HelpPC 2.10 Quick Reference Utility 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.

Esc or Alt-X to exit int 21,44,0 Home/PgUp/PgDn/End ←↑↓→
Converted to HTML in 2006 by Timo Bingmann