INT 2A - NETWORK (Microsoft,LANtastic) - CHECK DIRECT I/O
AX = 0300h
DS:SI -> ASCIZ device name (may be full path or only drive specifier--
must include the colon)
Return: CF clear if direct physical addressing (INT 13,INT 25) permissible
CF set if access via files only
Notes:  do not use direct disk accesses if this function returns CF set or the
device is redirected (INT 21/AX=5F02h)
may take some time to execute
called by DOS kernel on INT 25 and INT 26
SeeAlso: INT 25,INT 26,INT 21/AX=5F02h

See also: 13

2A0300 - NETWORK (Microsoft,LANtastic) - CHECK DIRECT I/O