INT 2A - DOS Network Critical Section and NETBIOS

	For more information see the following topics:

	 INT 2A,0  Network installation query
	 INT 2A,1  Execute NETBIOS request with no error retry
	 INT 2A,2  Set network printer mode (not listed)
	 INT 2A,3  Check if direct I/O allowed
	 INT 2A,4  Execute NETBIOS request
	 INT 2A,5  Get network resource information
	 INT 2A,6  Network print stream control
	INT 2A,80  Begin DOS critical section
	INT 2A,81  End DOS critical section
	INT 2A,82  End DOS critical sections 0 through 7
	INT 2A,84  Keyboard busy loop
	INT 2A,87  Critical section

	- functions requests are supplied in AH