The primary driver file associated with the Standard PS/2 Keyboard is often referred to as i8042prt.sys , though the device manager usually lists it under the "Standard PS/2 Keyboard" name using the kbdhid.sys (HID Keyboard Filter) and kbdclass.sys files.
Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\i8042prt . Locate the value in the right pane.