Function 44h I/O Control for Devices (IOCTL) Get or Set Device Informationentry AH 44h
AL 00h Get Device Information (from DX)
BX file or device handle
return DX device info
If bit 7 set: (character device)
bit 0: console input device
1: console output device
2: NUL device
3: CLOCK$ device
4: device is special
5: binary (raw) mode
6: not EOF
12: network device (DOS 3.x)
14: can process IOCTL control
strings (func 2-5)
If bit 7 clear: (file)
bits 0-5: block device number
6: file has not been written
12: Network device (DOS 3.x)
15: file is remote (DOS 3.x)
Function 44h I/O Control for Devices (IOCTL) Get or Set Device Information
entry AH 44h
00h Get Device Information (from DX)
note This function can be used to detect input and output redirection. Since
the handle for STDOUT is always 1, if after calling Int 21 with AX=4400h
and BX=0001h, the character device bit (bit 7) and the console output
device bit (bit 1) are set in DX, anything sent to STDOUT will appear on
the screen. If bit 7 is clear, we know output is being redirected to a
file. If bit 1 is zero, the redirection is to another device.
file: /Techref/INT/21F/44SF/00.htm, 1KB, , updated: 1999/4/26 12:36, local time: 2024/8/14 18:02,
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