DR DOS 9.0 USER GUIDE ========== Copyright (c) 2022-2026 Whitehorn Ltd. Co. All rights reserved. DR DOS is a registered trademark of Whitehorn Ltd. Co. WHITEHORN LTD. CO. 3963 S Highway 97 #214 Sand Springs, OK 74063 DISCLAIMER Whitehorn Ltd. Co. provides this publication "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of merchantability or fitness for a particular purpose. This publication may include technical inaccuracies or typographical errors. Changes are periodically made to the information herein. No part of this publication may be reproduced without the prior written permission of Whitehorn Ltd. Co. Last Modified: July 2026 =============================================================================== TABLE OF CONTENTS =============================================================================== Chapter 1 ......................................... Installing DR DOS Chapter 2 ......................................... Getting Started Chapter 3 ......................................... Working with Files Chapter 4 ......................................... Working with Directories Chapter 5 ......................................... Running Programs Chapter 6 ......................................... Advanced Features Chapter 7 ......................................... Command Reference Appendix A ........................................ Error Messages Appendix B ........................................ Batch Programming Guide Appendix C ........................................ Reporting Bugs and Issues Glossary =============================================================================== CHAPTER 1: INSTALLING DR DOS =============================================================================== SYSTEM REQUIREMENTS DR DOS 9.0 requires the following hardware: Processor Intel 386 or compatible Memory 2 MB RAM (minimum) Display VGA-compatible display adapter Storage FAT12 or FAT16 hard disk partition BIOS LBA or CHS disk addressing BETA SOFTWARE NOTICE DR DOS 9.0 is currently in beta testing. This means you may encounter bugs, crashes, system freezes, filesystem corruption, or compatibility issues during use. IMPORTANT PRECAUTIONS: - Back up all important data before installation - Do not use DR DOS 9.0 on production systems - Test in a virtual machine or on non-critical hardware - Be prepared for potential data loss Your participation in beta testing helps us identify and fix issues. Please report any problems you encounter (see "Reporting Bugs and Issues" section). SUPPORTED STORAGE DR DOS 9.0 supports FAT12 and FAT16 partitions on hard disks and floppy drives: Supported: FAT12 and FAT16 hard disk partitions FAT12 floppy disks (3.5-inch, 720K and 1.44MB) Booting from hard disk or 1.44MB floppy disk LBA disk addressing CHS disk addressing Drive letters: A: (floppy drive, auto-detected at boot) B: (floppy alias; shares physical drive with A: on single-floppy systems) C: (first hard disk partition) D:-R: (additional hard disk partitions, auto-detected; includes primary partitions and logical drives in extended partitions) AVAILABLE LANGUAGES DR DOS 9.0 is available in the following languages: English (en) All system messages, boot text, and error messages in English German (de) Alle Systemmeldungen, Starttexte und Fehlermeldungen auf Deutsch Each release includes separate disk images for each language. The two-letter language code appears in the image filename: boot16_en.img.7z English hard disk image boot16_de.img.7z German hard disk image floppy144_en.img.7z English floppy disk image floppy144_de.img.7z German floppy disk image The images are identical in functionality; only the language of system messages differs. This manual uses the English (en) filenames in all examples. Substitute _de for _en if you prefer the German version. INSTALLATION PROCEDURE DR DOS 9.0 is available in two formats: boot16_xx.img.7z Pre-configured bootable hard disk image floppy144_xx.img.7z Bootable 1.44MB floppy disk image with installer where xx is the language code (en for English, de for German). Choose the method that best fits your hardware or emulator setup. METHOD 1: HARD DISK IMAGE (RECOMMENDED) The hard disk image is a ready-to-use bootable disk with DR DOS pre-installed. This is the fastest way to get started. Step 1: Obtain the disk image Download boot16_en.img.7z from the DR DOS website (https://www.dr-dos.com). Step 2: Extract the disk image Use 7-Zip to extract the image file: 7z x boot16_en.img.7z This creates boot16_en.img (approximately 120 MB). Step 3: Write the image to bootable media Use dd or a similar disk imaging tool to write the image to a CompactFlash card, USB drive, or virtual disk: dd if=boot16_en.img of=/dev/sdX bs=4M status=progress Replace /dev/sdX with your target device identifier. IMPORTANT: Ensure you specify the correct device. Writing to the wrong device will destroy data on that device. Step 4: Boot from the media Configure your computer or emulator to boot from the media you created. DR DOS will load automatically and present the command prompt. METHOD 2: FLOPPY DISK INSTALLATION The floppy image is a bootable 1.44MB 3.5-inch floppy disk that includes an installer for setting up DR DOS on a hard disk. Use this method when installing DR DOS onto a new or empty hard disk, or on real hardware with a floppy drive. Step 1: Obtain the floppy image Download floppy144_en.img.7z from the DR DOS website (https://www.dr-dos.com). Step 2: Extract the floppy image Use 7-Zip to extract the image file: 7z x floppy144_en.img.7z This creates floppy144_en.img (1.44 MB). Step 3: Write the image to a floppy disk or virtual floppy For a physical floppy disk: dd if=floppy144_en.img of=/dev/fdX bs=512 For a virtual machine, attach floppy144_en.img as a floppy disk drive. Step 4: Boot from the floppy disk Configure your computer or emulator to boot from the floppy drive. DR DOS will load and present the command prompt. Step 5: Partition the hard disk (if needed) If your hard disk does not already have a DOS partition, use FDISK to create one: A:\>FDISK Follow the on-screen prompts to create a primary DOS partition. Reboot after partitioning. Step 6: Run the installer At the A:\> prompt, run the installation utility: A:\>INSTALL INSTALL will: - Format drive C: and transfer system files - Copy all DOS utilities to C:\DOS\ - Copy EMM386.SYS to C:\ WARNING: INSTALL formats drive C:, destroying all existing data. Step 7: Reboot from the hard disk Remove the floppy disk and reboot. DR DOS will start from drive C:. RUNNING IN QEMU QEMU is a popular open-source emulator for testing DR DOS. Hard disk image: qemu-system-i386 -m 16m -drive file=boot16_en.img,format=raw,if=ide -cpu 486 Floppy installation (with an empty 128MB hard disk): qemu-img create -f raw hdd.img 128M qemu-system-i386 -m 16m -cpu 486 \ -drive file=hdd.img,format=raw,if=ide \ -drive file=floppy144_en.img,format=raw,if=floppy,index=0 \ -boot a WHAT'S INCLUDED The hard disk image (boot16_en.img) includes: - DR DOS 9.0 kernel and boot loader - COMMAND.COM (command interpreter) - Standard DOS utilities in C:\DOS\ - FAT16 filesystem pre-configured on drive C: The floppy disk image (floppy144_en.img) includes: - DR DOS 9.0 kernel and boot loader - COMMAND.COM (command interpreter) - Standard DOS utilities in DOS\ - INSTALL.BAT installation utility - EMM386.SYS expanded memory manager - ANSI.SYS console driver (ANSI escape sequence support) KNOWN LIMITATIONS Be aware of the following limitations in this release: Scripting - FOR loops are not supported in batch files Advanced Features - Input redirection (<) is not supported - Append redirection (>>) is not supported =============================================================================== CHAPTER 2: GETTING STARTED =============================================================================== WHAT IS DR DOS? DR DOS 9.0 is a disk operating system. It provides the essential services that allow you to run programs, manage files, and organize your hard disk. When you turn on your computer, DR DOS loads automatically and presents you with a command prompt. THE COMMAND PROMPT After DR DOS starts, you will see a prompt that looks like this: C:\> This prompt tells you: - The current drive (C:) - The current directory (\, the root) - That the system is ready for your command (>) You type commands at this prompt and press ENTER to execute them. While typing a command, you can use Backspace to erase the previous character. Press ENTER to execute the command, or Ctrl-C to cancel the current line and return to the prompt. DRIVES AND DRIVE LETTERS DR DOS identifies disk drives with letters: A: Floppy drive (3.5-inch, auto-detected at boot) B: Floppy drive alias (shares physical drive with A: on single-floppy systems; detected automatically via BIOS) C: First hard disk partition D:-R: Additional hard disk partitions (auto-detected at boot if present) If no floppy drive is present, or if no floppy disk is inserted when the system starts, A: and B: will not be available. On single-floppy systems, A: and B: refer to the same physical drive. DR DOS automatically detects when a floppy disk has been swapped; no command or reboot is required after inserting a different disk. The current directory is preserved across disk changes. To switch to a different drive, type the drive letter followed by a colon and press ENTER: C:\>A: A:\> C:\>D: D:\> The prompt changes to show your new current drive. CONVENTIONS USED IN THIS MANUAL Commands are shown in UPPERCASE: DIR COPY Parameters you supply are shown in lowercase: COPY source destination Optional parameters are shown in brackets: DIR [drive:] Literal characters you must type exactly are shown as-is: C:\DOS\ BUILT-IN VS EXTERNAL COMMANDS DR DOS commands fall into two categories: BUILT-IN COMMANDS are part of COMMAND.COM itself and are always available, even if no external files are present: CD Change directory (also: CHDIR) COPY Copy files DEL Delete files (also: ERASE) ECHO Display messages or control command echoing EXIT Exit command interpreter MD Create directory (also: MKDIR) RD Remove directory (also: RMDIR) REN Rename files and directories (also: RENAME) SET Display or modify environment variables VER Display version EXTERNAL COMMANDS are separate .COM program files that must be present in the current directory or in C:\DOS\ to work: BATCH Batch file interpreter (invoked automatically for .BAT files) CLS Clear screen DATE Display or set system date DIR Directory listing EDIT Full-screen text editor FDISK Partition hard disks FORMAT Format and create filesystems on disk partitions HEXDUMP Display hexadecimal file dump JMP Execute code at memory address MEM Display memory information MORE Page through text output MOUSE PS/2 mouse driver (TSR) MOVE Move files PEEK Read byte from memory POKE Write byte to memory REBOOT Restart system TYPE Display file contents If you receive "Bad command or file name" for an external command, verify that the corresponding .COM file exists in C:\DOS\ or the current directory. =============================================================================== CHAPTER 3: WORKING WITH FILES =============================================================================== FILE NAMES Every file has a name consisting of up to 8 characters, optionally followed by a period and an extension of up to 3 characters: LETTER.TXT REPORT.DOC COMMAND.COM CONFIG.SYS The extension often indicates the type of file: .COM Executable program .EXE Executable program .TXT Text file .SYS System configuration file File names cannot contain these characters: < > : " | ? * / \ WILDCARD CHARACTERS Two special characters help you work with groups of files: * Matches any sequence of characters ? Matches any single character Examples: *.TXT All files with .TXT extension REPORT.