PMVDMCC.SYS

PMVDMCC.SYS was developed by Veit Kannegieser to address certain issues found on various systems, including but not limited to some ThinkPad models.

PMVDMCC.SYS alters the _VDMINT10CreateMiniVDMSub, _VDMInt13CreateMiniVDMSub and VDMInt13DestroyMiniVDM procedures in OS2KRNL to map more memory areas than the original procedures. This is useful to prevent hang or trap when booting using MemDisk on machines that are already memory constrained.

The problem was that filter code that is installed just below 640 KiB is not mapped, when it is located below 640-8 KiB.

Example machines where problems have been observed include IBM/Lenovo Thinkpads, where the boot process would stop when IBM1S506.ADD is used, or DANIS506.ADD with empty hard disk or without the /!BIOS option. Similar problems may occur when the machine is not docked on other machines where the desktop would appear (switch to high resolution graphics mode).

A by-product of this driver is the possibility to free the '2K STACK' and move the extended BIOS data area, so that when setting the DOS video mode restriction to CGA, it is possible to again achieve 730 KiB DOS session memory.

BASEDEV=PMVDMCC.SYS

Parameters

 * /Q :Suppress error messages
 * /V :Verbose diagnostic messages
 * /W :Verbose + pause for keypress before continuing
 * /F :Attempt to free "2K STACK"