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Copyright 1991 David Jurgens |
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.
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| Esc or Alt-X to exit |
int 21,44,0 |
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