any other form of general access. The purchase and use of this software package is evidence of the agreement to abide by the provisions of this agreement. It is against the law and in violation of United States Copyright to make copies of this documentation or copies of this software for other than backup purposes. This software is provided "AS IS" and includes NO WARRANTY, express or implied. The complete risk of its use rests with the person using it. The manufacturer, dealer, or representative is is in no way liable for any damages resulting from the use of this software, both direct and indirect. There is NO GUARANTEE of its accuracy, correctness, currentness, or reliability. This agreement and license is governed by the laws of the United States of America and the state of California. ACKNOWLEDGMENTS: ---------------- MASTER*KEY is a trademark of Larry G. Grimes. IBM and PC-DOS are trademarks of the International Business Machines Corporation. MASM, Microsoft, Microsoft Basic, MS, and MS-DOS are trademarks of the Microsoft Corporation. Norton Utilities is a trademark of Peter Norton. UNIX is a trademark of Bell Laboratories. .PA INTRODUCTION: ------------- MASTER*KEY is tool or a utility to enhance other tools and reference materials in understanding and programming your personal computer in assembly or machine language. It is not an editor or assembler. You must use other software tools for these functions. MASTER*KEY is an intelligent MS-DOS disassembler or reverse- assembler. It produces easily-readable self-documented assembly language source code files from machine language or object code that may be edited with any ASCII file text editor or word processor, then re-assembled using a debugger, assembler, or macro assembler and linked with other object modules if desired. It handles object code from the 8088, 8086, 8087, 80186, 80286, and 80287 processors. It decodes into MS-DOS 2.0, 2.1, 3.0, 3.1, and 3.2. MASTER*KEY includes an 8086 assembly language source code formatter & cross-reference generator. The formatter produces an easy- reading documented source listing identifying all ROM BIOS and DOS functions & interrupts. It serves as an object code optimizer by helping to identify stack areas, temporary storage, ASCII strings, and unnecessary code. The cross-reference identifies the number and location of all labels, symbols, functions, and interrupts. 8087, 80287, 80186, 80286 specific code is flagged, but not fully expanded and formatted. The source code produced can be immediately assembled with Microsoft's MASM 4.0 or less. The code is highly compatible with other assemblers using Intel's instructions. MINIMUM SYSTEM REQUIREMENTS: ---------------------------- 1. An 8088/8086/80186/80286-Based Personal Computer (close to IBM-compatibility) 2. At least 256K RAM 3. DOS 2.0, 2.1, 3.0, 3.1, OR 3.2 4. At least one 360K DSDD Floppy Drive (IBM PC Format) (a fixed or RAM disk is highly recommended) .PA WHAT YOU SHOULD KNOW BEFORE USING MASTER*KEY: --------------------------------------------- 1. To examine programs for compatibility or suitability. a. Operation and use of an IBM PC or compatible computer and DOS. b. A basic understanding of the 8086 family object and source code. c. Familiarity with DOS & ROM BIOS functions & interrupts. 2. To make minor alterations. d. The use of a debugger and executable program modifier such as Microsoft's DEBUG, SYMDEB, Peter Norton's Utilities, etc. 3. To completely re-assemble new programs. e. An extensive knowledge of all the above. f. 8086 assembly language programming, preferably with Microsoft's MASM to 4.0. .PA GETTING STARTED: ---------------- Copy the files from the original disk to a backup disk and a working floppy or hard disk and store the original for safekeeping. Always keep backups of everything. Refer to your DOS manual for procedures if necessary. Files included on the disk: 1. MK.EXE MASTER*KEY Program. The major disassembling program to allow you to view, print, or create a file of documented source code from machine language in different formats. To run, type in and press return: MK filename.ext Example: MK MK.EXE will disassemble itself. "filename" is any file, it would usually be an executable program with an extension of .COM or .EXE. The file may also be a device driver, overlay, or code fragment with no extension, .SYS, .BIN, .OVL, .OVR, .HEX, etc. Pressing the SPACE BAR will stop & restart the scrolling display. Pressing ANY OTHER key on a motionless display will invoke the Lotus-style command menus. Pressing the right & left cursor keys, space bar, home & end keys will browse through the choices. Pressing 'C' will continue the scrolling display. Pressing the selection number or RETURN after moving to a desired option will select the option. 2. MKX.EXE MASTER*KEY Cross-Reference Program. The program to print a cross-reference or produce a file with an extension of .XRF by hexadecimal location of a file with an extension of .DIS created ONLY by MK.EXE. To run, type in and press return: MKX filename (don't include extension) Example: MKX MK will create MK.XRF if MK.DIS is valid. 3. MKDATA.EXE MASTER*KEY Data-Reference Program. The program to quickly create data statements in MASTER*KEY disassembled format. Locates most, but not always all ASCII data in ANY file. To run, type in and press return: MKDATA filename.ext Example: MKDATA MK.EXE will display on screen. MKDATA MK.EXE >MK.DAT will be redirected to the file MK.DAT. NOTE: MKDATA will accept command line arguments -B, -H, and -T the same as MK.EXE. 4. README Additional information included if necessary. 5. MK.TXT MASTER*KEY Manual-on-the-disk. NOTE: To DISPLAY the README, MK.TXT or any other of the ASCII files (DIS, XRF, DAT) type in and press return: TYPE filename.ext To PRINT the the ASCII files type in and press return: TYPE filename.ext >PRN ( >PRN redirects the output from the screen to printer). USING MASTER*KEY: ----------------- To run MASTER*KEY, the program must be in the current directory or in a directory specified with the latest PATH command: EXAMPLE: PATH=A:\DOS;B:\MK With this path command, if MASTER*KEY is not in the current directory, it will run from any DOS prompt if it is in A:\DOS or B:\MK. Refer to your DOS manual if you have any trouble understanding the environment path or the use of directories and subdirectories. Speed is increased dramatically if files are read from a RAM disk. MASTER*KEY'S INTERACTIVE MODE: MASTER*KEY offers a number of interactive commands. Commands are the instructions you give MASTER*KEY to perform a variety of different tasks, such as scrolling the documented source code of any executable program, finding all the terminating interrupts in a program to see why it seems to be quitting prematurely, or finding the references to a particular piece of data. COMMAND MENUS: Command menus are the method used by MASTER*KEY to present selection alternatives to the user. The command menus are very similar to those used by Lotus Corporation's 1-2-3 or Symphony. In interactive operation, to display the command menus, press the space bar to suspend the scrolling of the screen, then any other key (pressing the space bar again