DOS Fn 4400H and 4401H use this for values passed in DX. The bit flags
have different meanings, depending upon bit 7 (device or file).
IoctlDevInfoRec layout when describing a device
5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
1 0 0 0 0 1 e b f c n o i
0: 0001H Console Input device
1: 0002H Console Output device
4: 0010H special device; fast output
5: 0020H binary mode; 0=ASCII
6: 0040H not EOF; 0=EOF on input
13: 2000H spts output-till-busy DvRq 10H
15: 8000H 0=block device; 1=char device
IoctlFileInfoRec layout when describing a file
5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
0-5: 003fH drive ID (0=A, 1=B, etc.)
6: 0040H not EOF; 0=EOF on input
15: 8000H 0=block device; 1=char device
See Also: fn 4400H (IOCTL query device/file flags)
fn 4401H (IOCTL set device/file flags)