* All files named REPORT with any extension FILE?.DOC FILE1.DOC, FILE2.DOC, FILEA.DOC, etc. VIEWING FILES: DIR The DIR command displays a list of files in a directory. Syntax: DIR [filespec] [/W] Switches: /W Wide format (5 columns, filenames only) Examples: DIR List all files in current directory DIR *.TXT List all .TXT files DIR /W List files in wide format DIR D: List all files on drive D: DIR displays the volume label and serial number (if present), followed by the file name, size in bytes, date (MM-DD-YY), and time (H:MMa/p) for each file, followed by the total number of files found. With the /W switch, DIR displays only file names in a compact 5-column format without size, date, or time information. VIEWING FILE CONTENTS: TYPE The TYPE command displays the contents of a text file on screen. Syntax: TYPE filename Example: TYPE README.TXT NOTE: TYPE is an external command. The file TYPE.COM must be in the current directory or in the C:\DOS\ directory for this command to work. TIP: For long files, use TYPE filename | MORE to page through the output one screen at a time. WARNING: Using TYPE on a program file (.COM or .EXE) will display meaningless characters and may cause your screen to behave erratically. Only use TYPE on text files. COPYING FILES: COPY The COPY command makes a duplicate of a file. Syntax: COPY source destination Examples: COPY LETTER.TXT LETTER.BAK COPY D:DATA.TXT C:\DOCS\DATA.TXT COPY REPORT.DOC D: When copying to a drive without specifying a filename, the original name is preserved. NOTE: The COPY command copies one file at a time. Wildcard characters are not supported in this version. DELETING FILES: DEL The DEL command deletes one or more files from your disk. Syntax: DEL filename ERASE filename Examples: DEL LETTER.TXT ERASE REPORT.DOC DEL *.BAK DEL and ERASE are identical commands. CREATING DIRECTORIES: MD The MD command creates a new directory. Syntax: MD dirname MKDIR dirname Examples: MD DOCS MKDIR BACKUPS Notes: - MD and MKDIR are identical commands. - The parent directory must already exist. - If a directory with the same name already exists, MD will return an error instead of creating a duplicate entry. - Wildcard characters are not supported. RENAMING FILES AND DIRECTORIES: REN The REN command renames an existing file or directory. It can also move a file or directory to a different location on the same drive. Syntax: REN oldname newname RENAME oldname newname Examples: REN OLD.TXT NEW.TXT RENAME LETTER.DOC LETTER.BAK REN DOCS ARCHIVE REN \WORK\FILE.TXT \DONE\FILE.TXT REN and RENAME are identical commands. MOVING FILES: MOVE The MOVE command relocates a file from one location to another. Unlike COPY, the original file is removed after a successful move. Syntax: MOVE source destination Examples: MOVE OLDFILE.TXT NEWFILE.TXT MOVE C:\DOCS\LETTER.TXT D:\BACKUP\ When moving to a directory, if the destination already exists, MOVE will ask whether to overwrite it. NOTE: MOVE is an external command. The file MOVE.COM must be in the current directory or in the C:\DOS\ directory. =============================================================================== CHAPTER 4: WORKING WITH DIRECTORIES =============================================================================== WHAT IS A DIRECTORY? A directory is a container for files. Directories can contain other directories, creating a tree-like structure for organizing your files. Every disk has a root directory, indicated by a single backslash (\). All other directories branch from the root. Example directory structure: C:\ \DOS\ COMMAND.COM TYPE.COM MOVE.COM \DOCS\ LETTER.TXT REPORT.DOC \PROGRAMS\ EDITOR.EXE PATHS A path describes the location of a file or directory. It consists of an optional drive letter, followed by a series of directory names separated by backslashes, ending with a filename: C:\DOCS\LETTER.TXT This path indicates: - Drive C: - In the DOCS directory - The file LETTER.TXT CHANGING DIRECTORIES: CD The CD (Change Directory) command changes your current directory or displays the current directory path. Syntax: CD [path] Examples: CD Display current directory CD \ Go to root directory CD \DOCS Go to DOCS directory CD .. Go to parent directory CD SUBDIR Go to subdirectory named SUBDIR The CD command can also be typed as CHDIR. Spaces are optional when using .., \, or / as the path (CD.. and CD\ also work). =============================================================================== CHAPTER 5: RUNNING PROGRAMS =============================================================================== EXECUTABLE FILES Programs are stored as executable files with .COM or .EXE extensions. To run a program, type its name (with or without the extension) and press ENTER: EDIT EDIT.COM MYPROG.EXE DR DOS searches for the program in this order: 1. Current directory, with .COM extension 2. Current directory, with .EXE extension 3. C:\DOS\ directory, with .COM extension 4. C:\DOS\ directory, with .EXE extension 5. Current directory, with .BAT extension 6. C:\DOS\ directory, with .BAT extension Batch files (.BAT) are text files containing a series of commands. When a .BAT file is found, DR DOS automatically invokes the BATCH.COM interpreter to execute it. See Chapter 6 for details on batch files. NOTE: The search path is fixed to the current directory and C:\DOS\. Unlike some other DOS systems, there is no configurable PATH environment variable. PASSING PARAMETERS TO PROGRAMS Most programs accept parameters that control their behavior. Type the parameters after the program name, separated by spaces: TYPE README.TXT COPY FILE1.TXT FILE2.TXT MOVE /? Consult the documentation for each program to learn its parameters. Most external commands accept /? or /H to display a brief help screen describing their syntax and switches: FORMAT /? MEM /H EXITING PROGRAMS Most programs return to the DOS prompt when they finish. Some programs require you to type a command like EXIT or QUIT, or press a key combination. Consult each program's documentation. THE EXIT COMMAND The EXIT command terminates the command interpreter. On most systems, this will return you to the program that started COMMAND.COM. If you type EXIT at the main DOS prompt (after booting), the system may restart or halt. Use EXIT only when instructed by a program. =============================================================================== CHAPTER 6: ADVANCED FEATURES =============================================================================== OUTPUT REDIRECTION DR DOS supports redirecting a command's output to a file using the greater-than symbol (>). Syntax: command > filename The output that would normally appear on screen is instead written to the specified file. If the file already exists, it will be overwritten without warning. Examples: DIR > FILELIST.TXT DIR *.COM > PROGRAMS.TXT MEM > MEMORY.TXT This feature is useful for: - Saving directory listings to review later - Capturing program output for documentation - Creating text files from command output NOTES: - Only output redirection (>) is supported - Input redirection (<) is not supported PIPING OUTPUT TO MORE DR DOS supports piping command output to the MORE utility using the pipe symbol (|). Syntax: command | MORE The output of the command is displayed one page at a time, allowing you to read through long output without it scrolling off the screen. Examples: DIR | MORE Page through directory listing TYPE README.TXT | MORE Page through file contents MEM /A | MORE Page through memory information Controls when viewing output: Space Display next page (23 lines) Enter Display next line Q or Esc Quit NOTES: - Currently only piping to MORE is supported - Multiple pipes (cmd | cmd | cmd) are not supported BATCH FILES DR DOS supports batch file scripting. A batch file is a text file with a .BAT extension that contains a series of commands to be executed in sequence. Batch files are useful for automating repetitive tasks. Creating a Batch File: Use the EDIT command or any text editor to create a file with a .BAT extension. Each line contains one command: Example: CLEANUP.BAT ---------------------- @ECHO OFF ECHO Cleaning up temporary files... DEL *.TMP DEL *.BAK ECHO Done. Running a Batch File: Type the batch file name (with or without the .BAT extension): C:\>CLEANUP C:\>CLEANUP.BAT Supported Batch Commands: Flow Control: REM comment Comment line (ignored) ECHO message Display message on screen ECHO OFF/ON Disable/enable command echoing ECHO. Display a blank line @command Execute command without echoing it PAUSE Wait for a keypress GOTO label Jump to a label GOTO :EOF Exit the current batch file :label Define a label CALL filename [args] Execute another batch file and return Conditionals: IF EXIST file cmd Execute cmd if file exists IF NOT EXIST file cmd Execute cmd if file does not exist IF ERRORLEVEL n cmd Execute cmd if last exit code >= n IF NOT ERRORLEVEL n cmd Execute cmd if last exit code < n IF "s1"=="s2" cmd Execute cmd if strings are equal IF NOT "s1"=="s2" cmd Execute cmd if strings differ File Operations: COPY src dest Copy a file DEL file Delete a file (also: ERASE) REN old new Rename a file (also: RENAME) MD dirname Create a directory (also: MKDIR) RD dirname Remove an empty directory (also: RMDIR) CD path Change current directory (also: CHDIR) Variables: %0 - %9 Command-line parameters %VARNAME% Environment variable expansion SHIFT Shift parameters left (%1->%0, %2->%1, ...) SET Display all environment variables SET prefix Display variables starting with prefix SET VAR=value Set environment variable Redirection: command > file Redirect output to a file Parameter Substitution: Batch files can accept parameters. Use %0 through %9 to reference them: %0 The batch file name itself %1 First parameter %2 Second parameter ... %9 Ninth parameter Use SHIFT to access more than 9 parameters. Each SHIFT moves all parameters down by one position (%2 becomes %1, %3 becomes %2, etc.). Example batch file (BACKUP.BAT): @ECHO OFF ECHO Backing up %1 to %2... COPY %1 %2 ECHO Backup complete. Running: BACKUP.BAT README.TXT D:\BACKUP\README.TXT Environment Variables: Access environment variables using %VARNAME% syntax: ECHO The COMSPEC is: %COMSPEC% IF "%MYVAR%"=="" ECHO MYVAR not set Use SET to display, search, or modify environment variables: SET Display all variables SET P Display variables starting with P SET VAR=value Set VAR to value SET VAR= Remove VAR from the environment Conditional Execution: The IF command allows conditional execution: IF EXIST CONFIG.SYS ECHO Config file found IF NOT EXIST TEMP MD TEMP IF "%1"=="" ECHO No parameter provided IF ERRORLEVEL 1 ECHO Program returned an error ERRORLEVEL tests the exit code of the previous program. The condition is true if the exit code is greater than or equal to the specified value. Test higher values first: PROGRAM.EXE IF ERRORLEVEL 2 GOTO FATAL IF ERRORLEVEL 1 GOTO WARNING ECHO Success! Labels and GOTO: Use labels and GOTO for flow control: @ECHO OFF IF "%1"=="" GOTO USAGE ECHO Processing %1... GOTO END :USAGE ECHO Usage: PROCESS filename :END Use GOTO :EOF to exit the batch file immediately without requiring an :END label. Calling Other Batch Files: Use CALL to execute another batch file and return to continue: @ECHO OFF ECHO Starting installation... CALL SETUP.BAT ECHO Setup complete, running configuration... CALL CONFIG.BAT ECHO All done! Without CALL, executing a batch file transfers control permanently and does not return to the calling script. NOTES: - Batch file support requires BATCH.COM in C:\DOS\ - Use SET to view or modify environment variables - Use SHIFT to process more than 9 parameters AUTOEXEC.BAT - Automatic Startup Script DR DOS automatically executes C:\AUTOEXEC.BAT at boot time if it exists. This batch file runs once during system startup, before the first command prompt appears. If C:\AUTOEXEC.BAT does not exist, the system boots directly to the command prompt with no error message. Common uses for AUTOEXEC.BAT: - Setting environment variables (SET TEMP=C:\TEMP) - Loading mouse drivers (MOUSE) - Displaying a welcome message - Launching a menu or application Example AUTOEXEC.BAT: @ECHO OFF SET TEMP=C:\TEMP ECHO Loading DR DOS... MOUSE ECHO. ECHO Welcome to DR DOS 9.0 ECHO. CONFIG.SYS - System Configuration DR DOS processes C:\CONFIG.SYS at boot time if it exists. This file configures system settings and loads device drivers before the command prompt appears. If C:\CONFIG.SYS does not exist, the system boots with default settings. Creating CONFIG.SYS: Use the EDIT command to create C:\CONFIG.SYS. Each line contains one directive: Example: CONFIG.SYS ---------------------- DEVICE=ANSI.SYS DEVICE=C:\EMM386.SYS Supported Directives: DEVICE=path Load a device driver from the specified path Example: DEVICE=C:\EMM386.SYS The DEVICE directive loads a device driver during boot. Both flat binary (.SYS) and executable (.EXE) driver formats are supported; DR DOS detects the format automatically. The driver remains resident in memory and provides services to the system and applications. DEVICEHIGH=path Load a device driver (accepted for compatibility) Example: DEVICEHIGH=C:\DRIVERS\MOUSE.SYS Accepted for compatibility with CONFIG.SYS files written for other DOS systems. In this release, DEVICEHIGH loads the driver into conventional memory, exactly as DEVICE= does; loading drivers into upper memory blocks (UMBs) is not yet implemented. DOS=[HIGH|LOW][,UMB|,NOUMB] Control DOS memory configuration Example: DOS=HIGH,UMB Controls DOS memory placement and upper memory block (UMB) availability. HIGH loads DOS into the High Memory Area (HMA), which is the default. LOW loads DOS into conventional memory. UMB makes upper memory blocks available to programs; NOUMB (or omitting the UMB option) keeps UMBs unavailable. When UMB is specified, programs can use the UMB allocation strategies (0x40, 0x80) via INT 21h AH=58h. FILES=N Set the number of available file handles Example: FILES=20 Sets the maximum number of simultaneously open file handles. Default is 8. Valid range is 8 to 36. Values outside this range are clamped to the nearest limit. SHELL=path [args] Specify an alternate command interpreter Example: SHELL=C:\DOS\COMMAND.COM /E:512 Loads the specified program as the command interpreter