will continue scrolling). The currently available command choice is highlighted with a large cursor. Pressing the right & left cursor keys, space bar, home & end keys will browse through the choices. Pressing 'C' will continue the scrolling display. Pressing the selection number or RETURN after moving to a desired command will select the option. MASTER*KEY'S AUTOMATIC MODE & COMMAND LINE FLAGS: mk [infile] [-flags...] Command line flags allow automatic operation or setup from the DOS prompt or a DOS batch file. Such operation is only needed by the most experienced of programmers with massive fixed disk capacity, since a very large file can be created in such a short time. And such a file is relatively useless unless you're going to reassemble the entire file which will take a lot of work from the best of assembly language programmers. MASTER*KEY can do such work, but its strength is in its inter-active nature and the ability to abstract a small amount of important information from a potentially impossible-to- understand mass of source code. Anything in square brackets is optional, infile is not required, but if omitted MASTER*KEY will display an outline of command line options. If the program is continued, the infile will have to be entered from the main menu. This file is read from disk by sector as necessary. The file is not resident in RAM because of the memory requirements just to run MASTER*KEY. If you have 640K of RAM, or extended memory in your system, it's highly recommended you use a RAM disk (one in expanded memory is great!). If an output file name is specified on the command line, MASTER* KEY will work only in batch mode. If not, MASTER*KEY work only in the inter-active mode. In other words, to run MASTER*KEY automatically, you must use an output file name. If any of the file names or flags is incorrect, MASTER*KEY will terminate with an error message. EXAMPLE: MK MK.EXE -B0A000 -E0B000 -L -OMK In the example, MASTER*KEY will automatically find branch addresses and disassemble itself into the disk file MK.DIS from program file offsets 0A000h to 0B000h and exit. COMMAND LINE FLAGS: -B<hex#> Beginning Offset. Sets the offset to start disas- sembling, rather than the default 100h for .COM and the instruction pointer .EXE files. Can be up to 5 hexadecimal digits. -CC Output ALL Code (similar to MS-DOS debug). -CD Output ALL Data. -CI Output Exceptions Only (funcs, int's, sgmt chgs). -CB Output Branch Ref's Only. -CR Output Data Ref's Only. -CO Output Data Only. -E<hex#> Ending Offset. Sets the offset to stop disas- sembling, rather than the default end of file. Can be up to 5 hexadecimal digits. -H<hex#> Code origin or PSP Header Size. Changes the default PSP size of 100h for non-EXE files such as device drivers, code fragments, and programs loaded at static locations. You may use DEBUG to break a large file into several smaller files and use the code origin of each file to maintain correct addressing. -L Load Branch Address Array. It is a good idea to use this flag if you need to reference all of the branch locations, since it takes some time to accomplish. -O<string> Output File Name, to be use by the MASTER*KEY cross- reference, it must have the extension: .DIS. -Q<0-2> Video BIOS selection (for Non-IBM Compatibles). 0 = Write Screen Display directly to Video memory. Default & fastest. If your computer is not completely IBM video-graphics BIOS compatible, you may need to use Q1 or Q2. 1 = Do not use Video BIOS (extremely slow). Screen output is totally software simulated. 2 = Use Video BIOS, but remove snow (somewhat slower). The screen refresh is slowed down. -T<0-9> Change Tab Spacing on output to file or printer. The default value is 8. Tab Characters are used to fill large blank areas on the listings and keep file sizes to a minimum. If your printer does not recognize tabs, the output will not be aligned properly. Also, your editor may have different spacing for tabs (C programmers tend to use 3 or 5). The default value is 8. An entry of -T or -T0 will disable tab characters completely. You MUST disable tabs with some non-IBM compatible printers. -V If your computer doesn't seem to be Video Display compatible with MASTER*KEY, -V with no arguments will attempt to interpret the given display colors and attributes. If the result isn't satisfactory, use VA or VC. These arguments are for true IBM- compatibility (you may need to experiment with different combinations to achieve the desired display colors and attributes, also refer to your technical reference manual): MASTER*KEY IBM-PC Video Display Colors: Color Hex Value Black 0h Blue 1h Green 2h Cyan 3h Red 4h Magenta 5h Yellow 6h White 7h MASTER*KEY IBM-PC Video Display Attributes Color Display: Attribute Hex Value Binary Mask Normal 0h 0000b Reverse 1h 0001b Bright 2h 0010b Reverse Bright 3h 0011b Blink 4h 0100b Reverse Blink 5h 0101b Bright Blink 6h 0110b Reverse Bright Blink 7h 0111b Monochrome Display: Attribute Hex Value Binary Mask Normal 0h 0000b Reverse 1h 0001b Bright 2h 0010b Blink 4h 0100b Reverse Blink 5h 0101b Bright Blink 6h 0110b Reverse Bright Blink 7h 0111b Underline 8h 1000b Underline Bright Ah 1010b Underline Blink Ch 1100b Underline Bright Blink Eh 1110b -VA<2hex#'s> Two hex digits for Display Attributes: 1-normal and 2-alternate (default: high-intensity). -VC<4#'s> Four hex digits for Display & Border colors: 1-foreground (text), 2-background, 3-alternate foreground (enhanced), and 4-border. MASTER*KEY RUN-TIME ERROR MESSAGES: ----------------------------------- 1. Can't open input file. The input file was: a. Not on command line, ex: C:>MK INFILE. b. Not on drive, current directory, or path specified. (full pathnames may be used to a total of 50 chars). 2. Can't open output file. a. Not enough directory or disk space. b. Diskette write-protected. c. Existing file attribute may be "read-only". 3. Input file too large or Not enough memory. a. Separate the file into several small logical source code modules to assemble into object code modules to be linked into the final program. This is the way the program was written in the first place. b. Remove any memory-resident programs taking up needed RAM. 4. Invalid input file at line: XX. Cross-reference only. The file was not created by MASTER*KEY or has been altered without MASTER*KEY. 8. Invalid word: XX at line#: YY. Cross-reference only. The file was not created by MASTER*KEY or has been clobbered. 9. Command Line argument invalid: XX Correct & retype command line or batch file. 10. Untrapped error : SyLongJmp (-XXX) General fatal error message. Usually caused at start for lack of available memory for dynamic memory requirements. MASTER*KEY MENU MESSAGES: ------------------------- Main Menu: CONT, 1-OFFSET, 2-OUTPUT, 3-EXIT, 4-FILE INFO, 5-MISC, 6-INPUT, 7-HELP C - Continue current display This selections returns to scrolling display or file output. 1 - Change offset from beginning of file Allows entering or editing previously entered beginning and ending offsets from beginning (code area for .EXE files) of object file. The PSP header size is automatically added for non-.EXE files if offset is less than header. -B and -E argument options on the command line. 2 - Mixed, All Code, All Data, File, Printer, Partial, Window Output Menu Selections. 