VDDs / VCOMPAT

vCOMPAT is a special VDD, that will fix some issues in VDMs to further enhance compatibility.
It contains plenty of fixes and some of them are user-controlable via Properties.

• COMPATIBILITY_2GBSIZELIMIT
  will limit the size virtually to 2GB on any drive reported to DOS applications
• COMPATIBILITY_CDROM
  will make fix some CD-ROM APIs to act like in real DOS
• COMPATIBILITY_DPMI
  will include some DPMI work-arounds and activate the magical VM patcher for DPMI patching
• COMPATIBILITY_DPMI_ANTICLI
  will activate the AntiCLI code in the magical VM patcher (more information in vCOMPAT.txt)
• COMPATIBILITY_JOYSTICKBIOS
  will emulate BIOS joystick functions (if implemented incorrectly by BIOS manufacturer)
• COMPATIBILITY_MOUSESENSE
  will make the mouse more sensitive (only meant for some games)
• Magical VM Patcher, will fix the following problems on-the-fly on any application:
  - Turbo Pascal CRT Unit run-time error 200 bug (Realmode and DPMI)
  - M$ C Library "Division by Zero" bug
  - Non-compliant DPMI code (aka infamous CLI bug)
• Some other issues that are not documented here

Download vCOMPAT v0.32b - by Martin Kiewitz (D/Ls )

History

• Another CD-ROM specific inaccuracy in VDM. Thanx to Max Alekseyev for pointing this out
• Support for vCDROM replacement (disabling of CD-ROM related patches, which will safe realmode-memory)
• Reworked the realmode injector, uses VDD-space now and much less V86 memory now

• Magical VM Patcher hooks moved from VDM to VDD-space
• DPMI Anti-CLI code included
• DPMI Workarounds for application "bugs" (e.g. Sam'n Max and Alien Legacy)
• Magical VM Patcher also removes DPMI Turbo Pascal CRT Unit bug

• COMPATIBILITY_CDAUDIO got renamed into COMPATIBILITY_CDROM. It includes all CD-ROM specific fixes and a new one, that caused some installation software to believe that A: would be a CD-ROM.

• Find1st-Patch is now only applied on CD-ROM access (bug is in original MSCDEX actually)
• INT25h-Patch is now able to live with the "patched" INT25h done by IBM in their latest kernels (INT25h is supposed to be buggy, this bug was fixed by IBM, we are emulating it again)

• First public beta release