instead of the default COMMAND.COM. The filename is extracted from the path and must be in 8.3 format. The /E:nnn switch sets the size of the master environment in bytes, where nnn is 160 to 32768. This reserves room for environment variables to grow. If /E: is omitted or its value is out of range, the default 256-byte environment is used. LASTDRIVE=X Set the highest valid drive letter Example: LASTDRIVE=F Controls the highest drive letter recognized by the system. Default is Z. Setting a lower value limits the range of valid drive letters (e.g., LASTDRIVE=F allows drives A: through F:). BREAK=ON|OFF Enable or disable extended Ctrl-C checking Example: BREAK=ON When set to ON, DR DOS checks for Ctrl-C before every DOS call, not just during character I/O operations. This makes long-running operations more responsive to Ctrl-C. Default is OFF. INSTALL=path [args] Load and run a program at boot Example: INSTALL=C:\DOS\MOUSE.COM Loads and executes the specified program during boot, before COMMAND.COM starts. Useful for loading terminate-and-stay-resident (TSR) utilities. Any text after the program path is passed to it as command-line arguments. NUMLOCK=ON|OFF Set the NumLock keyboard state at boot Example: NUMLOCK=OFF Turns the NumLock key on or off during boot and updates the keyboard LED to match. COUNTRY=nnn[,[cp]] Set the country code and code page Example: COUNTRY=049,850 Sets the country code (nnn) and optional code page (cp) reported by INT 21h AH=38h (Get Country Information). Note: in this release only the country-code and code-page numbers change; the locale formatting data (date, time, currency, and separator characters) remains at United States defaults. REM comment Comment line Example: REM This line is ignored A CONFIG.SYS comment. The entire line is ignored, allowing you to annotate your configuration. BUFFERS=N Set the number of disk buffers (reserved) STACKS=N,S Set interrupt stack parameters (reserved) FCBS=N Set the number of FCB handles (reserved) SWITCHES=/x Set startup switches (reserved) These directives are recognized but have no effect in this release. They are accepted for compatibility with CONFIG.SYS files written for other DOS systems. DEVICE NAMES DR DOS recognizes several special device names that can be used in place of filenames. These names are reserved and cannot be used for regular files. CON Console (keyboard input, screen output) NUL Null device (discards all output, returns empty on input) AUX Auxiliary device (typically COM1) PRN Printer (typically LPT1) The NUL Device: The NUL device is particularly useful for discarding unwanted output: DIR > NUL Run DIR but discard all output COPY FILE.TXT NUL Test if file can be read (output discarded) command > NUL Suppress output from any command In batch files, use IF EXIST NUL to test if device names are available (this always succeeds since NUL is a built-in device): IF EXIST NUL ECHO Device support available Device names are recognized in any directory context. You cannot create a file named NUL, CON, AUX, or PRN. EXPANDED MEMORY (EMS) NOTE: EMM386.SYS is currently experimental and under active development. While it provides EMS and VCPI support for many common applications, some programs may experience compatibility issues. Please report any problems to bugs@dr-dos.com. DR DOS includes EMM386.SYS, an expanded memory manager that provides access to memory beyond the 640KB conventional memory limit. What is EMS? Expanded Memory Specification (EMS) is a standard for accessing additional memory on DOS systems. EMS memory is accessed through a 64KB "page frame" window in the upper memory area, with 16KB pages that can be mapped in and out as needed. DR DOS EMS Features: - EMS 4.0 support - Page frame at segment D000h (standard location) - Four 16KB physical pages (64KB page frame) - Up to 32MB of expanded memory (limited by available XMS) - 255 EMS handles maximum - Uses XMS memory as backing store Enabling EMS - EMM386.SYS: EMS requires loading the EMM386.SYS driver via CONFIG.SYS: DEVICE=C:\EMM386.SYS Create or edit C:\CONFIG.SYS to include this line, then reboot. EMM386.SYS provides: - EMS 4.0 support - VCPI support for DOS extenders and protected-mode programs - Uses XMS memory as backing store for EMS pages Without EMM386.SYS loaded, EMS is not available and programs that require expanded memory will report no EMS present. Checking EMS Availability: Use MEM to see expanded memory status: C:\>MEM /M The memory map (/M switch) shows EMS page frame regions. Extended memory shown in the basic MEM summary reflects XMS, which serves as the backing store for EMS pages. Programs that Support EMS: Many DOS applications can use EMS for additional memory: - Spreadsheets (Lotus 1-2-3, Quattro Pro) - Databases (dBASE, Paradox) - Word processors (WordPerfect, Microsoft Word) - Games (many titles from the late 1980s/1990s) - RAM disks and disk caches Consult each program's documentation for EMS configuration options. Technical Details (for programmers): EMS is accessed via INT 67h. Key functions: AH=40h Get EMS status AH=41h Get page frame segment AH=42h Get total/free page count AH=43h Allocate handle and pages AH=44h Map logical page to physical page AH=45h Deallocate handle AH=46h Get EMS version (returns 4.0) See Appendix B for batch file techniques. For EMS programming details, consult the EMS 4.0 specification. ANSI CONSOLE DRIVER (ANSI.SYS) DR DOS includes ANSI.SYS, a loadable device driver that adds support for ANSI/VT100 escape sequences in console output. Programs can use escape sequences to position the cursor, set text colors, clear the screen, and perform other display operations without using direct BIOS calls. Enabling ANSI.SYS: Load the driver via CONFIG.SYS: DEVICE=ANSI.SYS Create or edit C:\CONFIG.SYS to include this line, then reboot. Supported Escape Sequences: ANSI.SYS recognizes the following ESC[ sequences (ESC = character 27): Cursor Movement: ESC[nA Move cursor up n rows (default 1) ESC[nB Move cursor down n rows (default 1) ESC[nC Move cursor forward n columns (default 1) ESC[nD Move cursor backward n columns (default 1) ESC[r;cH Move cursor to row r, column c (1-based) Cursor Save/Restore: ESC[s Save current cursor position ESC[u Restore saved cursor position Screen Control: ESC[2J Clear entire screen and home cursor ESC[K Erase from cursor to end of line Text Attributes (SGR): ESC[0m Reset all attributes to default ESC[1m Bold (high intensity) ESC[5m Blinking text ESC[7m Reverse video ESC[30-37m Set foreground color ESC[40-47m Set background color Color Values: 30/40 = Black 34/44 = Blue 31/41 = Red 35/45 = Magenta 32/42 = Green 36/46 = Cyan 33/43 = Yellow 37/47 = White Multiple attributes can be combined: ESC[1;31;40m (bold red on black) Without ANSI.SYS loaded, escape sequences are not interpreted and appear as literal characters on screen. EXTENDED MEMORY (XMS) DR DOS includes a built-in XMS 2.0 compatible extended memory driver, providing access to memory above the 1MB boundary on 386 and higher processors. What is XMS? Extended Memory Specification (XMS) is a standard for accessing memory above 1MB in real mode. Unlike EMS which uses page mapping, XMS provides direct access to extended memory through block move operations. DR DOS XMS Features: - XMS 2.0 compatible - Automatic detection of available extended memory - Up to 32 simultaneous memory handles - High Memory Area (HMA) support for kernel - Used as backing store for EMS driver XMS is available automatically on systems with extended memory. No configuration or drivers are required. Checking XMS Availability: Use MEM to see extended memory status: C:\>MEM The memory summary will show XMS memory if available. High Memory Area (HMA): The HMA is the first 64KB of extended memory (minus 16 bytes). DR DOS loads part of its kernel into the HMA, freeing conventional memory for applications. The HMA is managed automatically by the system. Programs that Use XMS: Many DOS applications and extenders use XMS: - DOS extenders (DOS4GW, PMODE, etc.) - Disk caches (SMARTDRV) - RAM disks - Large applications (compilers, CAD programs) Technical Details (for programmers): XMS is detected via INT 2Fh AX=4300h and accessed through an entry point obtained via INT 2Fh AX=4310h. Key functions: AH=00h Get XMS version (AX=0200h, XMS 2.0 spec; BX=0260h driver revision, reported for Windows 3.0 HIMEM compatibility) AH=08h Query free extended memory AH=09h Allocate extended memory block AH=0Ah Free extended memory block AH=0Bh Move extended memory block For XMS programming details, consult the XMS 2.0 specification. CTRL-C AND BREAK Pressing Ctrl-C during keyboard input aborts the current program and returns to the command prompt. DR DOS displays "^C" on the screen when Ctrl-C is detected. Ctrl-C is checked during the following operations: - Character input with echo (INT 21h AH=01h) - Character input without echo (INT 21h AH=08h) - Buffered keyboard input (INT 21h AH=0Ah) - Keyboard status check (INT 21h AH=0Bh) Direct console I/O (INT 21h AH=06h, 07h) does not check for Ctrl-C, allowing programs to read raw keystrokes when needed. By default, Ctrl-C is only checked during character I/O operations. Programs can enable extended break checking via INT 21h AH=33h (BREAK=ON), which causes Ctrl-C to be checked before every DOS call. This makes long-running operations (file copies, disk scans) more responsive to Ctrl-C. Applications may install their own INT 23h handler to customize Ctrl-C behavior. The default handler installed by COMMAND.COM echoes "^C" and aborts the current program. DISK ERROR HANDLING When a disk read or write fails, DR DOS retries the operation up to three times. If all retries are exhausted, the system invokes the critical error handler (INT 24h). The default behavior is to fail the operation and return an error code to the calling program. COMMAND.COM installs its own critical error handler at startup. The interactive "Abort, Retry, Fail?" prompt is not yet available; disk errors currently result in an error code returned to the calling program. Applications may install their own critical error handler to provide custom error recovery. The handler receives the drive number, error type, and BIOS error code, and returns an action code: 0 = Ignore (pretend the operation succeeded) 1 = Retry (attempt the operation again) 2 = Abort (terminate the program) 3 = Fail (fail the DOS call with an error code) CHANGING DRIVES You can change the current drive by typing the drive letter followed by a colon: Syntax: drive: Examples: A: Switch to floppy drive A: B: Switch to floppy drive B: (same physical drive as A: on single-floppy systems) C: Switch to drive C: D: Switch to drive D: The command prompt will update to show the new current drive. Each drive maintains its own current directory, so switching back to a drive returns you to the directory you were in on that drive. CLEARING THE SCREEN Use the CLS command to clear the screen and position the cursor at the top-left corner. Syntax: CLS NOTE: CLS is an external command. The file CLS.COM must be in the current directory or in the C:\DOS\ directory. =============================================================================== CHAPTER 7: COMMAND REFERENCE =============================================================================== This chapter describes all available DR DOS commands in alphabetical order. ------------------------------------------------------------------------------- BATCH - Batch File Interpreter ------------------------------------------------------------------------------- Executes batch file (.BAT) scripts. This command is invoked automatically by COMMAND.COM when you run a .BAT file; you do not normally run it directly. Syntax: BATCH filename [parameters] Parameters: filename The batch file to execute parameters Optional parameters passed to the batch file as %1-%9 Supported Batch Commands: Flow Control: REM Comment (ignored) ECHO Display text or control echoing PAUSE Wait for keypress GOTO Jump to label (including GOTO :EOF to exit) :label Label definition CALL Execute another batch file and return @ Suppress echo for current line Conditionals: IF EXIST Test if file exists IF ERRORLEVEL Test program exit code IF "str"=="str" Compare strings IF NOT Negate any condition File Operations: COPY Copy files DEL/ERASE Delete files REN/RENAME Rename files and directories MD/MKDIR Create directories RD/RMDIR Remove directories CD/CHDIR Change directory Variables: SET Display or modify environment variables %0-%9 Parameter substitution %VARNAME% Environment variable expansion SHIFT Shift parameters left Redirection: cmd > file Redirect output to file Examples: BATCH CLEANUP.BAT BATCH INSTALL.BAT C:\GAMES Notes: - BATCH is an external command; BATCH.COM must be available in C:\DOS\. - You typically run batch files by typing their name directly (e.g., CLEANUP or CLEANUP.BAT). COMMAND.COM automatically invokes BATCH.COM. - See Appendix B for complete batch programming documentation. Related commands: None ------------------------------------------------------------------------------- CD - Change Directory ------------------------------------------------------------------------------- Changes the current directory or displays the current directory path. Syntax: CD [drive:][path] Parameters: drive: The drive containing the directory (optional) path The directory to change to Examples: CD Display current directory CD \ Change to root directory CD .. Change to parent directory CD \DOS Change to \DOS directory CD SUBDIR Change to SUBDIR within current directory CD.. Change to parent (space optional) CD\ Change to root (space optional) CD/ Change to root (space optional) Notes: - CD and CHDIR are identical commands. - Spaces are optional when using .., \, or / as the path. - To change drives, type the drive letter followed by a colon (for example, D:) rather than using CD. Related commands: DIR ------------------------------------------------------------------------------- CHDIR - Change Directory ------------------------------------------------------------------------------- Identical to CD. See CD for details. ------------------------------------------------------------------------------- CLS - Clear Screen ------------------------------------------------------------------------------- Clears the screen and positions the cursor at the top-left corner. Syntax: CLS Parameters: None Examples: CLS Notes: - CLS is an external command; CLS.COM must be available in the current directory or in C:\DOS\. Related commands: None ------------------------------------------------------------------------------- COPY - Copy Files ------------------------------------------------------------------------------- Copies a file from one location to another. Syntax: COPY source destination Parameters: source The file to copy destination The target filename or directory Examples: COPY README.TXT README.BAK COPY D:DATA.TXT C:\BACKUP\ COPY LETTER.DOC D: Notes: - If the destination is a drive letter only (e.g., D:), the file is copied with the same name. - If the destination file already exists, it is overwritten without warning. - If the source and destination resolve to the same file, COPY refuses with "Source and Destination cannot be the same file" and reports "0 file(s) copied". The file is not modified. - This version of COPY does not support wildcard characters. Related commands: MOVE ------------------------------------------------------------------------------- DATE - Display or Set Date ------------------------------------------------------------------------------- Displays the current system date or sets a new date. Syntax: DATE [mm-dd-yyyy] Parameters: mm-dd-yyyy Optional new date (month-day-year) Examples: DATE Display current date and prompt for new date DATE 12-25-2025 Set date to December 25, 2025 DATE 01/15/2026 Set date to January 15, 2026 Notes: - DATE is an external command; DATE.COM must be available. - When called without parameters, DATE displays the current date with day-of-week and prompts for a new date. - Date format is flexible: use -, /, or other delimiters. - Two-digit years are interpreted as: 80-99 = 19xx, 00-79 = 20xx - Valid year range: 1980-2099 - Press ENTER at the date prompt to keep the current date. Related commands: None ------------------------------------------------------------------------------- DEL - Delete File ------------------------------------------------------------------------------- Deletes one or more files from the disk. Syntax: DEL filename ERASE filename Parameters: filename The file to delete (may include wildcards) Examples: DEL LETTER.TXT ERASE REPORT.DOC DEL *.BAK Notes: - DEL and ERASE are identical commands. - Wildcard characters are supported. - The file cannot be read-only; it must have its read-only attribute cleared first. Related commands: COPY ------------------------------------------------------------------------------- DIR - Directory Listing ------------------------------------------------------------------------------- Displays a list of files and subdirectories in a directory. Syntax: DIR [drive:][path][filespec] [/W] Parameters: drive: The drive to list (optional) path The directory to list (optional) filespec File specification, may include wildcards (optional) Switches: /W Wide format (5 columns, filenames only) Examples: DIR List current directory DIR *.TXT List all .TXT files DIR /W List files in wide format DIR D: List files on drive D: DIR \DOS List files in \DOS directory DIR C:\*.COM List all .COM files in root of C: Output: The listing shows: - Volume label (if any) - Volume serial number (if the disk has one, shown as XXXX-XXXX) - Directory path - File names, sizes, dates (MM-DD-YY), and times (H:MMa/p) - Subdirectories (marked with ) - Total number of files and bytes With /W switch, only file names are shown in a compact 5-column format without size, date, or time information. Related commands: CD ------------------------------------------------------------------------------- EDIT - Full-Screen Text Editor ------------------------------------------------------------------------------- Opens a full-screen text editor for creating and editing text files. Syntax: EDIT [filename] Parameters: filename Optional file to open for editing Screen Layout: The editor uses a colored display: - Top row: Menu bar (File, Edit, Search) and current filename - Middle rows: Text editing area (white text on blue background) - Bottom row: Status bar showing line number, column, and modified indicator Menu Access: Alt+F Open File menu (New, Open, Save, Save As, Exit) Alt+E Open Edit menu (Cut, Copy, Paste) Alt+S Open Search menu (Find, Find Next) Navigate menus with arrow keys. Press Enter to select an item or Escape to close the menu. Keyboard Shortcuts: Ctrl+N New file Ctrl+O Open file Ctrl+S Save file Ctrl+F Find F3 Find Next (repeat last search) Ctrl+X Cut line Ctrl+C Copy line Ctrl+V Paste Alt+X Exit editor Navigation: Arrow keys Move cursor Home Move to beginning of line End Move to end of line Page Up Scroll up one page Page Down Scroll down one page Ctrl+Home Move to beginning of file Ctrl+End Move to end of file Editing: Backspace Delete character before cursor Delete Delete character at cursor Enter Insert new line Tab Insert spaces to next tab stop Clipboard Operations (Edit menu): Cut Copy current line to clipboard and delete it Copy Copy current line to clipboard Paste Insert clipboard contents at cursor Examples: EDIT Open editor with empty file EDIT README.TXT Open README.TXT for editing EDIT NEWFILE.TXT Create and edit a new file Notes: - EDIT is an external command; EDIT.COM must be available in the current directory or in C:\DOS\. - Maximum file size is limited by available conventional memory. - Files are saved with CR+LF line endings. - Lines longer than 80 characters are truncated on display. Related commands: TYPE, MORE ------------------------------------------------------------------------------- ECHO - Display Message ------------------------------------------------------------------------------- Displays a message, prints a blank line, or controls command echoing. Syntax: ECHO message ECHO. ECHO ECHO ON ECHO OFF Parameters: message Text to display on screen ON Enable command echoing (commands are displayed before execution) OFF Disable command echoing (commands execute silently) Examples: ECHO Hello, World! Display "Hello, World!" ECHO. Display a blank line ECHO Display current echo state (ECHO is on/off) ECHO OFF Suppress command display Notes: - ECHO is a built-in command, always available. - ECHO. (period immediately after ECHO, no space) prints a blank line. - ECHO ON/OFF controls whether commands are displayed before execution. This is primarily useful in batch files; at the interactive prompt, commands are not echoed regardless of the setting. - ECHO with no arguments displays the current echo state. Related commands: None ------------------------------------------------------------------------------- ERASE - Delete File ------------------------------------------------------------------------------- Identical to DEL. See DEL for details. ------------------------------------------------------------------------------- EXIT - Exit Command Interpreter ------------------------------------------------------------------------------- Terminates the command interpreter (COMMAND.COM). Syntax: EXIT Parameters: None Notes: - If COMMAND.COM was started by another program, EXIT returns to that program. - If EXIT is typed at the initial DOS prompt, results may vary depending on system configuration. WARNING: Do not type EXIT at the main system prompt unless you understand the consequences. ------------------------------------------------------------------------------- FDISK - Fixed Disk Setup Program ------------------------------------------------------------------------------- Partitions hard disks with MBR partition tables. Creates, deletes, and manages primary DOS partitions. Syntax: FDISK FDISK /STATUS FDISK /AUTO n FDISK /MBR Switches: /STATUS Display partition table without modification /AUTO n Non-interactive: create a partition on drive n (1 = first hard disk, 2 = second, etc.) /MBR Rewrite MBR bootstrap code, preserving the existing partition table Interactive Mode: When run without switches, FDISK presents a menu: 1. Create DOS partition 2. Set active partition 3. Delete DOS partition 4. Display partition information 5. Change current fixed disk drive Use option 1 to create a new partition, option 2 to mark a partition as bootable, and option 4 to review the current layout. On systems with multiple hard disks, use option 5 to switch between drives. Partition Types: FDISK automatically selects the correct partition type based on partition size and disk geometry: FAT12 (type 01h) Partitions up to 16 MB FAT16 (type 04h) Partitions up to 32 MB FAT16B (type 06h) Partitions up to 2 GB (CHS-addressable) FAT16 (type 0Eh) Partitions requiring LBA addressing Partitions are track-aligned (start at LBA 63) and cylinder-aligned at the end, following standard DOS-era conventions. Examples: FDISK Start interactive partitioning FDISK /STATUS Display current partition table FDISK /AUTO 1 Create partition on first hard disk FDISK /MBR Rewrite MBR bootstrap code Notes: - FDISK is an external command; FDISK.COM must be available in the current directory or in C:\DOS\. - After creating or deleting partitions, reboot before using the modified disk. - Use FORMAT to create a filesystem on a newly partitioned drive. - FDISK only manages primary partitions. Extended partitions are not supported. WARNING: Deleting a partition destroys all data on that partition. Related commands: FORMAT ------------------------------------------------------------------------------- FORMAT - Format Disk ------------------------------------------------------------------------------- Creates FAT12 or FAT16 filesystems on partitioned hard disk drives. Writes the volume boot record, FAT tables, and root directory. Syntax: FORMAT drive: [/Q] [/V] [/S] Parameters: drive: The drive letter to format (e.g., C: or D:) Switches: /Q Quick format. Clears the FAT and root directory without performing a surface verification of the disk. /V Prompt for a volume label after formatting. /S System. Transfer system files after formatting, making the disk bootable. Copies DRBIOS.SYS, DRDOS.SYS, and COMMAND.COM to the formatted drive. Examples: FORMAT D: Format drive D: FORMAT D: /Q Quick format drive D: FORMAT D: /V Format and prompt for volume label FORMAT D: /S Format and make bootable FORMAT D: /Q /S /V Quick format, make bootable, set label Output: FORMAT displays a confirmation prompt before proceeding, then shows progress during formatting. On completion, it reports: - Total disk space - Bytes available on disk - Bytes per allocation unit - Number of allocation units - Volume serial number Notes: - FORMAT is an external command; FORMAT.COM must be available in the current directory or in C:\DOS\. - The target drive must already have a partition (see FDISK). - FORMAT automatically detects whether to use FAT12 or FAT16 based on partition size. - The /S switch requires DRBIOS.SYS, DRDOS.SYS, and COMMAND.COM to be available on the current drive. - FORMAT refuses to format the boot drive or the current drive and reports an error. - FORMAT returns an exit code (ERRORLEVEL): 0 on success, 3 if you decline the confirmation prompt, 4 on a formatting error, and 5 when the target is the boot drive or the current drive. WARNING: Formatting a drive destroys all data on that drive. FORMAT will prompt for confirmation before proceeding. Related commands: FDISK ------------------------------------------------------------------------------- HEXDUMP - Display Hex Dump ------------------------------------------------------------------------------- Displays a hexadecimal dump of a binary file. Syntax: HEXDUMP filename Parameters: filename The file to display Examples: HEXDUMP COMMAND.COM HEXDUMP PROGRAM.EXE Output: Each line shows: - Hexadecimal offset