3 - Return to DOS Leave MASTER*KEY permanently and return to the operating system. When an output file is specified on the command line, MASTER*KEY will automatically return to DOS when completed (if not interrupted). 4 - Display File Header Information Show file name, size, header size, segment info, etc. 5 - Load Branch Addresses, Change Program Header Size, Run External Program Miscellaneous Menu (operations not performed regularly) 6 - Change input file. Allows disassembling a new file with all new default parameters. 7 - Help. Displays a menu map with list of current parameter settings. Output Menu: CONT, 1-MIXED, 2-ALL CODE, 3-ALL DATA, 4-FILE, 5-PTR, 6-PARTIAL, 7-WINDOW C - Return to Main Menu 1 - Change output to MASTER*KEY original mixed dissassembled format Default MASTER*KEY output of combined code and data. A data format, 'DB', is displayed if 8 consecutive printable characters are found, or if a character is duplicated more than 4 times, 'DUP(X)'. When displayed, this may not be data, but coincidental code. You will often see 'phantom data' hidden in your code. You can remove these references using ALL CODE output. 2 - Change output to all code (no data) format No DB's (except for indefinite opcodes, and syntax errors) are displayed. This output will generally correspond with output from MS-DOS Debug. -CC argument option on the command line. 3 - Change output to all data (no code) format ALL object code is displayed in data format, DB. This is useful for removing 'phantom code' from data areas, or creating in-line assembly code for a program from an ASCII file. -CD argument option on the command line. 4 - Turn output in current format to disk file ON/OFF If not already writing to a disk file, MASTER*KEY will allow entering or editing of a previously entered file name, beginning and ending offsets. If already writing to a disk file, selecting this menu option will close the current file and return to the video display. Any valid file name can be used for output, the MASTER*KEY cross-reference program must have a file name with an extension of .DIS. If no extension is indicated, this is automatically appended to the file name. All output will be appended to this file until closed. NOTE: MASTER*KEY will APPEND the current output to an existing file with no indication, so be careful with name selections. After a file has been closed DO NOT use the same file name unless you desire to APPEND the existing data to the file. Use MISC MENU #3 option to execute DOS commands to copy, delete, or rename your disassembled source files. 5 - Turn output in current format to printer ON/OFF Toggles output to current printing device (PRN:). If your printer is not IBM-compatible, does not recognize tab characters, or the tab length is not 8, you will have to change the tab setting from the command line when starting MASTER*KEY. A -T will disable tabs completely and usually solves formatting or alignment problems. Printed output is not available from the command line. 6 - Normal, Int's, Branch Ref's, Data Ref's, Data Only Partial Output Menu. MASTER*KEY's strongest points, the ability to abstract specific documented information from a mass of confusing object code. This is where you begin to find your needle in the haystack. 7 - Turn split screen ON/OFF Toggles the WINDOW function. The video display screen is divided horizontally, providing two windows to view different locations or formats of the same location. The top window is static and cannot scroll. Looking at the same location in ALL CODE and ALL DATA at the same time will help you separate real code from real data. Looking at the actual data and references to it at the same time can be extremely helpful. The same is true for observing branch addresses. Partial Output Menu: CONT, 1-NORMAL, 2-INT'S, 3-BRANCH REF'S, 4-DATA REF'S, 5-DATA ONLY C - Return to Main Menu 1 - Change output to MASTER*KEY original mixed disassembled format 2 - Change partial output to exceptions only (funcs, int's, sgmt chgs) MASTER*KEY's strength, allows weeding out keypoints. -CI argument option on the command line. 3 - Change partial output to branch references only Quickly find locations that call or branch to subroutines and other important code areas. -CB argument option on the command line. 4 - Change partial output to data references only Quickly find all references to a specific data item or items. -CR argument option on the command line. 5 - Change partial output to data only (DB's - no code) Displays only data from MASTER*KEY's mixed format. It is usually much quicker to disassemble large data areas with MKDATA.EXE; use the option for patch areas only. -CO argument option on the command line. Miscellaneous Menu: CONT, 1-BRANCH ADDRS, 2-CHG HDR, 3-EXEC PGM, 4-CHG TABS C - Return to Main Menu 1 - Search file for most branch addresses (may take some time) MASTER*KEY cannot label a branch-to location until it is encountered. Some code deep into the program may branch backwards toward the beginning. This option allows you to automatically find most of the branch points quickly. MASTER*KEY will remember these points as they are encountered and it may take a very long time for a large program. This function is not always needed. -L argument option on the command line. 2 - Change Code Origin or PSP Header Size (ex: 100h for .COM, 0h for .SYS) Allows changing the ORIGIN offset for output. The PSP (Program Segment Prefix) is 256 bytes (100h), and is at the beginning of every regularly executable program in memory. The origin begins at 0h for .EXE programs since their code segment begins at the end of the PSP. The data segment usually begins at the beginning of the PSP, making a 100h difference in references and actual locations of data items. The origin can be any hexadecimal number from 0h to FFFFEh. You may use different code origins for segmenting large files into several source code modules to be assembled separately and linked together later. Since .COM programs only have one segment, their origin is 100h, the end of the PSP. All segment references in these programs are to the beginning of the PSP. Device drivers are executable programs but must have an origin of 0h since they don't use a PSP. You can change the origin for code fragments if you are splitting a program into several different files. This is an excellent idea since a source file can get very large, very quickly. -H argument option on the command line. 3 - Execute DOS Command or other Program from MASTER*KEY Allows leaving MASTER*KEY resident and temporarily executing a DOS command to change directories, a path, copy, delete, or rename a file. You may also execute a completely different program without having to restart MASTER*KEY, such as your text editor or Debug, if you have enough memory, you can even run another copy of MASTER*KEY in another portion of RAM with another file without losing your current parameters. 