EBX: Contains a Windows VM Handle.
EBP: Points to the Windows VM's Client Registers.
Save anything that you use.
This function is called directly before the Main VDD virtualizes the VGA processor latches when doing 4 plane VGA virtualization in a window. The mini-VDD should save the current bank register state (for later restoration by RESET_LATCH_BANK) and set to the VGA virtualization bank which was determined at GET_VDD_BANK.