from start of file - 16 bytes in hexadecimal format - ASCII representation (non-printable characters shown as ".") Notes: - HEXDUMP is an external command; HEXDUMP.COM must be available. - Handles files larger than 64KB. - Useful for examining binary files, debugging, and data recovery. Related commands: TYPE ------------------------------------------------------------------------------- JMP - Execute Code at Memory Address ------------------------------------------------------------------------------- Performs a far call to a flat 20-bit real-mode memory address, transferring CPU execution to whatever code lives there. Completes the PEEK/POKE/JMP trio for direct memory manipulation. The target address is called (not jumped to), meaning code at that address can return to DOS cleanly by executing a far return (RETF instruction). If the target code never returns — because it jumps elsewhere, resets the machine, or calls INT 20h — JMP.COM simply never returns either. Syntax: JMP address Parameters: address Flat memory address in hex with h suffix, up to 5 digits. Range: 0h to FFFFFh. Examples: JMP FFFF0h Call BIOS cold-reset vector — resets the machine JMP 100h Execute code at 0010:0000 Entry state seen by called code: CS:IP = target address SS:SP = JMP.COM stack; return address on top (use RETF to return) DS,ES = JMP.COM data segment Registers AX-DI: undefined — target should not rely on any value Notes: - JMP is an external command; JMP.COM must be available in the current directory or in C:\DOS\. - The primary workflow is: use POKE to write machine code into a scratch area of RAM, then use JMP to execute it. This gives you an inline code execution capability from the command line. - JMP FFFF0h is a reliable way to cold-reset the machine — it calls the BIOS reset entry point directly, the same vector the CPU jumps to on power-on. - If called code returns via RETF, JMP.COM exits to DOS normally. If called code calls INT 20h or INT 21h AH=4Ch, the process terminates and DOS gets control back either way. WARNING: Jumping to an address that contains garbage or random data will crash the system immediately. Always know what is at an address before jumping to it. Use PEEK and HEXDUMP to inspect memory first. Related commands: PEEK, POKE ------------------------------------------------------------------------------- MD - Make Directory ------------------------------------------------------------------------------- Creates a new directory. Syntax: MD dirname MKDIR dirname Parameters: dirname The name of the new directory Examples: MD DOCS MKDIR BACKUPS Notes: - MD and MKDIR are identical commands. - The parent directory must already exist. - If a directory with the same name already exists, MD will return an error instead of creating a duplicate entry. - Wildcard characters are not supported. Related commands: CD, RD ------------------------------------------------------------------------------- MEM - Display Memory Information ------------------------------------------------------------------------------- Displays comprehensive system memory information. Syntax: MEM [switches] Switches: /H /? Display help text /B Show conventional memory blocks (MCB chain) /U Show upper memory blocks (UMB chain) /F Show HMA (High Memory Area) blocks /D Show device drivers /S Show system structures /M Show system memory map with ASCII visualization /A Show all information (combines all modes) /P Pause listing at each page (23 lines) Examples: MEM Display memory summary MEM /B Show conventional memory blocks MEM /M Show memory map with visualization MEM /A Show all available information MEM /A /P Show all information with paging Output: The default output shows a summary table with: - Conventional memory (0-640KB) - High memory area (HMA) - Extended memory (XMS) - Total memory available Additional switches provide detailed block-by-block information including owner, size, and memory visualization. Notes: - MEM is an external command; MEM.COM must be available. - Switches can be combined (e.g., MEM /B /U /P) - The /M switch provides an ASCII art visualization of the entire memory map. - Very useful for diagnosing memory issues and understanding system configuration. Related commands: None ------------------------------------------------------------------------------- MORE - Display Output One Page at a Time ------------------------------------------------------------------------------- Displays a text file one page at a time, pausing after each screenful. Syntax: MORE filename command | MORE Parameters: filename The file to display Controls: Space Display next page (23 lines) Enter Display next line Q or Esc Quit Examples: MORE README.TXT TYPE BIGFILE.TXT | MORE DIR | MORE MEM /A | MORE Notes: - MORE is an external command; MORE.COM must be available in the current directory or in C:\DOS\. - When used with piping (|), the output of the preceding command is displayed one page at a time. - The "-- More --" prompt appears at the bottom of each page. - Use TYPE for quick viewing of short files; use MORE for long files. Related commands: TYPE ------------------------------------------------------------------------------- MOUSE - PS/2 Mouse Driver ------------------------------------------------------------------------------- Loads a resident PS/2 mouse driver that provides the standard INT 33h mouse API used by DOS applications and games. Syntax: MOUSE Parameters: None Examples: MOUSE Load the mouse driver before running applications that require mouse support (e.g., games, editors, menu-driven programs). Output: If a PS/2 mouse is detected, the driver installs itself as a Terminate-and-Stay-Resident (TSR) program and displays: DR DOS 9.0 PS/2 Mouse Driver v1.0 Mouse detected - driver installed. If no PS/2 mouse is detected, the driver displays an error and exits without going resident. Mouse Cursor: Applications control the mouse cursor through INT 33h calls. In text mode, the cursor appears as an inverse-video block character. Notes: - MOUSE is an external command; MOUSE.COM must be available in the current directory or in C:\DOS\. - The driver uses BIOS INT 15h PS/2 pointing device services for hardware access. A PS/2-compatible mouse (or emulation) is required. - Once loaded, the driver remains in memory. Reboot to unload. - Load MOUSE before starting any application that needs mouse input. Related commands: None ------------------------------------------------------------------------------- MKDIR - Make Directory ------------------------------------------------------------------------------- Identical to MD. See MD for details. ------------------------------------------------------------------------------- MOVE - Move Files ------------------------------------------------------------------------------- Moves a file from one location to another, removing the original. Syntax: MOVE source destination Parameters: source The file to move destination The target filename or directory Examples: MOVE OLD.TXT NEW.TXT MOVE C:\DOCS\FILE.TXT D:\BACKUP\ MOVE *.BAK D:\ARCHIVE\ Notes: - MOVE is an external command; MOVE.COM must be available. - If the destination file exists, MOVE will prompt before overwriting. - Enter Y for yes, N for no, or A for all to overwrite all remaining files without prompting. - MOVE supports wildcard characters in the source filespec. Related commands: COPY ------------------------------------------------------------------------------- PEEK - Read Byte from Memory Address ------------------------------------------------------------------------------- Reads a single byte from any flat real-mode memory address and displays it as two uppercase hex digits. Addresses span the full 20-bit real-mode address space (0h through FFFFFh), giving direct access to conventional memory, video RAM, the BIOS data area, and the interrupt vector table. Syntax: PEEK address Parameters: address Flat memory address in hex with h suffix (e.g. B8000h). Up to 5 hex digits. Range: 0h to FFFFFh. Examples: PEEK 0h Read first byte of interrupt vector table PEEK 46Ch Read low byte of BIOS timer tick counter PEEK B8000h Read first character byte of text video RAM PEEK A0000h Read first byte of VGA graphics framebuffer Output: A two-digit uppercase hex value followed by a newline: FF Notes: - PEEK is an external command; PEEK.COM must be available in the current directory or in C:\DOS\. - Addresses are entered in hexadecimal with an h suffix. No 0x prefix is used. Both uppercase and lowercase hex digits are accepted. - The full 1 MB real-mode address space is accessible. There is no memory protection; any address may be read. - See the PC memory map below for notable addresses. PC Memory Map (selected addresses): 0h - 3FFh Interrupt vector table (256 vectors x 4 bytes) 400h - 4FFh BIOS data area (equipment flags, cursor, etc.) 46Ch BIOS timer tick counter low word 472h Warm boot flag (1234h = warm boot) B8000h - BFFFFh CGA/VGA text mode video RAM A0000h - AFFFFh VGA graphics framebuffer (mode 13h, etc.) B0000h - B7FFFh Monochrome display adapter RAM C0000h - EFFFFh ROM space (video BIOS, adapter ROMs) F0000h - FFFFFh System BIOS ROM Related commands: POKE, JMP, HEXDUMP ------------------------------------------------------------------------------- POKE - Write Byte to Memory Address ------------------------------------------------------------------------------- Writes a single byte to any flat real-mode memory address. Like PEEK, addresses span the full 20-bit real-mode address space (0h through FFFFFh). On success, prints "OK" unless suppressed with /S. Syntax: POKE address value [/S] Parameters: address Flat memory address in hex with h suffix (e.g. B8000h). Up to 5 hex digits. Range: 0h to FFFFFh. value Byte value to write, in hex with h suffix (e.g. FFh). Range: 0h to FFh. Switches: /S Silent. Suppresses the "OK" confirmation message. Examples: POKE B8000h 41h Write 'A' to first character of text video RAM POKE B8001h 1Fh Write bright-white-on-blue attribute byte POKE B8001h 80h Set blink attribute on first character POKE 46Ch 0h Reset BIOS timer low byte (sets clock toward midnight) POKE 100h FFh /S Write silently, no output Notes: - POKE is an external command; POKE.COM must be available in the current directory or in C:\DOS\. - Addresses and values are entered in hexadecimal with an h suffix. Both uppercase and lowercase hex digits are accepted. - The /S switch may appear anywhere after the two required arguments. WARNING: POKE has direct, unprotected access to all of physical memory. Writing to the wrong address can crash the system immediately and without any error message. There is no undo. In particular: - Addresses 0h-3FFh are the interrupt vector table. Corrupting a vector will cause a crash the next time that interrupt fires. The hardware timer (INT 8h, vector at 20h-23h) fires approximately 18 times per second; corrupting it will crash the system within milliseconds whether or not you are doing anything. - Addresses 84h-87h hold the INT 21h (DOS API) vector. Corrupting this causes a crash on the very next DOS call, which COMMAND.COM makes constantly. - ROM addresses (C0000h and above) cannot be written. The write will silently have no effect. Related commands: PEEK, JMP, HEXDUMP ------------------------------------------------------------------------------- REBOOT - Restart System ------------------------------------------------------------------------------- Restarts the computer. Syntax: REBOOT Parameters: None Notes: - REBOOT is an external command; REBOOT.COM must be available. - All unsaved work will be lost. - This performs a warm boot (restart) of the system. WARNING: Save all work before using REBOOT. ------------------------------------------------------------------------------- REN - Rename File or Directory ------------------------------------------------------------------------------- Renames an existing file or directory. Can also move a file or directory to a different location on the same drive. Syntax: REN oldname newname RENAME oldname newname Parameters: oldname The current name (or path) of the file or directory newname The new name (or path) for the file or directory Examples: REN OLD.TXT NEW.TXT RENAME LETTER.DOC LETTER.BAK REN DOCS ARCHIVE REN \WORK\REPORT.TXT \DONE\REPORT.TXT Notes: - REN and RENAME are identical commands. - Wildcard characters are not supported. - The new name cannot already exist in the destination directory. - REN can move files and directories across directories on the same drive. Cross-drive moves are not supported; use COPY and DEL instead. - When renaming a directory, all files and subdirectories within it are preserved. Related commands: COPY, MOVE ------------------------------------------------------------------------------- RENAME - Rename File or Directory ------------------------------------------------------------------------------- Identical to REN. See REN for details. ------------------------------------------------------------------------------- SET - Display or Modify Environment Variables ------------------------------------------------------------------------------- Displays, searches, creates, modifies, or removes environment variables. Syntax: SET SET prefix SET name=value SET name= Parameters: (none) Display all environment variables prefix Display variables whose names start with prefix name=value Set variable name to value name= Remove variable name from the environment Examples: SET Display all variables SET C Display variables starting with C SET MYDIR=C:\WORK Create or update MYDIR SET MYDIR= Remove MYDIR Notes: - SET is a built-in command, always available at the interactive prompt and in batch files. - Variable names are case-insensitive. - Variables can be referenced in commands and batch files using %VARNAME% syntax. - The COMSPEC variable is set automatically by the system and should not be modified. Related commands: ECHO ------------------------------------------------------------------------------- RD - Remove Directory ------------------------------------------------------------------------------- Removes an empty directory. Syntax: RD dirname RMDIR dirname Parameters: dirname The directory to remove Examples: RD TEMP RD C:\OLD\BACKUP RMDIR EMPTY Notes: - RD and RMDIR are identical commands. - The directory must be empty before it can be removed. - You cannot remove the current directory. - You cannot remove the root directory. Related commands: MD, CD ------------------------------------------------------------------------------- RMDIR - Remove Directory ------------------------------------------------------------------------------- Identical to RD. See RD for details. ------------------------------------------------------------------------------- TYPE - Display File Contents ------------------------------------------------------------------------------- Displays the contents of a text file on screen. Syntax: TYPE filename Parameters: filename The file to display Examples: TYPE README.TXT TYPE C:\DOCS\LETTER.DOC Notes: - TYPE is an external command; TYPE.COM must be available. - Use TYPE only on text files. Binary files will display meaningless characters. - For long files, use TYPE filename | MORE to page through the output one screen at a time. Related commands: COPY, HEXDUMP, MORE ------------------------------------------------------------------------------- VER - Display Version ------------------------------------------------------------------------------- Displays the DR DOS version number. Syntax: VER Parameters: None Output: DR DOS (R) 9.0 rev 80 Copyright 2022-2026 Whitehorn Ltd. Co., All Rights Reserved The revision number shown (e.g., "rev 80") indicates the build version. Notes: - VER is a built-in command, always available. Related commands: None =============================================================================== APPENDIX A: ERROR MESSAGES =============================================================================== This appendix lists error messages you may encounter and their meanings. Bad command or file name The command you typed is not a built-in command, and no program with that name was found in the current directory or in C:\DOS\. Solution: Check the spelling of the command. Verify that the program file exists in the expected location. File not found - The file you specified does not exist. Solution: Check the spelling of the filename. Use DIR to verify the file exists in the expected location. Invalid directory The directory path you specified does not exist. Solution: Check the spelling of the directory name. Use DIR to see available directories. Required parameter missing A command requires a parameter that you did not provide. Solution: Check the command syntax and provide all required parameters. Unable to create destination file The system could not create the destination file. Solution: Verify that the destination directory exists and that the disk is not write-protected or full. Read error An error occurred while reading from the disk. The kernel retries the operation up to three times before reporting the failure. Solution: The disk may be damaged. Try the operation again. If the problem persists, the disk may need to be replaced. Write error An error occurred while writing to the disk. The kernel retries the operation up to three times before reporting the failure. Solution: The disk may be full, write-protected, or damaged. Check disk space and write-protect status. Access denied - You attempted to access a file that is protected. Solution: The file may be read-only or in use by another program. Clear the read-only attribute before attempting to modify the file. Unable to create directory The system could not create the directory. Solution: Verify that the parent directory exists. The directory you're trying to create must be inside an existing directory. Duplicate file name or file not found An error occurred while renaming a file. Solution: The new name may already exist, or the old name does not exist. Use DIR to verify the file names. Overwrite (Yes/No/All)? The destination file already exists during a MOVE operation. Solution: Enter Y to overwrite this file, N to skip it, or A to overwrite all remaining files without prompting. Error moving file An error occurred while moving a file. Solution: Check the file names and ensure you have permission to access both the source and destination files. File not found No files were found matching the specified pattern. Solution: Check the filename or pattern. Use DIR to see available files. Invalid parameter An invalid parameter was provided. Solution: Check the command syntax and ensure all parameters are valid. Syntax: MOVE source destination The MOVE command was called with incorrect syntax. Solution: Check the MOVE command syntax and ensure you provide both a source and destination. =============================================================================== APPENDIX B: BATCH PROGRAMMING GUIDE =============================================================================== This appendix is a comprehensive programmer's reference for writing batch scripts in DR DOS. It covers all supported commands, flow control, variable handling, file operations, and practical patterns. WHAT IS A BATCH FILE? A batch file is a plain text file with a .BAT extension containing a sequence of commands executed line by line. Batch files automate repetitive tasks, create simple installers, and build menus. Create batch files with EDIT or any text editor. Each line contains one command. Blank lines are ignored. ------------------------------------------------------------------------------- COMMENTS: REM ------------------------------------------------------------------------------- Use REM to add comments. Everything after REM on the line is ignored. REM This is a comment REM Author: John Smith REM Last modified: February 2026 Comments document your script's purpose, explain complex logic, and leave notes for future maintenance. ------------------------------------------------------------------------------- DISPLAYING TEXT: ECHO ------------------------------------------------------------------------------- ECHO displays messages to the screen. ECHO Hello, World! ECHO Installation complete. ECHO. ECHO. (with a period, no space) prints a blank line. Echo State: By default, each command is displayed before execution. Control this with ECHO OFF and ECHO ON: ECHO OFF REM Commands below this line are not displayed ECHO This message still appears ECHO ON REM Commands are displayed again ECHO OFF suppresses command display but ECHO messages still appear. Use ECHO alone (no argument) to display the current echo state. ------------------------------------------------------------------------------- SUPPRESSING ECHO: @ ------------------------------------------------------------------------------- Prefix any command with @ to suppress its display for that line only. @ECHO OFF This is the standard first line of most batch files. The @ prevents "ECHO OFF" from being displayed, and ECHO OFF prevents subsequent commands from being displayed. @REM This comment won't be displayed @PAUSE ------------------------------------------------------------------------------- WAITING FOR INPUT: PAUSE ------------------------------------------------------------------------------- PAUSE halts execution and displays "Press any key to continue . . ." until the user presses a key. ECHO About to delete temporary files... PAUSE DEL *.TMP Use PAUSE to give users time to read messages or confirm before potentially destructive operations. ------------------------------------------------------------------------------- LABELS AND GOTO ------------------------------------------------------------------------------- Labels mark locations in your script. A label is a line beginning with a colon followed by a name: :START :MENU :END Label names are case-insensitive. :START, :Start, and :start are identical. GOTO transfers execution to a label: GOTO END ECHO This line is never executed :END ECHO Script finished Exiting Early with GOTO :EOF: Use GOTO :EOF to exit the batch file immediately without needing to define an :END label: @ECHO OFF IF "%1"=="" ( ECHO Missing parameter! GOTO :EOF ) ECHO Processing %1... This is cleaner than jumping to a label at the end of the file. Creating Loops: Combine GOTO with labels to create loops: :LOOP ECHO Press any key to continue, or Ctrl+C to exit PAUSE GOTO LOOP Organizing Code Sections: @ECHO OFF GOTO MAIN :USAGE ECHO Usage: INSTALL source GOTO :EOF :MAIN IF "%1"=="" GOTO USAGE ECHO Installing from %1... COPY %1 C:\PROGRAM\ ------------------------------------------------------------------------------- CONDITIONAL EXECUTION: IF ------------------------------------------------------------------------------- IF executes a command only when a condition is true. Testing File Existence: IF EXIST CONFIG.SYS ECHO Config file found IF EXIST C:\DOS\MOUSE.COM MOUSE IF EXIST checks whether a file exists. The command after the filename executes only if the file is found. Testing Device Names: IF EXIST also works with device names like NUL and CON: IF EXIST NUL ECHO Device support available Since NUL is a built-in device, this always succeeds. This can be used to verify batch file compatibility. String Comparison: IF "%1"=="HELP" GOTO SHOWHELP IF "%1"=="" ECHO No parameter provided Strings must be enclosed in double quotes. The comparison is case-sensitive: "YES" does not equal "yes". Tip: Always quote both sides when comparing parameters. If %1 is empty, IF %1=="" becomes IF =="" which is a syntax error. Using IF "%1"=="" becomes IF ""=="" which works correctly. Testing Exit Codes with ERRORLEVEL: Programs return exit codes (0-255) when they finish. Use IF ERRORLEVEL to test these codes and handle success or failure: PROGRAM.EXE IF ERRORLEVEL 1 ECHO Program failed! IF ERRORLEVEL 0 ECHO Program succeeded! IF ERRORLEVEL n is true if the exit code is GREATER THAN OR EQUAL TO n. This means you must test higher values first: MYAPP.EXE IF ERRORLEVEL 3 GOTO FATAL_ERROR IF ERRORLEVEL 2 GOTO SERIOUS_ERROR IF ERRORLEVEL 1 GOTO MINOR_ERROR ECHO Success! GOTO :EOF :MINOR_ERROR ECHO Warning: minor issue detected GOTO :EOF :SERIOUS_ERROR ECHO Error: something went wrong GOTO :EOF :FATAL_ERROR ECHO FATAL: critical failure! GOTO :EOF Standard DOS Error Codes: Programs return exit codes (also called error codes or return codes) that indicate success or failure. These codes are accessible via ERRORLEVEL. Code Meaning ---- --------------------------------------------------------- 0 Success - operation completed without error 1 General error - operation failed 2 File not found - specified file does not exist 3 Path not found - specified directory does not exist 4 Too many open files - system file handle limit reached 5 Access denied - file is read-only or in use 8 Insufficient memory - not enough RAM for operation 15 Invalid drive - drive letter does not exist 18 No more files - used internally by FindFirst/FindNext DR DOS Command Exit Codes: Built-in and external commands return these codes: Command Success Failure Notes -------- ------- ------- ------------------------------------ COPY 0 1 1 if source not found or write fails DEL 0 1 1 if file not found or access denied REN 0 1 1 if file not found or name exists MD 0 1 1 if directory exists or path invalid RD 0 1 1 if directory not empty or not found CD 0 1 1 if directory not found TYPE 0 1 1 if file not found DIR 0 1 1 if path not found (not if no files) MOVE 0 1 1 if source not found or move fails EDIT 0 - Always returns 0 MEM 0 - Always returns 0 Testing Multiple Error Levels: Remember that IF ERRORLEVEL n is true when the code is >= n. Always test higher values first to distinguish between different error conditions: MYAPP.EXE IF ERRORLEVEL 5 GOTO ACCESS_DENIED IF ERRORLEVEL 3 GOTO PATH_ERROR IF ERRORLEVEL 2 GOTO FILE_ERROR IF ERRORLEVEL 1 GOTO GENERAL_ERROR ECHO Operation successful. GOTO :EOF :FILE_ERROR ECHO Error: File not found. GOTO :EOF :PATH_ERROR ECHO Error: Directory not