4 - Remove Tab Characters from Output or Change Tab Length. -T argument option on the command line. DETERMINING OFFSETS & BRANCH LABELS: ------------------------------------ The offsets used by MASTER*KEY are 5-byte REAL ADDRESSES created by adding the 4-digit, 2-byte code segment multiplied by 16 to the 4-digit, 2-byte offset: CODE SEGMENT: 1000h * 16(10h) = 10000h OFFSET: 1000h + 1000h --------- REAL ADDRESS: = 11000h BRANCH LABEL: = H11000 EXAMPLE: H00100: JMP H00105 NOP NOP H00105: RET INDEFINITE FUNCTIONS: If a function or interrupt is unclear to MASTER*KEY, it is indicated with: ;INDEF_FUNC This is caused by a non-DOS interrupt, or the contents of the AH register may be unclear or variable. You will have to determine on your own the purpose of these interrupts. Subroutine calls are indicated with: ; . . . . . . . . . This allows you to locate them easily and fill in the function for you own documentation if desired. Unconditional branches are indicated with: ;-------------------------------------- This allows for easy reading of the formatted source file output, and possible data and non-branched code areas are indicated if there is no branch address label following the unconditional branch. Be careful, there may be a hidden reference or the branch may be word-aligned: JMP H01200 ;-------------------------------------- NOP H01100: MOV AX,BX *** CAUTION *** A branch label may exist here, but may be a FAR label from another object module. If this is the case, there may be up to 15 bytes of garbage after the previous unconditional branch may exist before the branch address that may or may not be recognized by MASTER*KEY. When disassembling always anticipate the unexpected, and don't make dangerous assumptions. Areas of repetitive bytes are indicated in groups of 256 or less with: DB 256 DUP(XXh) DB 22 DUP(XXh) MASTER*KEY does not directly interpret 8087, 80186, 80286, and 80287 instructions. Most are indicated in the source listing, and must be manually edited if necessary. HOW TO USE MASTER*KEY: --------------------- MASTER*KEY works somewhat similar to the MS-DOS DEBUG program's unassemble function. MASTER*KEY goes much further than to just be a disassembler. With selective partial output you can easily understand how an executable object code file or program actually operates. The last thing you should do is create a complete source file right away. An object code program can easily become more than 20 times its original size when it is turned into source code. This complete source listing or file is almost as unmanageable as the program in the first place. Only an experienced assembly language programmer should even attempt to totally disassemble and reassemble a complete program. Very few programs, if any of any value, can easily be disassembled and reassembled without a great amount of re-editing. MASTER*KEY can create a source file, but much work will be required to get it running again. It is best to use Debug or some other utility to change the object code directly as long as you don't change the size of the program in any way. Changing the code size may destroy branch points and data locations. The major purpose of MASTER*KEY is to help you accomplish this purpose. The easiest way to convert discrepancies so a file will reassemble is to convert the necessary object code verbatim using DB's. Sometimes an area of code is actually data too difficult to discern. It may be a table or a collection of control codes. Changing the values may be disastrous. To disassemble ROM, or any area in memory, use DEBUG to create a file. MASTER*KEY will only work with disk files. HOW TO DISASSEMBLE A PROGRAM: ----------------------------- Start with data. Run MKDATA.EXE to find the data areas and locations. To find a program feature, it doesn't make much sense to disassemble the data areas. Create a file of functions and interrupts only. This will lead you to key areas by just using the cross-reference of this file. Since the cross-reference is by location, you really don't need a long listing of source code. Just use the cross-reference as a map to scroll through the file using MASTER*KEY in its interactive mode. Using the windows, mixed-mode, and partial output is much more effective and motivating than trying to decipher a source code listing on a stack of paper over an inch thick. MASTER*KEY's interrupt messages to pay careful attention to are: 1-Create_Pgm_Sgmnt BAT-Chg_Disk_Status 1-DTA_Address BAT-Dev_Event_Wait 1-FAT_Any_Drive BAT-Dev_Prgm_Term 1-FAT_Current_Drive BAT-Ini_HD_Prm_Tbls 1-Set_DTA BAT-Recalibrate_Dr 1-Set_Intrpt_Vector BAT-Seek_to_Cyl 1-TERM_normally BAT-Set_Disk_Type 2-Allocate_Memory BAT-Set_Flg_Cmp_Int 2-Control_Break BAT-Switch_to_V_Mem 2-IO_Device_Control BAT-System_Request 2-Interrupt_Vector Crit_Error_Address 2-Load_Execute_Prgm Ctrl-Break_Address 2-Remove_Directory DIRECT_INPUT 2-Rename_File DIRECT_OUTPUT 2-Subpgrm_Rtn_Code Divide_by_Zero 2-TERM_Resident INDEF_FUNC 2-TERM_w_RtnCde INDEF_FUNC 3-Create_Temp_File INDEF_INSTR 3-Lock_Unlock_File INT_on_Overflow 3-PSP_Address Non-Maskable_INT AbsoluteDisk_Write One_Byte_Interrupt Absolute_Disk_Read RETURN_CODE B-Clock_Count STACK_PTR_CHG B-Control_to_BASIC SYNTAX_ERROR B-Format_FD_Track Single_Step B-Read_FD_Sectors TERMINATE_Resident B-Set_Clock_Count TERM_normally B-TERMINATE_REBOOT Terminate_Address B-Write_FD_Sectors XS_SGMT_CHG BAT-Alt_Disk_Reset XS_SGMT_OVRD The most important instructions to watch for are port operations, IN and OUT. When a program is using these, it is programming or interfacing directly with the hardware and bypassing the more compatible BIOS and DOS functions. There are three ways software uses hardware: directly, with BIOS, or with DOS functions. The tradeoff is speed vs. compatibility. The more DOS is used, the more compatible it is with various computers. But it is also slower, since the functions are more generic and have to handle a wider variety of input. Use of BIOS is faster, but much more hardware specific. Programming and going directly to the hardware is extremely fast, but completely hardware specific. The use of input and output ports is the most difficult to disassemble and understand. Start with the hardware the port is assigned to and go from there. The Difference Between MASTER*KEY Output and Microsoft's MASM 4.0: ------------------------------------------------------------------ TRANSLATING DISASSEMBLED FILES: ------------------------------- Microsoft's MASM 4.0 has strong type checking and is somewhat unforgiving to older source code programs. Some assembly language programs found in magazines and journals will just not assemble without a great deal of modification. Every effort has been made to have MASTER*KEY code as compatible as possible, but there are always exceptions. It is a good rule of thumb to avoid future trouble by making your source program assemble exactly like the original object code program before doing any major modification (when completely reassembling the file). *** CAUTION *** Although some object code is valid, and will execute flawlessly with the Intel architecture, when disassembled and reassembled, its not the same. And unfortunately, this is very common. MASTER*KEY will label potential problems: ADD AL,[BX+SI+00h] ;ASM_Syntax_Error ;00550 024000 is assembled and disassembled as (with a change and loss of code): ADD AL,[BX+SI] ;00550 