NV_PATCH by Jonathan Lawrence 16/3/94
Freeware - use at your own risk!

For users of NVDI:

NVDI's mouse handler routine (version 2.5 and maybe others) reduces 
the 680X0's IPL to 5.

On the Falcon this causes an almost immediate crash when the Tabby 
driver (operating off the serial port interrupt) tries to send 
mouse information.

Running NV_PATCH.PRG modifies NVDI.PRG to prevent this happening.
Reboot with the changed version and Tabby should work fine.
The patch may also fix problems with other mouse utilities that initiate 
mouse movement. (Mouse Tricks hyperspace)

Be sure to keep another copy of NVDI.PRG (renamed to NVDI_OLD.PRG?) 
just in case the patching goes wrong, or there are situations when 
the unmodified version is needed. (I can't think of any.)



For interested assembler programmers:

NV_PATCH.PRG changes the offending code to leave the IPL at 7.

The code in the mouse handler:
	ori.w	#$700,sr	IPL to 7
	andi.w	#$FDFF,sr	then down to 5

is changed to:
	ori.w	#$700,sr	IPL to 7
	andi.w	#$FFFF,sr	no change
	
NV_PATCH.PRG will have no effect on versions that don't include 
this code.
NVDI 2.5 has only one instance of this code - problems could arise
if any NVDI version used it more than once.