INT 21,44,0 / IOCTL,0 - Get Device Information

AH = 44h

AL = 00

BX = handle (must be an opened device)

on return

AX = error code if CF set (see ~DOS ERROR CODES~)

DX = device information (see tables below)

¦F¦E¦D¦C¦B¦A-8¦7¦6¦5-0¦ DX Block Device Information

¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +----- drive number (0=A:,1=B:)

¦ ¦ ¦ ¦ ¦ ¦ ¦ +------- 0 = file has been written

¦ ¦ ¦ ¦ ¦ ¦ +-------- 0 = disk file; 1 = character device

¦ ¦ ¦ ¦ ¦ +---------- reserved, must be zero

¦ ¦ ¦ ¦ +------------ 1 = media not removable

¦ ¦ ¦ +------------- 1 = network device (DOS 3.x+)

¦ ¦ +-------------- 1 = reserved

¦ +--------------- 1 = don't update file time or date (DOS 4.x+)

+---------------- 1 = file is remote (DOS 3.x+)

¦F¦E¦D¦C¦B¦A-8¦7¦6¦5¦4¦3¦2¦1¦0¦ DX Character Device Information

¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +---- 1 = standard input device

¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +---- 1 = standard output device

¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +---- 1 = NUL device

¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +---- 1 = clock device

¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +---- uses DOS ~INT 29~ for fast character output

¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +---- 1 = binary mode, 0 = translated

¦ ¦ ¦ ¦ ¦ ¦ ¦ +---- 0 = end of file on input

¦ ¦ ¦ ¦ ¦ ¦ +---- 1 = character device, 0 if disk file

¦ ¦ ¦ ¦ ¦ +----- reserved

¦ ¦ ¦ ¦ +------ 1 = media not removable

¦ ¦ ¦ +------ 1 = network device (DOS 3.x+)

¦ ¦ +------ reserved

¦ +------ 1 = supports IOCTL, via functions 2 & 3

+------ reserved

- BIT 7 of register DX can be used to detect if STDIN/STDOUT is

redirected to/from disk; if a call to this function has DX BIT 7

set it's not redirected from/to disk; if it's clear then it is

redirected to/from disk

- BIT B of register DX can be used to determine if a drive is

removable.