0200 Several opcodes have synonyms and usually should be translated verbatim (take a hard look at the code, its probably data): ADD AL,AL ;00354 00C0 ;MASM Translation: 02C0 DB 02h,0C0h ADD Byte Ptr [BX+SI],01h ;004A7 820001 ;MASM Translation: 800001 DB 82h,00h,01h INC AX ;00AAD FFC0 ;MASM Translation: 40 DB 0FFh,0C0h The only way MASM can differentiate between NEAR and FAR returns is by including PROC FAR psuedo-ops in the source code. This will not work if NEAR and FAR returns are combined in the same object module. A lot of older programs have this problem. In DOS 1, a program could terminate with a FAR return to 0, with all other returns obviously being NEAR, since COM programs normally have only one segment. ; RET 0201h ;RET_Far:0201h ;00536 CA0102 ;MASM error 10: Syntax error DB 0CAh,01h,02h ; RET ;RET_Far ;00539 CB ;MASM error 10: Syntax error DB 0CBh H00536 PROC FAR ... RET 0201h ;RETURN_CODE ;00536 CA0102 RET ;00539 CB ... H00536 END PROC If 0Ah follows the Ascii-Adjust opcodes, just remove the operand. Anything other than 0Ah is a syntax error. ; AAM 0Ah ;00547 D40A ;MASM error 1: Extra characters on line AAM ;00547 D40A ; AAD 0Ah ;00549 D50A ;MASM error 1: Extra characters on line AAD ;00549 D50A ; AAM 00h ;00547 D400 ;MASM error 1: Extra characters on line DB 0D4h,00h ; AAD 00h ;00549 D500 ;MASM error 1: Extra characters on line DB 0D5h,00h Doubleword Jmps and Calls to a location outside of the current object module require an EXTRN pseudo-op before the ASSUME CS to define the external label. The label is prefixed with the code segment (CS:). When assembled, the LINK program will resolve the addresses if you have defined them in another source code module. For temporary fixes, the DB's are the best. If the label is not resolved before linking, the 9Ah CALL will be altered to 0CCh INT 3. Also the contents of the segment:offset bytes will be all zeros. ; CALL 00403h:00201h ; . . . . . . . . . ;004CF 9A01020304 ;MASM error 38: Left operand must have segment DB 9Ah,01h,02h,03h,04h ; JMP 00403h:00201h ;00574 EA01020304 ;MASM error 38: Left operand must have segment DB 0EAh,01h,02h,03h,04h EXTRN UNIQUE_LABEL:FAR ASSUME CS:CODE ; CALL 00403h:00201h ; . . . . . . . . . ;004CF 9A01020304 ; JMP 00403h:00201h ;00574 EA01020304 CALL CS:UNIQUE_LABEL ; . . . . . . . . . ;004CF 9A01020304 JMP CS:UNIQUE_LABEL ; . . . . . . . . . ;00574 EA01020304 The LOCK opcode is very seldom used (only for multiprocessing), and must be disassembled by hand if valid. ; LOCK ;0057E F0 ;MASM error 66: Must have opcode after prefix DB 0F0h .PA ASSEMBLY LANGUAGE REFERENCE: ---------------------------- SEGMENT REGISTERS: CS Code Segment DS Data Segment SS Stack Segment ES Extra Segment GENERAL REGISTERS: AX Accumulator AH - AL (High & Low Bytes BX Base BH - BL of Word Registers) CX Counter CH - CL DX Data DH - DL SP Stack Pointer (Stack Address) BP Base Pointer (Alternate Stack Address or Interior Stack Marker) SI Source Index (Implicit Address for String Ops) DI Destination Index (Implicit Address for String Ops) IP Instruction Pointer (Code Address) FLAGS - Status and Control Flags Register FLAGS: AF Auxiliary Carry (for BCD Arithmetic) CF Carry Flag DF Direction Flag (Strings) IF Interrupt Enable Flag OF Overflow Flag (CF and SF) PF Parity Flag SF Sign Flag TF Trap Flag (Single Step) ZF Zero Flag FLAGS REGISTER BIT PATTERN (XX = NOT USED): 15 8 0 XX XX XX XX OF DF IF TF SF ZF XX AF XX PF XX CF OPERAND SUMMARY: ---------------- MULTI-BYTE INSTRUCTIONS: Second Byte Bit Pattern: mod XXX r/m mod Displacement (immediate value alter index) 00 No DISP (except if mod = 00 and r/m = 110 then EA = Disp High:Disp Low) 01 DISP = Disp Low Sign-extended to 16 bits, No Disp High 10 DISP = Disp High:Disp Low 11 r/m is treated as a "reg" field r/m Operand Address 000 [BX + SI + DISP] ([expression] indicates the 001 [BX + DI + DISP] contents of the memory location 010 [BP + SI + DISP] pointed to by the expression 011 [BP + DI + DISP] rather than the location itself. 100 [SI + DISP] 101 [DI + DISP] 110 [BP + DISP] 111 [BX + DISP] DISP follows 2nd byte of instruction (before data if required). mod = 11, r/m "reg" field bit assignments: Word Operand Byte Operand 000 AX 000 AL 001 CX 001 CL 010 DX 010 DL 011 BX 011 BL 100 SP 100 AH 101 BP 101 CH 110 SI 110 DH 111 DI 111 BH SEGMENT OVERRIDE: Segment Override Prefix Bit Settings: 001 reg 110 Segment Override "reg" field bit assignments: 00 ES 01 CS 10 SS 11 DS Register Default with Segment Override Prefix IP CS:IP No Segment Override SP SS:SP No Segment Override BP SS:BP (BP + DS), ES, or CS SI or DI DS:XI ES, SS, or CS (No String Ops) SI DS:SI ES, SS, or CS DI ES:DI No Segment Override OPCODES IN ALPHABETICAL ORDER: Opcode Description ----------------------------------------- AAA Adjust Result of ASCII Addition AAD Adjust AX Register for Division AAM Adjust Result of BCD Multiplication AAS Adjust Result of ASCII Subtraction ADC Integer Add with Carry ADD Integer Add AND Logical And CALL Call a Subroutine CBW Convert Byte to Word CLC Clear Carry Flag Status CLD Clear Direction Flag CLI Clear Interrupt Enable Flag CMC Complement Carry Flag Status CMP Compare Two Operands CMPS Compare Memory with Memory (String) CWD Convert Word to Double Word DAA Adjust AL after BCD Addition DAS Adjust AL after BCD Subtraction DEC Decrement Register or Memory by One DIV Unsiged Division HLT Halt the Processor IDIV Signed Division IMUL Signed Multiplication IN Input Byte or Word from Port into AX INC Increment Register or Memory by One INT Software Interrupt INTO Interrupt on Overflow IRET Return from Interrupt Routine JA Jump if Above JB Jump if Below JBE Jump if Below or Equal JCXC Jump if CX = Zero JG Jump if Greater JGE Jump if Greater or Equal JL Jump if Less Than JLE Jump if Less Than or Equal JMP Jump Unconditionally JNB Jump if Not Below JNO Jump if Not Overflow JNS Jump if Not Sign JNZ Jump if Not Zero JO Jump if Overflow JPE Jump if Parity Even JPO Jump if Parity Odd JS Jump if Sign JZ Jump if Zero LAHF Load AH from Low-order Byte of Flags Register LDS Load Register and DS from Memory LEA Load Effective Address LES Load Register and ES from Memory LOCK Assert Bus Lock Signal LODS Load from Memory into Register (String) LOOP Loop (Decrement CX and Jump on Condition) LOOPNZ Loop while Not Zero LOOPZ Loop while Zero MOV Move MOVS Move Memory to Memory (String) MOVSW Move Word (String) MUL Unsigned Multiplication NEG Negate an Integer NOP No Operation (NULL Byte) NOT One's Complement of Register or Memory OR Logical Inclusive Or OUT Output Byte or Word to Port POP Read a Word from Top of Stack POPF Read Flags Register from Top of Stack PUSH Write a Word to Top of Stack PUSHF Copy Flags Register to Top of Stack RCL Rotate Left Through Carry RCR Rotate Right Through Carry REP Repeat Next String Instruction RET Return from Subroutine ROL Rotate Left ROR Rotate Right SAHF Store AH into Flags Register SAR Shift Arithmetic Right SBB Subtract with Borrow (Using Two's Complement) SCASB Scan Byte (String) SCASW Scan Word (String) SHL Logical Shift Left SHR Logical Shift Right STC Set Carry Flag STD Set Direction Flag STI Set Interrupt Enable Flag (Enable Interrupts) STOSB Store Byte (String) STOSW Store Word (String) SUB Subtraction (Using Two's Complement) TEST Logical Compare WAIT Wait While TEST Pin Not Asserted XCHG Swap Memory or Register with Register XLAT Table Lookup Translation XOR Logical Exclusive OR OPCODES IN HEX ORDER (variable opcodes have two bytes): 00 ADD 01 ADD 02 ADD 03 ADD 04 ADD 05 ADD 06 PUSH 07 POP 08 OR 09 OR 0A OR 0B OR 0C OR 0D OR 0E PUSH 0F CTS 10 ADC 11 ADC 12 ADC 13 ADC 14 ADC 15 ADC 16 PUSH 17 POP 18 SBB 19 SBB 1A SBB 1B SBB 1C SBB 1D SBB 1E PUSH 1F POP 20 AND 21 AND 22 AND 23 AND 24 AND 25 AND 26 ADD 27 DAA 28 SUB 29 SUB 2A SUB 2B SUB 2C SUB 2D ??? 