December 21, 2025 - written by richardg867

This is the December 2025 update to 86Box, bringing in performance improvements, bugfixes and some new hardware for the holidays.

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Main features

Several small and localized performance improvements have been made to emulation performance, including a new C runtime library for Windows host systems, optimizations to the “new” dynamic recompiler used on ARM and Apple Silicon host systems, as well as multithreading improvements to Voodoo and other video cards. We remain engaged in investigating more potential performance improvements for the next release.

The floppy drive sounds feature added last release got a big update, with improved accuracy especially in head seeks, and new recordings from two 3.5” and three 5.25” floppy drives. The recordings have been moved to a new package outside of the ROM set, so read below for more information before upgrading.

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Important changes

Asset pack and floppy sounds

Due to its large size, the floppy drive sound collection has been moved out of the ROM set and into a new asset pack, which is now included with release versions of 86Box downloaded from GitHub, as the assets folder inside the .zip on Windows, or embedded within the AppImage on Linux or the app bundle on macOS. Linux packages may or may not include the asset pack; we recommend maintainers to include it in /usr/share/86Box/assets as part of the standard 86Box package.

If you use our experimental builds or any other package without the asset pack, floppy sounds will not be available until you install the pack the same way you would install the ROM set. Download and decompress it into an assets folder next to (not inside!) the roms folder in any of the same places: next to the 86Box application (Windows executable, Linux AppImage or macOS app bundle) or in one of the system-wide locations for your host operating system.

On top of the asset pack change, the Mitsumi and Teac floppy drive recordings from v5.2 have been removed for technical reasons, so you may need to reconfigure floppy sounds after upgrading.

Windows 7 and 8 support

Windows 7 and 8 host systems are still supported for the time being, but on those Windows versions, the Visual C++ 2015 Redistributable must now be installed. You probably already have this installed by other applications or Windows updates, but in case you don’t and 86Box complains about a missing DLL, an installer can be downloaded from Microsoft’s website (get the x64 version).

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Changelog

Emulator

• Improved overall performance on Windows hosts by upgrading to the Universal C Runtime
• Added asset pack for floppy drive sounds and other future features
• Added customizable Ctrl+Alt+Page Down keyboard shortcut to show or hide the user interface in full screen mode
• Added toolbar button, Action menu option and customizable Ctrl+Alt+I keyboard shortcut to temporarily disable the dynamic recompiler for troublesome applications
• Added relative path conversion to disk images located next to the 86Box application or one level above the machine folder (for portable setups)
• Fixed OpenGL renderer crashing the emulator when taking screenshots
• Fixed emulated display resolution changes occasionally crashing the emulator

User interface

• Added a toolbar with quick commands to the manager
• Added icons to some menu entries
• Fixed refresh rate indicator displaying inaccurate numbers when a Voodoo add-in card is active
• Changed emulation speed indicator to be consistent across CPU frame size options
• Updated and cleaned up many translations

Machines

• 808x

• Added real time clock I/O port and IRQ configuration to the Multitech PC-500 and PC-500 plus

• Fixed Tandy 1000 family display shake effect used by some games

• 286

• Fixed extended memory support on C&T PC/AT machines

• Fixed Amstrad PC5286 keyboard issues when a PS/2 mouse is emulated

• 386

• Added Socket 1 486 CPU support to the IBM PS/55 model 5550-V

• Renamed IBM PS/55 model 5550-T to 5550-S/T Stage II

• Renamed IBM PS/55 model 5550-V to 5550-V0/V1 and changed category to 386DX/486

• 486

• Fixed incorrect on-board video BIOS on the IBM PS/ValuePoint 433DX/Si

• 586

• Added Socket 5 machine: HP Pavilion 50x0/70xx

• Added Socket 7 machines: ASUS TX97-XV, HP Pavilion 51xx/7070/7090/71xx, 52xx/53xx/71xx/72xx, 73xx/74xx

• Added on-board Crystal CS4232 sound to the Intel Advanced/AS, Advanced/ATX and Advanced/MA

• Added RM Accelerator 350P2XB/450P3XB BIOS variant option to the AOpen AX6BC

• Added Award BIOS option to the MSI MS-5124 and MS-5146

• Fixed BIOS settings for serial and parallel ports the Intel Advanced/ATX

• 686

• Added Slot 1 machine: MSI MS-6199VA (plus Compaq and Packard Bell BIOS variants)

• Added Socket 370 machines: MSI MS-6318 (plus Elonex, Fujitsu-Siemens, HP and Medion BIOS variants), Samsung CAIRO-5

• Added more BIOS version options to the ABIT AB-BX6

• Added Leadtek WinFast 8000BX BIOS variant option to the Supermicro P6SBA

• Changed maximum RAM on the AOpen AP61

Hardware

• Core

• Improved CPU performance on ARM hosts, especially on MMX applications

• Fixed specific FPU inaccuracy on ARM hosts leading to loss of sound on some Windows games

• Fixed INC/DEC instruction legality inaccuracy

• Display

• Improved emulation performance of Voodoo, ATI Mach64 and S3 video cards

• Fixed VideoMagic ETW32PVS (Tseng ET4000/W32p) VLB video card not being selectable on Linux and other case-sensitive systems

• Fixed IBM 8514/A ATI MCA variant crashing the emulator on startup on some hosts

• Fixed incorrect refresh rates on many cards (again)

• Fixed S3 ViRGE rendering glitches on full motion video applications (again)

• Fixed IBM XGA rendering glitches on specific color depths

• Fixed Matrox and Voodoo texture glitches on 3D applications

• Fixed Voodoo Banshee/3 text rendering glitches on Linux

• Fixed rendering issues with specific drivers on S3 9xx and Tseng ET4000/W32 cards

• Fixed transparency glitches with more games on Voodoo cards

• Fixed VGA scrolling behavior not matching real hardware on ATI Mach64 and Tseng ET4000/W32 cards

• Fixed incorrect dark gray color on the IBM 5153 CGA monitor

• Input

• Fixed XT keyboard key count option not taking effect

• Sound

• Added Crystal CS4232 ISA sound card

• Added OPTi 82C930 and 82C931 ISA sound cards

• Fixed Sound Blaster 16 and AWE sound issues on some DOS games

• Fixed incorrect default I/O port on the Covox Voice Master Key

• Removed Raise CODEC interrupt option from Aztech Sound Galaxy cards as it is no longer required

• Ports

• Fixed emulation hangs with serial passthrough to Windows named pipes in server mode (known issue: VMware serial ports fail to connect if 86Box is the pipe server; use VMware as the server and 86Box as the client instead)

• Storage

• Improved accuracy of floppy drive sounds

• Added a new set of floppy drive sounds

• Added IDE CD-ROM drive models: HITACHI CDR-8435 (for the RM Accelerator 350P2XB/450P3XB (AOpen AX6BC)), TOSHIBA CD-ROM XM-6102B

• Added SCSI CD-ROM drive models: NEC CD-ROM DRIVE:900, PLEXTOR CD-ROM PX-12CS, PX-12TS, PX-83CS, TOSHIBA CD-ROM XM-3701B

• Fixed missing DVD support on the HITACHI GD-7500 and HL-DT-ST DVDRAM GSA-4160 CD-ROM drive models

• Fixed Panasonic/MKE CD-ROM drives not being detected by OS/2

• Fixed floppy drive controller inaccuracy crashing 1B/V3

• Removed Mitsumi and Teac floppy drive sounds which could not be updated to the improved system

• Other

• Added base memory backfill support to the Everex EV-159 ISA memory expansion card