EBX: Is undefined but must be saved over this call.
ESI: Contains the VM handle for the MemC owner VM.
ECX: Contains the VM handle for the CRTC owner VM.
EBP: May or may not be pointing to the VM's client registers.
Save anything that you use.
The VDD has two special "pseudo-VM's" that are used by the VDD to set special states. The Blue Screen Message Mode pseudo-VM contains the states when Windows encounters a serious problem and displays a blue screen with an error message. This blue-screen message mode is displayed in VGA mode 3 in non-Far East versions of Windows 95 and in Mode 12h in Far East DBCS versions of Windows 95. The Forced Planar Mode pseudo-VM is a VM containing the 4 plane MemC state (such as that in Mode 12h). These "pseudo VM" handles are sometimes passed to the mini-VDD during calls to the RESTORE_REGISTERS. The mini-VDD should retrieve and save these special VM handles at MiniVDD_Dynamic_Init time, and then compare them against the handles passed to RESTORE_REGISTERS.
Use caution when restoring the two special VDD pseudo-VM. The VIDEO7.VXD sample mini-VDD contains an example of how these pseudo-VM's have their register states saved at Init_Complete time and how RESTORE_REGISTERS uses the pseudo VM handles to properly restore the state of the blue screen message mode.