DOSBox-X Version 2025.12.01

DOSBox-X v2025.12.01 has been released, enhancing the DOSBox emulator for x86 PCs to run old MS-DOS games on modern systems. Key updates include a video debug overlay for Tandy and PCjr emulation, a startup string addition to support specific game requirements, and improvements to Tseng ET4000/ET3000 emulation addressing various graphic mode issues. The update also resolves a bug affecting drive change commands and modifies INT 21h to assist compatibility with specific games. Further fixes enhance Tandy machine type handling, ensuring better game performance and stability. Download DOSBox-X v2025.12.01 to experience these improvements.

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DOSBox-X v2025.12.01 has been released. DOSBox-X is an extension of DOSBox. DOSBox simulates an Intel x86 PC, including sound, graphics, mouse, joystick, modem, and more, making it possible to play many vintage MS-DOS games that cannot run on contemporary PCs and operating systems, such as Microsoft Windows XP, Windows Vista, Linux, and FreeBSD.

DOSBox-X Changelog:
Video debug overlay: For Tandy and PCjr emulation, includes information on
the screen detailing the line mask, display, and CPU memory banks, along with
the related segment values. This can help with debugging issues
in games and uncover potential remapping or page flipping (joncampbell123).
Tandy emulation: Inserts the string “Tandy” in the DOS kernel
during startup if machine=tandy. The game “The Train: Escape to Normandy”
searches from FFFF:0000 for the string “Tandy,” which wraps
to the first 64KB of memory where the DOS kernel is located. If the string is absent, it will not recognize the system as Tandy.
This change enables the game to run properly (joncampbell123).
Tseng ET4000 emulation: Mode 0x24 is notable for its 130×28
text mode with a 13-pixel tall character cell. The ET4000 VGA BIOS
features a designated font for that mode, so it has been included in DOSBox-X for mode 0x24 (joncampbell123).
Tseng ET4000 emulation: Corrects modes 0x22/0x23/0x24 to align with the
actual VGA BIOS programming. This resolves rendering issues where the 132×25
mode appeared only in the upper portion of the screen (joncampbell123).
Corrects a bug in Tseng ET3000/ET4000 emulation causing CGA graphics modes
to render incorrectly. The main VGA emulation no longer relies on M_CGA2/M_CGA4, and
the ET4000 emulation must function similarly to address graphics modes correctly. This fix also applies to ET3000 emulation (joncampbell123).
Some additional code in shell processing was hindering drive change commands
if the final character was a backslash, i.e., “a:” instead of “a:”.
This has been fixed (joncampbell123).
INT 21h AH=4Bh EXEC: Real MS-DOS returns a nonzero value like 0x3E01.
A faulty version of Magic Pockets fails to invoke INT 21 AH=4Dh to retrieve
the INTRO.EXE exit code and expects AL to simply be nonzero to proceed
with the game. Thus, to enable smoother functioning, a nonzero value is returned (joncampbell123).
Tandy machine type: Many registers are designated as WRITE ONLY in SX
documentation, yet “Troubadours” attempts to read/modify/write those
registers via custom manual modesetting code to configure the 320×200 16-color mode. Therefore, the code has been added to respond to reads
from those ports with zeros and log a debug message concerning how DOS games should not read those registers.
The custom modesetting should work by returning 0x00 instead of 0xFF.
Returning 0xFF will cause the mode setup to fail; returning 0x00 will allow it. Although the game may still crash frequently and in the same manner
on both DOSBox-X and DOSBox SVN, this fix addresses the issue of only being able to render 2 out of 4 scanlines on the screen (joncampbell123).