2E ADD 2F DAS 30 XOR 31 XOR 32 XOR 33 XOR 34 XOR 35 XOR 36 ADD 37 AAA 38 CMP 39 CMP 3A CMP 3B CMP 3C CMP 3D CMP 3E ADD 3F AAS 40 INC 41 INC 42 INC 43 INC 44 INC 45 INC 46 INC 47 INC 48 DEC 49 DEC 4A DEC 4B DEC 4C DEC 4D DEC 4E DEC 4F DEC 50 PUSH 51 PUSH 52 PUSH 53 PUSH 54 PUSH 55 PUSH 56 PUSH 57 PUSH 58 POP 59 POP 5A POP 5B POP 5C POP 5D POP 5E POP 5F POP 60 ??? 61 ??? 62 ??? 63 ??? 64 ??? 65 ??? 66 ??? 67 ??? 68 ??? 69 ??? 6A ??? 6B ??? 6C ??? 6D ??? 6E ??? 6F ??? 70 JO 71 JNO 72 JB 73 JNB 74 JZ 75 JNZ 76 JBE 77 JA 78 JPO 79 JNS 7A JPE 7B JPO 7C JL 7D JGE 7E JLE 7F JG 8000 - 8007 ADD 8008 - 800F OR 8010 - 8017 ADC 8018 - 801F SBB 8020 - 8027 AND 8028 - 802F SUB 8030 - 8037 XOR 8038 - 803F CMP 8040 - 8047 ADD 8048 - 804F OR 8050 - 8057 ADC 8058 - 805F SBB 8060 - 8067 AND 8068 - 806F SUB 8070 - 8077 XOR 8078 - 807F CMP 8080 - 8087 ADD 8088 - 808F OR 8090 - 8097 ADC 8098 - 809F SBB 80A0 - 80A7 AND 80A8 - 80AF SUB 80B0 - 80B7 XOR 80B8 - 80BF CMP 80C0 - 80C7 ADD 80C8 - 80CF OR 80D0 - 80D7 ADC 80D8 - 80DF SBB 80E0 - 80E7 AND 80E8 - 80EF SUB 80F0 - 80F7 XOR 80F8 - 80FF CMP 8100 - 8107 ADD 8108 - 810F OR 8110 - 8117 ADC 8118 - 811F SBB 8120 - 8127 AND 8128 - 812F SUB 8130 - 8137 XOR 8138 - 813F CMP 8140 - 8147 ADD 8148 - 814F OR 8150 - 8157 ADC 8158 - 815F SBB 8160 - 8167 AND 8168 - 816F SUB 8170 - 8177 XOR 8178 - 817F CMP 8180 - 8187 ADD 8188 - 818F OR 8190 - 8197 ADC 8198 - 819F SBB 81A0 - 81A7 AND 81A8 - 81AF SUB 81B0 - 81B7 XOR 81B8 - 81BF CMP 81C0 - 81C7 ADD 81C8 - 81CF OR 81D0 - 81D7 ADC 81D8 - 81DF SBB 81E0 - 81E7 AND 81E8 - 81EF SUB 81F0 - 81F7 XOR 81F8 - 81FF CMP 8200 - 8207 ADD 8208 - 820F ??? 8210 - 8217 ADC 8218 - 821F SBB 8220 - 8227 ??? 8228 - 822F SUB 8230 - 8237 ??? 8238 - 823F CMP 8240 - 8247 ADD 8248 - 824F ??? 8250 - 8257 ADC 8258 - 825F SBB 8260 - 8267 ??? 8268 - 826F SUB 8270 - 8277 ??? 8278 - 827F CMP 8280 - 8287 ADD 8288 - 828F ??? 8290 - 8297 ADC 8298 - 829F SBB 82A0 - 82A7 ??? 82A8 - 82AF SUB 82B0 - 82B7 ??? 82B8 - 82BF CMP 82C0 - 82C7 ADD 82C8 - 82CF ??? 82D0 - 82D7 ADC 82D8 - 82DF SBB 82E0 - 82E7 ??? 82E8 - 82EF SUB 82F0 - 82F7 ??? 82F8 - 82FF CMP 8300 - 8307 ADD 8308 - 830F ??? 8310 - 8317 ADC 8318 - 831F SBB 8320 - 8327 ??? 8328 - 832F SUB 8330 - 8337 ??? 8338 - 833F CMP 8340 - 8347 ADD 8348 - 834F ??? 8350 - 8357 ADC 8358 - 835F SBB 8360 - 8367 ??? 8368 - 836F SUB 8370 - 8377 ??? 8378 - 837F CMP 8380 - 8387 ADD 8388 - 838F ??? 8390 - 8397 ADC 8398 - 839F SBB 83A0 - 83A7 ??? 83A8 - 83AF SUB 83B0 - 83B7 ??? 83B8 - 83BF CMP 83C0 - 83C7 ADD 83C8 - 83CF ??? 83D0 - 83D7 ADC 83D8 - 83DF SBB 83E0 - 83E7 ??? 83E8 - 83EF SUB 83F0 - 83F7 ??? 83F8 - 83FF CMP 84 TEST 85 TEST 86 XCHG 87 XCHG 88 MOV 89 MOV 8A MOV 8B MOV 8C MOV 8D LEA 8E MOV 8F POP 90 NOP 91 XCHG 92 XCHG 93 XCHG 94 XCHG 95 XCHG 96 XCHG 97 XCHG 98 CBW 99 CWD 9A CALL 9B WAIT 9C PUSHF 9D POPF 9E SAHF 9F LAHF A0 MOV A1 MOV A2 MOV A3 MOV A4 MOVSB A5 MOVSW A6 CMPSB A7 CMPSW A8 TEST A9 TEST AA STOSB AB STOSW AC LODSB AD LODSW AE SCASB AF SCASW B0 MOV B1 MOV B2 MOV B3 MOV B4 MOV B5 MOV B6 MOV B7 MOV B8 MOV B9 MOV BA MOV BB MOV BC MOV BD MOV BE MOV BF MOV C0 ??? C1 ??? C2 RET C3 RET C4 LES C5 LDS C6 MOV C7 MOV C8 ENTER C9 LEAVE CA RETF CB RETF CC INT CD INT CE INTO CF IRET D000 - D007 ROL D008 - D00F ROR D010 - D017 RCL D018 - D01F RCR D020 - D027 SHL D028 - D02F SHR D030 - D037 ??? D038 - D03F SAR D040 - D047 ROL D048 - D04F ROR D050 - D057 RCL D058 - D05F RCR D060 - D067 SHL D068 - D06F SHR D070 - D077 ??? D078 - D07F SAR D080 - D087 ROL D088 - D08F ROR D090 - D097 RCL D098 - D09F RCR D0A0 - D0A7 SHL D0A8 - D0AF SHR D0B0 - D0B7 ??? D0B8 - D0BF SAR D0C0 - D0C7 ROL D0C8 - D0CF ROR D0D0 - D0D7 RCL D0D8 - D0DF RCR D0E0 - D0E7 SHL D0E8 - D0EF SHR D0F0 - D0F7 ??? D0F8 - D0FF SAR D100 - D107 ROL D108 - D10F ROR D110 - D117 RCL D118 - D11F RCR D120 - D127 SHL D128 - D12F SHR D130 - D137 ??? D138 - D13F SAR D140 - D147 ROL D148 - D14F ROR D150 - D157 RCL D158 - D15F RCR D160 - D167 SHL D168 - D16F SHR D170 - D177 ??? D178 - D17F SAR D180 - D187 ROL D188 - D18F ROR D190 - D197 RCL D198 - D19F RCR D1A0 - D1A7 SHL D1A8 - D1AF SHR D1B0 - D1B7 ??? D1B8 - D1BF SAR D1C0 - D1C7 ROL D1C8 - D1CF ROR D1D1 - D1D7 RCL D1D8 - D1DF RCR D1E0 - D1E7 SHL D1E8 - D1EF SHR D1F0 - D1F7 ??? D1F8 - D1FF SAR D200 - D207 ROL D208 - D20F ROR D210 - D217 RCL D218 - D21F RCR D220 - D227 SHL D228 - D22F SHR D230 - D237 ??? D238 - D23F SAR D240 - D247 ROL D248 - D24F ROR D250 - D257 RCL D258 - D25F RCR D260 - D267 SHL D268 - D26F SHR D270 - D277 ??? D278 - D27F SAR D280 - D287 ROL D288 - D28F ROR D290 - D297 RCL D298 - D29F RCR D2A0 - D2A7 SHL D2A8 - D2AF SHR D2B0 - D2B7 ??? D2B8 - D2BF SAR D2C0 - D2C7 ROL D2C8 - D2CF ROR D2D2 - D2D7 RCL D2D8 - D2DF RCR D2E0 - D2E7 SHL D2E8 - D2EF SHR D2F0 - D2F7 ??? D2F8 - D2FF SAR D300 - D307 ROL D308 - D30F ROR D310 - D317 RCL D318 - D31F RCR D320 - D327 SHL D328 - D32F SHR D330 - D337 ??? D338 - D33F SAR D340 - D347 ROL D348 - D34F ROR D350 - D357 RCL D358 - D35F RCR D360 - D367 SHL D368 - D36F SHR D370 - D377 ??? D378 - D37F SAR D380 - D387 ROL D388 - D38F ROR D390 - D397 RCL D398 - D39F RCR D3A0 - D3A7 SHL D3A8 - D3AF SHR D3B0 - D3B7 ??? D3B8 - D3BF SAR D3C0 - D3C7 ROL D3C8 - D3CF ROR D3D3 - D3D7 RCL D3D8 - D3DF RCR D3E0 - D3E7 SHL D3E8 - D3EF SHR D3F0 - D3F7 ??? D3F8 - D0FF SAR D4 AAM D5 AAD D6 ??? D7 XLAT D8 ??? D9 ??? DA ??? DB ??? DC ??? DD ??? DE ??? DF ??? E0 LOOPNZ E1 LOOPZ E2 LOOP E3 JCXZ E4 IN E5 IN E6 OUT E7 OUT E8 CALL E9 JMP EA JMP EB JMP EC IN ED IN EE OUT EF OUT F0 LOCK F1 ??? F2 REPNZ F3 REPZ F4 HLT F5 CMC F6 TEST F7 TEST F8 CLC F9 STC FA CLI FB STI FC CLD FD STD FE00 - FE07 INC FE08 - FE0F DEC FE10 - FE17 ??? FE18 - FE1F ??? FE20 - FE27 ??? FE28 - FE2F ??? FE30 - FE37 ??? FE38 - FE3F ??? FE40 - FE47 INC FE48 - FE4F DEC FE50 - FE57 ??? FE58 - FE5F ??? FE60 - FE67 ??? FE68 - FE6F ??? FE70 - FE77 ??? FE78 - FE7F ??? FE80 - FE87 INC FE88 - FE8F DEC FE90 - FE97 ??? FE98 - FE9F ??? FEA0 - FEA7 ??? FEA8 - FEAF ??? FEB0 - FEB7 ??? FEB8 - FEBF ??? FEC0 - FEC7 INC FEC8 - FECF DEC FED0 - FED7 ??? FED8 - FEDF ??? FEE0 - FEE7 ??? FEE8 - FEEF ??? FEF0 - FEF7 ??? FEF8 - FEFF ??? FF00 - FF07 INC FF08 - FF0F DEC FF10 - FF17 CALL FF18 - FF1F ??? FF20 - FF27 JMP FF28 - FF2F ??? FF30 - FF37 PUSH FF38 - FF3F ??? FF40 - FF47 INC FF48 - FF4F DEC FF50 - FF57 CALL FF58 - FF5F ??? FF60 - FF67 JMP FF68 - FF6F ??? FF70 - FF77 PUSH FF78 - FF7F ??? FF80 - FF87 INC FF88 - FF8F DEC FF90 - FF97 CALL FF98 - FF9F ??? FFA0 - FFA7 JMP FFB0 - FFBF PUSH FFB8 - FFB7 ??? FFC0 - FFCF INC FFC8 - FFC7 DEC FFC8 - FFCF ??? FFD0 - FFD7 CALL FFD8 - FFDF ??? FFE0 - FFE7 JMP FFE8 - FFEF ??? FFF0 - FFF7 PUSH FFF8 - FFFF ??? .PA INPUT AND OUTPUT PORTS: ----------------------- Description PC/XT AT PCjr DMA Controller 1 000h-00Fh 000h-01Fh ... Interrupt Controller 1 020h-021h 020h-03Fh 020h-027h Timer 040h-043h 040h-05Fh 040h-047h PPI (Keyboard) 060h-063h ... 