found. GOTO :EOF :ACCESS_DENIED ECHO Error: Access denied - check file permissions. GOTO :EOF :GENERAL_ERROR ECHO Error: Operation failed. Negating Conditions: IF NOT reverses the condition: IF NOT EXIST TEMP MD TEMP IF NOT "%1"=="" GOTO PROCESS IF NOT ERRORLEVEL 1 ECHO Success! This creates the TEMP directory only if it doesn't exist, processes only if a parameter was provided, or reports success if exit code is 0. ------------------------------------------------------------------------------- PARAMETERS: %0 THROUGH %9 ------------------------------------------------------------------------------- Batch files accept up to 9 parameters from the command line, accessed as %1 through %9. %0 contains the batch file's own name. Example batch file GREET.BAT: @ECHO OFF ECHO Hello, %1! ECHO This script is: %0 Running: GREET John Output: Hello, John! This script is: GREET.BAT Using Multiple Parameters: BACKUP.BAT: @ECHO OFF IF "%1"=="" GOTO USAGE IF "%2"=="" GOTO USAGE ECHO Copying %1 to %2... COPY %1 %2 ECHO Done. GOTO :EOF :USAGE ECHO Usage: BACKUP source destination Running: BACKUP README.TXT D:\BACKUP\README.TXT Literal Percent Sign: Use %% to include a literal percent sign: ECHO Disk is 50%% full Displays: Disk is 50% full ------------------------------------------------------------------------------- SHIFT: ACCESSING MORE THAN 9 PARAMETERS ------------------------------------------------------------------------------- SHIFT moves all parameters down by one position: Before SHIFT: %0=SCRIPT %1=A %2=B %3=C %4=D After SHIFT: %0=A %1=B %2=C %3=D %4=(empty) This allows processing an unlimited number of parameters in a loop: LISTALL.BAT - Display all parameters: @ECHO OFF :LOOP IF "%1"=="" GOTO :EOF ECHO Parameter: %1 SHIFT GOTO LOOP Running: LISTALL one two three four five six Output: Parameter: one Parameter: two Parameter: three Parameter: four Parameter: five Parameter: six Processing Multiple Files: DELALL.BAT - Delete all specified files: @ECHO OFF IF "%1"=="" GOTO USAGE :LOOP IF "%1"=="" GOTO DONE IF EXIST %1 DEL %1 IF EXIST %1 ECHO Failed to delete: %1 IF NOT EXIST %1 ECHO Deleted: %1 SHIFT GOTO LOOP :DONE ECHO All files processed. GOTO :EOF :USAGE ECHO Usage: DELALL file1 file2 file3 ... Note: After SHIFT, the original %0 (script name) is lost. Save it to a variable first if needed. ------------------------------------------------------------------------------- ENVIRONMENT VARIABLES: %VARNAME% ------------------------------------------------------------------------------- Access environment variables by surrounding the name with percent signs: ECHO Command interpreter: %COMSPEC% ECHO My directory: %MYDIR% If the variable doesn't exist, the text is left unchanged: ECHO Value is: %UNDEFINED% Output: Value is: %UNDEFINED% Using Variables in Conditions: IF "%COMSPEC%"=="" ECHO COMSPEC not defined! IF NOT "%MYDIR%"=="" ECHO MYDIR is set Working with Environment Variables using SET: Use SET with no arguments to display all environment variables: SET Use SET with a prefix to show only matching variables: SET P Show variables starting with P SET COM Show variables starting with COM Use SET VAR=value to create or modify a variable: SET MYDIR=C:\WORK SET GREETING=Hello Use SET VAR= (with nothing after the equals sign) to remove a variable: SET MYDIR= ------------------------------------------------------------------------------- CALLING OTHER BATCH FILES: CALL ------------------------------------------------------------------------------- Use CALL to execute another batch file and return to continue: @ECHO OFF ECHO Starting installation... CALL SETUP.BAT ECHO Setup complete, running configuration... CALL CONFIG.BAT %1 ECHO All done! Without CALL, executing a batch file transfers control permanently and does not return to the calling script. Passing Parameters: Parameters passed to CALL are available in the called script: MAIN.BAT: @ECHO OFF CALL HELPER.BAT first second HELPER.BAT: @ECHO OFF ECHO Received: %1 and %2 Running MAIN.BAT outputs: Received: first and second Nested Calls: Batch files can call other batch files that call others: MAIN.BAT -> CALL INIT.BAT -> CALL CHECK.BAT -> returns -> returns Each CALL remembers where to return. Deep nesting may exhaust memory. ------------------------------------------------------------------------------- FILE OPERATIONS ------------------------------------------------------------------------------- Batch files include built-in commands for common file operations. COPY - Copy Files: COPY README.TXT BACKUP.TXT COPY %1 %2 COPY README.TXT BACKUP.TXT DEL / ERASE - Delete Files: DEL TEMP.TXT DEL *.BAK ERASE OLD.DAT Wildcards (* and ?) are supported. REN / RENAME - Rename Files and Directories: REN OLDNAME.TXT NEWNAME.TXT REN DOCS ARCHIVE REN \WORK\FILE.TXT \DONE\FILE.TXT RENAME %1 %2 MD / MKDIR - Create Directories: MD NEWDIR MKDIR C:\PROGRAMS\MYAPP IF NOT EXIST TEMP MD TEMP RD / RMDIR - Remove Directories: RD EMPTYDIR RMDIR C:\OLD\TEMP The directory must be empty. CD / CHDIR - Change Directory: CD \ CHDIR C:\DOS CD .. CD.. (space optional) Changes the current directory for subsequent commands. ------------------------------------------------------------------------------- OUTPUT REDIRECTION ------------------------------------------------------------------------------- Redirect command output to a file using >: DIR > FILELIST.TXT ECHO Installation log > INSTALL.LOG MEM > MEMINFO.TXT The file is created or overwritten. Discarding Output with NUL: Redirect to NUL to discard unwanted output: DEL *.TMP > NUL COPY FILE.DAT BACKUP.DAT > NUL This suppresses success messages while still showing errors. Note: Input redirection (<) and append redirection (>>) are not supported. ------------------------------------------------------------------------------- PRACTICAL PATTERNS ------------------------------------------------------------------------------- Standard Script Header: @ECHO OFF REM ============================================= REM SCRIPTNAME.BAT - Brief description REM Author: Your Name REM Date: February 2026 REM ============================================= Parameter Validation: @ECHO OFF IF "%1"=="" GOTO USAGE IF "%2"=="" GOTO USAGE REM ... main script logic ... GOTO :EOF :USAGE ECHO Usage: %0 source destination ECHO. ECHO Copies source file to destination. Error Handling with ERRORLEVEL: @ECHO OFF ECHO Compiling program... COMPILER.EXE %1 IF ERRORLEVEL 1 GOTO FAILED ECHO Compilation successful! GOTO :EOF :FAILED ECHO Compilation failed with errors. Cleanup on Exit: @ECHO OFF ECHO Creating temporary files... COPY %1 TEMP.DAT REM ... do work ... ECHO Cleaning up... DEL TEMP.DAT ECHO Done. Installer Pattern: @ECHO OFF ECHO ================================ ECHO MyProgram Installation ECHO ================================ ECHO. REM Check for required parameter IF "%1"=="" GOTO USAGE REM Create installation directory IF NOT EXIST C:\MYAPP MD C:\MYAPP REM Copy files ECHO Copying files... COPY %1\MYAPP.EXE C:\MYAPP\ > NUL IF ERRORLEVEL 1 GOTO FAILED ECHO. ECHO Installation complete! ECHO Run C:\MYAPP\MYAPP.EXE to start. GOTO :EOF :FAILED ECHO Installation failed! GOTO :EOF :USAGE ECHO Usage: INSTALL sourcedir Conditional Setup: @ECHO OFF IF NOT EXIST C:\GAMES MD C:\GAMES IF EXIST C:\GAMES\GAME.EXE GOTO RUN ECHO Game not installed. GOTO :EOF :RUN C:\GAMES\GAME.EXE Processing Multiple Files with Wildcards: Use wildcards to operate on groups of files: @ECHO OFF ECHO Deleting all backup files... DEL *.BAK DEL *.TMP DEL *.OLD ECHO Done. Using CALL for Modular Scripts: MAIN.BAT: @ECHO OFF CALL INIT.BAT IF ERRORLEVEL 1 GOTO FAILED CALL PROCESS.BAT %1 IF ERRORLEVEL 1 GOTO FAILED CALL CLEANUP.BAT ECHO Success! GOTO :EOF :FAILED ECHO An error occurred. ------------------------------------------------------------------------------- DEBUGGING TIPS ------------------------------------------------------------------------------- Remove @ECHO OFF Temporarily: Comment out or remove @ECHO OFF to see each command as it executes: REM @ECHO OFF IF "%1"=="" GOTO USAGE ... This shows exactly what the batch file is doing. Add Progress Messages: ECHO DEBUG: About to copy files... COPY %1 %2 IF ERRORLEVEL 1 ECHO DEBUG: Copy FAILED IF NOT ERRORLEVEL 1 ECHO DEBUG: Copy successful Use PAUSE for Breakpoints: ECHO About to delete files - press Ctrl+C to abort PAUSE DEL *.TMP Check Variable Values: ECHO Parameter 1 is: [%1] ECHO Parameter 2 is: [%2] Brackets make it easy to spot empty or whitespace values. ------------------------------------------------------------------------------- QUICK REFERENCE ------------------------------------------------------------------------------- Flow Control: ------------------ -------------------------------------------------- REM text Comment (ignored) ECHO message Display message ECHO. Display blank line ECHO OFF Stop displaying commands ECHO ON Resume displaying commands @command Execute without displaying this line PAUSE Wait for keypress :label Define a label (target for GOTO) GOTO label Jump to label GOTO :EOF Exit batch file immediately CALL file [args] Execute batch file and return Conditionals: ------------------ -------------------------------------------------- IF EXIST file cmd Execute cmd if file exists IF NOT EXIST file cmd Execute cmd if file doesn't exist IF ERRORLEVEL n cmd Execute cmd if exit code >= n IF NOT ERRORLEVEL n Execute cmd if exit code < n IF "a"=="b" cmd Execute cmd if strings match IF NOT "a"=="b" cmd Execute cmd if strings differ Variables: ------------------ -------------------------------------------------- %0 Batch file name %1 - %9 Command line parameters %% Literal percent sign %VARNAME% Environment variable value SHIFT Shift parameters left SET Display all environment variables SET prefix Display variables starting with prefix SET VAR=value Set environment variable SET VAR= Remove environment variable File Operations: ------------------ -------------------------------------------------- COPY src dest Copy a file DEL file Delete a file (also: ERASE) MOVE src dest Move a file REN old new Rename a file or directory (also: RENAME) MD dir Create directory (also: MKDIR) RD dir Remove directory (also: RMDIR) CD path Change directory (also: CHDIR) Redirection: ------------------ -------------------------------------------------- cmd > file Redirect output to file cmd > NUL Discard output ------------------------------------------------------------------------------- EXAMPLE PROGRAMS ------------------------------------------------------------------------------- This section provides complete, ready-to-use batch file examples that demonstrate common tasks and techniques. All examples use only features available in DR DOS. Example 1: CLEANUP.BAT - Delete Temporary Files ------------------------------------------------ Removes common temporary files from the current directory. @ECHO OFF REM ============================================= REM CLEANUP.BAT - Remove temporary files REM ============================================= ECHO Cleaning up temporary files... ECHO. IF EXIST *.TMP DEL *.TMP IF EXIST *.BAK DEL *.BAK IF EXIST *.OLD DEL *.OLD ECHO Cleanup complete. Example 2: BACKUP.BAT - Backup Files to Another Directory ---------------------------------------------------------- Copies important files to a backup directory, creating it if needed. @ECHO OFF REM ============================================= REM BACKUP.BAT - Backup files to D:\BACKUP REM Usage: BACKUP filename REM ============================================= IF "%1"=="" GOTO USAGE REM Create backup directory if it doesn't exist IF NOT EXIST D:\BACKUP MD D:\BACKUP REM Check if source file exists IF NOT EXIST %1 GOTO NOTFOUND ECHO Backing up %1 to D:\BACKUP... COPY %1 D:\BACKUP IF ERRORLEVEL 1 GOTO FAILED ECHO Backup successful. GOTO :EOF :NOTFOUND ECHO ERROR: File %1 not found. GOTO :EOF :FAILED ECHO ERROR: Backup failed. GOTO :EOF :USAGE ECHO Usage: BACKUP filename ECHO. ECHO Copies the specified file to D:\BACKUP directory. Example 3: INSTALL.BAT - Simple Installer ------------------------------------------ Installs a program to a target directory with error checking. @ECHO OFF REM ============================================= REM INSTALL.BAT - Install MyProgram REM Usage: INSTALL [source_dir] REM ============================================= ECHO ================================ ECHO MyProgram Installation ECHO ================================ ECHO. REM Default source is current directory IF "%1"=="" GOTO USE_CURRENT IF NOT EXIST %1\MYAPP.EXE GOTO NOTFOUND GOTO INSTALL :USE_CURRENT IF NOT EXIST MYAPP.EXE GOTO NOTFOUND :INSTALL ECHO Creating program directory... IF NOT EXIST C:\MYAPP MD C:\MYAPP ECHO Copying program files... IF "%1"=="" GOTO COPY_CURRENT COPY %1\MYAPP.EXE C:\MYAPP > NUL GOTO CHECK_COPY :COPY_CURRENT COPY MYAPP.EXE C:\MYAPP > NUL :CHECK_COPY IF ERRORLEVEL 1 GOTO FAILED ECHO. ECHO Installation complete! ECHO. ECHO Run C:\MYAPP\MYAPP.EXE to start the program. GOTO :EOF :NOTFOUND ECHO ERROR: MYAPP.EXE not found. ECHO Please specify the source directory. GOTO :EOF :FAILED ECHO ERROR: