)
Values for VNETBIOS action code:
 00h	"VN_Unknown" unknown command
 04h	"VN_No_Map"  no memory mapping necessary
 08h	"VN_Map_In"  input buffer is quickly used, so no global mapping needed
 0Ch	"VN_Map_In"  output buffer is quickly used, so no global mapping needed
 10h	"VN_Map_In_Out"	 buffer is quickly used, so no global mapping needed
 14h	"VN_Chain_Send"	 the chain-send command
 18h	"VN_Cancel"	special case for cancel command
 1Ch	"VN_Buffer_In"	buffer is incoming
 20h	"VN_Buffer_Out" buffer is outgoing
 24h	"VN_Buffer_In_Out" buffer used for both incoming and outgoing data