060h-067h AT Keyboard ... 060h-06Fh ... DMA Page Register 080h-083h 080h-09Fh ... NMI Mask Register 0Ah 070h-07Fh 0A0h-0A7h AT Interrupt Controller 2 ... 0A0h-0BFh ... PCjr Sound Generator ... ... 0C0h-0C7h AT DMA Controller 2 ... 0C0h-0DFh ... AT Clear/Reset 80287 ... 0F0h-0F1h ... AT 80287 Math Coprocessor ... 0F8h-0FFh ... Joystick 200h-20Fh 200h-207h 200h-207h PC/XT Expansion Unit 210h-217h ... ... AT Secondary Parallel Printer ... 278h-27Fh ... Primary Serial Port 3F8h-3FFh 3F8h-3FFh 2F8h-2FFh Secondary Serial Port 2F8h-2FFh 3F8h-3FFh ... Prototype Card 300h-31Fh 300h-31Fh ... Fixed Disk 320h-32Fh 1F0h-1F8h ... Primary Parallel Printer 378h-37Fh 378h-37Fh ... PC/XT SDLC (Mainframe Comm) 380h-38Fh ... ... AT Secondary Bisynch Comm ... 380h-38Fh ... AT Primary Bisynch Comm ... 3A0h-3AFh ... Monochrome Adapter/Printer 3B0h-3BFh 3B0h-3BFh ... Color Graphics Adapter 3D0h-3DFh 3D0h-3DFh ... Diskette Controller 3F0h-3F7h 3F0h-3F7h 0F0h-0FFh .PA INTERRUPT REFERENCE: -------------------- BIOS SERVICES & FUNCTION INTERRUPTS: INT 05h - BIOS Print Screen Send Screen Image to Printer INT 10h - BIOS Video Control AH = 00h Set Video Mode AH = 01h Set Cursor Size AH = 02h Set Cursor Position AH = 03h Read Cursor Position AH = 04h Read Light Pen Position AH = 05h Set Active Display Page AH = 05h AL = 80h Get Display Page Register AH = 05h AL = 81h Set CPU Display Page Register AH = 05h AL = 82h Set CRT Display Page Register AH = 05h AL = 83H Set CPU & CRT Display Page Register AH = 06h Scroll Window Up AH = 07h Scroll Window Down AH = 08h Read Character and Attribute AH = 09h Write Character and Attribute AH = 0Ah Write Character AH = 0Bh Set Color Palette AH = 0Ch Write Pixel Dot AH = 0Dh Read Pixel Dot AH = 0Eh Write Character as TTY AH = 0Fh Get Current Video Mode AH = 10h AL = 00h JR - Set One Palette Register AH = 10h AL = 01h JR - Set Border Register AH = 10h AL = 02h JR - Set All Palette Registers AH = 13h AT - Write Character String INT 11h - BIOS Equipment List Get List of Assigned Equipment INT 12h - BIOS Memory Available Get Available Memory Size in K-Bytes INT 13h - BIOS Disk Services AH = 00h Reset Disk System AH = 01h Get Disk Status AH = 02h Read Disk Sectors AH = 03h Write Disk Sectors AH = 04h Verify Disk Sectors AH = 05h Format Disk Track AH = 08h AT - Get Current Drive Parameters AH = 09h AT - Initialize Fixed-Disk Parameter Tables AH = 0Ah AT - Read Long AH = 0Bh AT - Write Long AH = 0Ch AT - Seek to Cylinder AH = 0Dh AT - Alternate Disk Reset AH = 10h AT - Test for Drive Ready AH = 11h AT - Recalibrate Drive AH = 14h AT - Controller Diagnostics AH = 15h AT - Get Disk Type AH = 16h AT - Change of Disk Status AH = 17h AT - Set Disk Type INT 14h - BIOS Serial Port Control AH = 00h Initialize Serial Port Parameters AH = 01h Send One Character AH = 02h Receive One Character AH = 03h Get Serial Port Status INT 15h - BIOS Cassette Control AH = 00h Turn Cassette Motor ON AH = 01h Turn Cassette Motor OFF AH = 02h Read Data Blocks AH = 03h Write Data Blocks INT 15h - BIOS Device Control AH = 80h AT - Device Open AH = 81h AT - Device Close AH = 82h AT - Device Program Termination AH = 83h AT - Event Wait INT 15h - BIOS Joystick Services AH = 84h AT - Joystick Support INT 15h - BIOS System Request AH = 85h AT - System Request Key Pressed INT 15h - BIOS Device Services AH = 86h AT - Wait AH = 87h AT - Move Memory Block INT 15h - BIOS Memory Management AH = 88h AT - Get Extended Memory Size AH = 89h AT - Switch to Virtual Memory INT 15h - BIOS Device Services AH = 90h AT - Device Busy Loop AH = 91h AT - Set Flag and Complex Interrupt INT 16h - BIOS Keyboard Control AH = 00h Read Next Keyboard Character AH = 01h Report whether Character Ready AH = 02h Get Shift Status AH = 03h AL = 00h JR - Reset Typematic AH = 03h AL = 01h JR - Increase Initial Delay AH = 03h AL = 02h JR - Increase Continuing Delays AH = 03h AL = 03h JR - Increase Both Delays AH = 03h AL = 04h JR - Turn Typematic OFF AH = 04h AL = 00h JR - Turn Click OFF AH = 04h AL = 01h JR - Turn Click ON INT 17h - BIOS Printer Control AH = 00h Send One Byte to Printer AH = 01h Initialize Printer AH = 02h Get Printer Status INT 18h - BIOS BASIC Switch Control to ROM BASIC INT 19h - BIOS Bootstrap Reset Computer INT 1Ah - BIOS Time Services AH = 00h Read Current Clock Count AH = 01h Set Current Clock Count AH = 02h AT - Read Real Time Clock AH = 03h AT - Set Real Time Clock AH = 04h AT - Read Date from Real Time Clock AH = 05h AT - Set Date in Real Time Clock AH = 06h AT - Set Alarm AH = 07h AT - Reset Alarm DOS INTERRUPT FUNCTIONS: 20h Program Terminate, Come to Normal Ending 21h Major DOS Function Call 22h Terminate Address 23h Break Address 24h Critical Error Handler Address 25h Absolute Disk Read 26h Absolute Disk Write 27h Terminate Program, but Stay Resident 2Fh Print Spool Control (DOS 3.0+ Versions Only) INT 21h - DOS FUNCTIONS AH = 00h Program Normal Terminate AH = 01h Keyboard Input with Echo AH = 02h Display Output AH = 03h Serial Port Input AH = 04h Serial Port Output AH = 05h Printer Output AH = 06h Direct Keyboard or Display I/O AH = 07h Direct Keyboard Input without Echo AH = 08h Keyboard Input without Echo AH = 09h Display String AH = 0Ah Buffered Keyboard Input AH = 0Bh Check Keyboard Input Status AH = 0Ch Clear Keyboard and Do Function AH = 0Dh Reset Disk AH = 0Eh Select Current Drive AH = 0Fh Open File AH = 10h Close File AH = 11h Search for First Matching Filename AH = 12h Search for Next Matching Filename AH = 13h Delete File AH = 14h Read Sequential File Record AH = 15h Write Sequential File Record AH = 16h Create File AH = 17h Rename File AH = 19h Report Current Drive AH = 20h Set Disk Transfer Area AH = 1Bh Get FAT Information, Current Drive AH = 1Ch Get FAT Information, Any Drive AH = 21h Read Random File Record AH = 22h Write Random File Record AH = 23h Get File Size AH = 24h Set Random Record Field AH = 25h Set Interrupt Vector AH = 26h Create Program Segment AH = 27h Read Random File Records AH = 28h Write Random File Records AH = 29h Parse Filename AH = 2Ah Get Date AH = 2Bh Set Date AH = 2Ch Get Time AH = 2Dh Set Time AH = 2Eh Set Disk Write Verification AH = 2Fh Get DTA Address AH = 30h Get DOS Version Number AH = 31h KEEP: Advanced Terminate but Stay Resident AH = 33h Get/Set Control Break AH = 35h Get Interrupt Vector AH = 36h Get Disk Free Space AH = 38h Get Country-Dependent Information AH = 39h MKDIR: Make Directory AH = 3Ah RMDIR: Remove Directory AH = 3Bh CHDIR: Change Current Directory AH = 3Ch CREAT: Create File AH = 3Dh Open File AH = 3Eh Close File Handle AH = 3Fh Read from File or Device AH = 40h Write to File or Device AH = 41h Delete File AH = 42h Move File Pointer AH = 43h CHMOD: Get/Set File Attributes AH = 44h IOCTL: I/O Control for Device Drivers AH = 45h DUP: Duplicate File Handle AH = 46h CDUP: Force Handle Duplication AH = 47h Get Current Directory AH = 48h Allocate Memory AH = 49h Free Allocated Memory Block AH = 4Ah SETBLOCK: Modify Allocated Memory Block AH = 4Bh EXEC: Load and Execute