Installation failed. Example 4: MENU.BAT - Simple Menu System ----------------------------------------- Displays a menu and runs programs based on batch file parameter. @ECHO OFF REM ============================================= REM MENU.BAT - Main Menu REM Usage: MENU [choice] REM ============================================= :SHOW_MENU CLS ECHO. ECHO ======================================== ECHO MAIN MENU ECHO ======================================== ECHO. ECHO 1. Run Directory Listing ECHO 2. Display Memory Status ECHO 3. Run Cleanup ECHO 4. Exit to DOS ECHO. ECHO To select, type: MENU 1, MENU 2, MENU 3, or MENU 4 ECHO. IF "%1"=="" GOTO :EOF IF "%1"=="1" GOTO OPTION1 IF "%1"=="2" GOTO OPTION2 IF "%1"=="3" GOTO OPTION3 IF "%1"=="4" GOTO :EOF ECHO Invalid choice: %1 GOTO :EOF :OPTION1 DIR PAUSE GOTO :EOF :OPTION2 MEM PAUSE GOTO :EOF :OPTION3 CALL CLEANUP.BAT PAUSE GOTO :EOF Example 5: DEPLOY.BAT - Multi-Step Deployment ---------------------------------------------- Demonstrates CALL, ERRORLEVEL checking, and multi-step operations. @ECHO OFF REM ============================================= REM DEPLOY.BAT - Deploy application files REM Usage: DEPLOY source_dir target_dir REM ============================================= IF "%1"=="" GOTO USAGE IF "%2"=="" GOTO USAGE ECHO Starting deployment... ECHO Source: %1 ECHO Target: %2 ECHO. REM Step 1: Validate source ECHO Step 1: Validating source directory... IF NOT EXIST %1 GOTO NO_SOURCE REM Step 2: Create target ECHO Step 2: Creating target directory... IF NOT EXIST %2 MD %2 IF ERRORLEVEL 1 GOTO MKDIR_FAILED REM Step 3: Copy new files ECHO Step 3: Copying new files... COPY %1\APP.EXE %2 > NUL IF ERRORLEVEL 1 GOTO COPY_FAILED ECHO. ECHO Deployment successful! GOTO :EOF :NO_SOURCE ECHO ERROR: Source directory %1 not found. GOTO :EOF :MKDIR_FAILED ECHO ERROR: Could not create directory %2. GOTO :EOF :COPY_FAILED ECHO ERROR: File copy failed. GOTO :EOF :USAGE ECHO Usage: DEPLOY source_dir target_dir ECHO. ECHO Copies all files from source to target directory. Example 6: ALLPARAM.BAT - Process All Parameters with SHIFT ------------------------------------------------------------ Demonstrates using SHIFT to handle unlimited parameters. @ECHO OFF REM ============================================= REM ALLPARAM.BAT - Process all command-line parameters REM Usage: ALLPARAM file1 file2 file3 ... REM ============================================= IF "%1"=="" GOTO USAGE ECHO Processing files... ECHO. :LOOP IF "%1"=="" GOTO DONE ECHO Checking: %1 IF EXIST %1 ECHO - File exists IF NOT EXIST %1 ECHO - File NOT found SHIFT GOTO LOOP :DONE ECHO. ECHO All parameters processed. GOTO :EOF :USAGE ECHO Usage: ALLPARAM file1 file2 file3 ... ECHO. ECHO Checks each specified file and reports if it exists. Example 7: SAFEDEL.BAT - Safe Delete with Confirmation ------------------------------------------------------- Deletes files only after confirming they exist. @ECHO OFF REM ============================================= REM SAFEDEL.BAT - Delete file with safety checks REM Usage: SAFEDEL filename REM ============================================= IF "%1"=="" GOTO USAGE IF NOT EXIST %1 GOTO NOTFOUND ECHO File to delete: %1 ECHO. ECHO Press any key to delete, or Ctrl+C to cancel... PAUSE > NUL DEL %1 IF ERRORLEVEL 1 GOTO FAILED IF EXIST %1 GOTO FAILED ECHO File deleted successfully. GOTO :EOF :NOTFOUND ECHO File %1 does not exist. GOTO :EOF :FAILED ECHO ERROR: Could not delete %1. GOTO :EOF :USAGE ECHO Usage: SAFEDEL filename ECHO. ECHO Deletes the specified file after confirmation. Example 8: DIRLOG.BAT - Save Directory Listing ----------------------------------------------- Saves a directory listing to a text file for later reference. @ECHO OFF REM ============================================= REM DIRLOG.BAT - Save directory listing to file REM Usage: DIRLOG [directory] REM ============================================= IF "%1"=="" GOTO CURRENT IF NOT EXIST %1 GOTO NOTFOUND CD %1 :CURRENT ECHO Saving directory listing... DIR > DIRLIST.TXT ECHO Directory saved to DIRLIST.TXT ECHO. ECHO Contents: TYPE DIRLIST.TXT GOTO :EOF :NOTFOUND ECHO Directory %1 not found. Example 9: RUNAPP.BAT - Run Application with Setup --------------------------------------------------- Sets up the environment before running a program. @ECHO OFF REM ============================================= REM RUNAPP.BAT - Run application with setup REM ============================================= ECHO Setting up environment... REM Ensure required directories exist IF NOT EXIST C:\TEMP MD C:\TEMP IF NOT EXIST C:\APP\DATA MD C:\APP\DATA REM Change to application directory CD C:\APP REM Run the application ECHO Starting application... MYAPP.EXE REM Check exit status IF ERRORLEVEL 1 GOTO ERROR ECHO Application completed normally. GOTO :EOF :ERROR ECHO Application exited with an error. Example 10: DAILY.BAT - Daily Maintenance Tasks ------------------------------------------------ Combines multiple maintenance operations into one script. @ECHO OFF REM ============================================= REM DAILY.BAT - Daily system maintenance REM Run this batch file once per day REM ============================================= ECHO ======================================== ECHO Daily Maintenance Starting ECHO ======================================== ECHO. REM Step 1: Clean temporary files ECHO Step 1: Cleaning temporary files... CD C:\TEMP IF EXIST *.TMP DEL *.TMP IF EXIST *.BAK DEL *.BAK CD \ REM Step 2: Create backup directory with today's files ECHO Step 2: Backing up important files... IF NOT EXIST D:\DAILY MD D:\DAILY IF EXIST C:\DOCS\README.TXT COPY C:\DOCS\README.TXT D:\DAILY > NUL REM Step 3: Report completion ECHO. ECHO ======================================== ECHO Maintenance Complete ECHO ======================================== ECHO. ECHO Temporary files cleaned. ECHO Documents backed up to D:\DAILY. ------------------------------------------------------------------------------- LIMITATIONS ------------------------------------------------------------------------------- The following features are NOT supported in DR DOS batch files: - FOR loops (FOR %%v IN (set) DO command) - Input redirection (<) - Append redirection (>>) - Pipes within batch files - Delayed variable expansion - CHOICE command for menus =============================================================================== APPENDIX C: REPORTING BUGS AND ISSUES =============================================================================== DR DOS 9.0 is currently in beta testing. We appreciate your help in making DR DOS better by reporting any issues you encounter. During beta testing, you may experience bugs, crashes, system freezes, filesystem corruption, or hardware and software compatibility issues. These are expected during this phase of development, and your reports help us identify and fix problems. WHAT TO REPORT Please report any of the following: - System crashes or freezes - Filesystem corruption or data loss - Programs that don't run correctly - Unexpected error messages - Hardware or software incompatibilities - Any behavior that seems incorrect or unusual HOW TO REPORT A BUG You can report bugs in two ways: - Fill out the support form at: https://www.dr-dos.com/support.html - Send an email to: bugs@dr-dos.com Please include the following information in your report: 1. Version and Revision Run the VER command at the DOS prompt to see your version. It will display something like "DR DOS 9.0 rev 80". Include the complete version string in your report. 2. Hardware or Virtualization Environment Examples: - QEMU 10.2 on Windows 11 - VirtualBox 7.0 on Linux - Intel Pentium II PC with 440LX chipset, 128MB RAM - 86Box emulator 3. What You Were Doing Describe the task you were performing when the issue occurred. Examples: - "I was installing Lotus 1-2-3" - "I was playing Commander Keen Episode 1" - "I was copying files from C: to D:" 4. What Happened Describe what you saw on screen. Screenshots or photos are very helpful if possible. Include any error messages exactly as shown. GETTING HELP Website: https://www.dr-dos.com Support: https://www.dr-dos.com/support.html Bug Reports: bugs@dr-dos.com Check the website for documentation, updates, and known issues. Thank you for helping us improve DR DOS! =============================================================================== GLOSSARY =============================================================================== AUTOEXEC.BAT A batch file in the root directory of the boot drive that DR DOS executes automatically at startup. Used to set environment variables, load programs, and configure the system. Batch file A text file with a .BAT extension containing commands to be executed in sequence. Used for automation and scripting. Boot The process of starting up a computer and loading the operating system. CHS Cylinder-Head-Sector. A method of addressing disk sectors using the physical geometry of the drive. Common on systems before 1994. DR DOS fully supports CHS disk addressing. Command interpreter The program (COMMAND.COM) that displays the DOS prompt and executes your commands. Command prompt The text displayed by DOS (e.g., C:\>) indicating it is ready to accept a command. CONFIG.SYS A configuration file in the root directory that DR DOS processes at boot time. Used to load device drivers (DEVICE), set file handles (FILES), configure the command interpreter (SHELL), and control other system settings. Conventional memory The first 640KB of memory, directly accessible by DOS programs. This is the primary memory space for running programs. Current directory The directory where DOS looks for files by default. Displayed in the command prompt. Device A hardware component or pseudo-device accessible through a reserved name. DOS devices include CON (console), NUL (null device), AUX (auxiliary), and PRN (printer). Directory A container for files and other directories, used to organize the contents of a disk. Drive A device that reads and writes data to storage media. Identified by a letter (A:, C:, D:, etc.). EMS Expanded Memory Specification. A standard for accessing memory beyond 640KB through a page-mapped window. DR DOS provides EMS 4.0 support via the EMM386.SYS driver loaded in CONFIG.SYS. Environment variable A named value stored in the system environment, accessible to programs and batch files. Example: COMSPEC. ERRORLEVEL The exit code returned by a program when it finishes. Used in batch files with IF ERRORLEVEL to test for success or failure. Extension The part of a filename after the period, typically indicating the file type. Limited to 3 characters. External command A command that exists as a separate program file (.COM or .EXE) rather than being built into COMMAND.COM. FAT12 File Allocation Table (12-bit). A filesystem format used on floppy disks and small hard disk partitions. DR DOS supports FAT12 on all drives and detects it automatically. FAT16 File Allocation Table (16-bit). A filesystem format used on hard disk partitions. DR DOS supports FAT16 on all drives and detects it automatically. File A named collection of data stored on disk. HMA High Memory Area. The first 64KB of extended memory (minus 16 bytes), accessible in real mode. Used by DR DOS to load part of the kernel, freeing conventional memory. Internal command A command built into COMMAND.COM, always available without needing a separate program file. LBA Logical Block Addressing. A method of addressing disk sectors using a linear block number. Common on systems from 1994 onward. DR DOS fully supports LBA disk addressing. NUL A special device that discards all output written to it and returns empty input when read. Useful for suppressing output: command > NUL Page frame A 64KB window in upper memory (typically at segment D000h) through which EMS expanded memory pages are accessed. Parameter Information provided to a command that modifies its behavior. Path The complete specification of a file's location, including drive, directories, and filename. Redirection Sending a command's output to a file instead of the screen, using the > operator. Root directory The top-level directory on a disk, from which all other directories branch. VCPI Virtual Control Program Interface. A standard allowing DOS extenders and protected-mode programs to coexist with EMS memory managers. EMM386.SYS provides VCPI support. Wildcard A special character (* or ?) that matches multiple characters in a filename, used to specify groups of files. XMS Extended Memory Specification. A standard for accessing extended memory (above 1MB) on 286 and higher processors. DR DOS includes a built-in XMS driver and uses XMS as backing store for EMS. =============================================================================== END OF USER GUIDE =============================================================================== WHITEHORN LTD. CO. 3963 S Highway 97 #214 Sand Springs, OK 74063 DR DOS is a registered trademark of Whitehorn Ltd. Co. Copyright (c) 2022-2026 Whitehorn Ltd. Co. All rights reserved.