Subprogram AH = 4Ch Terminate Process AH = 4Dh Get Return Code of Subprogram AH = 4Eh FIND FIRST: Start Filename Search AH = 4Fh Continue Filename Search AH = 54h Get Verify State AH = 56h Rename File AH = 57h Get/Set File Date and Time AH = 58h Get/Set Memory Allocation Strategy DOS 3.0 SPECIFIC FUNCTIONS FOR INTERRUPT 21h AH = 59h Get Extended Error Code AH = 5Ah Create Temporary File AH = 5Bh Create New File AH = 5Ch Lock/Unlock File Access AH = 62h Get PSP Address .PA BIOS-DOS PARAMETERS AND MEMORY LOCATIONS: ----------------------------------------- BIOS Disk Status Code Byte Returned in AL: 01h = Bad Command 02h = Address Mark Not Found 03h = Write Attempted on Write-Protected Disk 04h = Sector Not Found 06h = Disk Removed 08h = DMA Overrun 09h = DMA Across 64K Boundary 0Ah Motor Startup Time 10h = Bad CRC 20h = Disk Controller Failed 40h = Seek Failed 80h = Disk Timed Out BIOS Serial Port Success/Failure Code Bit Settings Returned in AH: 0 = Data Ready 1 = Overrun Error 2 = Parity Error 3 = Framing Error 4 = Break Detected 5 = Transmission Buffer Register Empty 6 = Transmission Shift Register Empty 7 = Port Timed-Out BIOS Serial Port Modem Status Code Bit Settings Returned in AL: 0 = Delta Clear to Send 1 = Delta Set Ready 2 = Trailing Edge Ring Detected 3 = Change,receive Line Signal Detected 4 = Clear to Send 5 = Data Set Ready 6 = Ring Detected 7 = Receive Line Signal Detected BIOS Printer Success/Failure Status Code Bit Settings Returned in AH: 0 = Printer Timed Out 1 = Unused 2 = Unused 3 = I/O Error 4 = Selected 5 = Out of Paper 6 = Acknowledge 7 = Not Busy DOS DISK STATUS BYTE CODE BITS: 0 = Invalid Disk Command 1 = Disk Address Mark Not Found 2 = Disk Sector Not Found: Damaged or Not Formatted 3 = DMA Disk Error 4 = CRC (Cyclical Redundancy Check) Failed 5 = Disk Controller Chip Failed 6 = Seek to Track Failed 7 = Disk Timed-Out, Failed to Respond in Allotted Time DISK BASE TABLE (10 bytes): 00h Specify Byte 1: Step Rate Time, Head Unload Time 01h Specify Byte 2: Head Load Time, DMA Mode 02h Wait Time Until Diskette Drive Motor Turned OFF 03h Bytes per Sector: 0 = 128 2 = 512 3 = 1,024 04h Last Sector Number 05h Gap Length between Sectors for Read/Write 06h Data Length when Sector Length Not Specified 07h Gap Length between Sectors for Formatting 08h Data Value Stored in Formatted Sectors 09h Head Settle Time ALLOCATED MEMORY BLOCKS: F0000h Permanent ROM Area: ROM-BIOS, ROM BASIC, Boot Diagnostics E0000h Cartridge ROM Area (PC JR) D0000h Cartridge ROM Area (PC JR) C0000h BIOS Extensions (XT Disk) B0000h Conventional Display Memory (PC, XT, and AT) A0000h Display Memory Expansion 90000h User RAM, to 640K 80000h User RAM, to 576K 70000h User RAM, to 512K 60000h User RAM, to 448K 50000h User RAM, to 384K 40000h User RAM, to 320K 30000h User RAM, to 256K 20000h User RAM, to 192K 10000h User RAM, to 128K: Maximum Normally Allowed for PC JR 00000h User RAM, to 64K: Used by Operating System Software MAIN DOS INTERRUPT MEMORY LOCATIONS: 00h - 00000h Division by Zero 01h - 00004h Trace or Single-Step through Program (for Debugging) 02h - 00008h Non-Maskable Interrupt (Used by Hardware Debuggers) 03h - 0000Ch Set Break Points in Program (for Debugging) 04h - 00010h Arithmetic Overflow 05h - 00014h BIOS Print Screen Function Routine 08h - 00020h Hardware Clock Tick, for Real Time Interrupts 09h - 00024h Keyboard Input 0Dh - 00034h CRT Vertical Retrace, for Video Control 0Eh - 00038h Disk Attention Request 0Fh - 0113Ch Printer Control 10h - 00040h BIOS Video Display Functions 11h - 00044h BIOS Equipment List 12h - 00048h BIOS Memory Size 13h - 0004Ch BIOS Disk Functions 14h - 00050h BIOS Communications Functions 15h - 00054h BIOS Cassette Tape Functions 16h - 00058h BIOS Keyboard Functions 17h - 0005Ch BIOS Printer Functions 18h - 00060h ROM BASIC Language 19h - 00064h BIOS Computer Bootstrap (Reset) Routine 1Ah - 00068h BIOS Time and Date Functions 1Bh - 0006Ch BIOS Keyboard Control-Break 1Ch - 00070h Clock Tick 1Dh - 00074h Points to Table of Video Control Parameters 1Eh - 00078h Points to Disk Base Table 1Fh - 0007Ch Points to High Video Graphics Characters 20h - 00080h BIOS Program Terminate 21h - 00084h DOS Functions 22h - 00088h DOS Program-Terminate Custom Programmed Routine 23h - 0008Ch DOS Control-Break Custom Programmed Routine 24h - 00090h DOS Critical Error Custom Programmed Routine 25h - 00094h DOS Absolute Disk Read 26h - 00098h DOS Absolute Disk Write 27h - 0009Ch DOS Program Terminate, but Stay Resident 44h - 00110h Points to PC JR Low Video Graphics Characters 48h - 00120h PC JR Keyboard Translation 49h - 00124h Points to Translation Table for Keyboard Devices MEMORY LOCATIONS OF BIOS & DOS PARAMETERS: 00410h (2-Byte Word) Assigned Equipment List 00413h (2-Byte Word) Usable Memory Size in K, (BIOS Interrupt 12h Returns this Word) 0041Ah (2-Byte Word) Beginning of BIOS Keyboard Buffer 0041Ch (2-Byte Word) End of BIOS Keyboard Buffer 00441h (One Byte) Disk Status Code 00449h (One Byte) Current Video Mode 0044Ah (One 2-Byte Word) Screen Width in Text Columns 0044Eh (One 2-Byte Word) Screen Location Offset 00450h (Eight 2-Byte Words) Cursor Locations for the 8 Separate Video Pages. 00462h (One Byte) Current Display Page Number 00504h (One Byte) Mimic A Two-Disk System (for Systems with only One Disk Drive) 00510h (One 2-Byte Word) Default DS (Data Segment) Value .PA BIBLIOGRAPHY: ------------- (This is a suggested reference list and is by no means meant to be comprehensive. There are many more books available that are just as valuable). Crayne, Charles A. and Girard, Dian, THE SERIOUS ASSEMBLER. NY: Simon and Schuster Trade Publishing Group, 1985. A nice in- expensive reference. Dorner, Joe, ASSEMBLY LANGUAGE ROUTINES FOR THE IBM PC. NY: Brady Communications Company, Inc. (Simon & Schuster), 1985. A reference for writing assembly language subroutines for Basic programming. Duncan, Ray, ADVANCED MS DOS. Redmond, WA: Microsoft Press, 1986. A thorough DOS reference. IBM, DISK OPERATING SYSTEM (DOS 3.1) & MANUAL. Boca Raton, FL: International Business Machines Corporation, 1985. IBM, DISK OPERATING SYSTEM TECHNICAL REFERENCE MANUAL (DOS 3.1). Boca Raton, FL: International Business Machines Corporation, 1985. INTEL, 8086/8088/8087/80186/80188 PROGRAMMER'S POCKET REFERENCE GUIDE. Santa Clara, CA: Intel Corporation, 1982. Kamin, Jonathan, MS DOS POWER USER'S GUIDE. Berkeley, CA: Sybex Inc., 1986. A good batch file programming reference. Lafore, Robert, ASSEMBLY LANGUAGE PRIMER FOR THE IBM PC & XT. NY: The Waite Group (New American Library), 1984. An excellent tutorial on 8086 assembly language programming. Microsoft, MICROSOFT MACRO ASSEMBLER & MANUAL. Bellevue, WA: Microsoft Corporation, 1984. Morgan, Christopher L., BLUEBOOK OF ASSEMBLY ROUTINES FOR THE IBM PC & XT. NY: The Waite Group (New American Library), 1984. A reference of example routines in 8086 assembly language. Norton, Peter, THE PETER NORTON PROGRAMMER'S GUIDE TO THE IBM PC. Bellevue, WA: Microsoft Press, 1985. An excellent reference to DOS and ROM BIOS functions and interrupts. Norton, Peter, INSIDE THE IBM PC. NY: Brady Communications Company, Inc. (Simon & Schuster), 1985. Systems hardware/software reference.