en:docs:dos:api:int21:44:09

Note: This API call is for DOS personality only. Use Family API for portability.

2018/09/07 07:04 · prokushev

Int 21H, AH=44H, AL=09H

Version

3.1 and higher

Brief

CHECK IF BLOCK DEVICE REMOTE

Family API

Input

AX = 4409h
BL = drive number (00h = default, 01h = A:, etc)

Return

CF clear if successful

    DX = device attribute word
	bit 15: drive is SUBSTituted
	bit 13: (DR DOS 3.41/5.0 local drives only) always set
		media ID needed
	bit 12: drive is remote
	bit  9: direct I/O not allowed
CF set on error
    AX = error code (01h,0Fh,15h) (see #01680 at AH=59h/BX=0000h)

Macro

Notes

on local drives, DX bits not listed above are the attribute word from
  the device driver header (see #01646 at AH=52h); for remote drives,
  the other bits appear to be undefined for MS-DOS versions prior to
  5.0 (they are all cleared in DOS 5+)
checking whether DX=0800h on return appears to be a fairly reliable
  method for detecting Microsoft's RAMDRIVE, though not for other
  ramdisks (there appears to be no simple yet foolproof method for
  detecting ramdisks, although the presence of only a single copy of
  the FAT and only a single head on non-removable devices is a fairly
  good indicator); for Windows95, RAMDRIVE returns DX=4800h
for non-existent remote drives, this function sometimes returns
  AX=0015h (drive not ready) instead of AX=000Fh (invalid drive) on
  the first call; a subsequent call will return the correct error
  code
this function was not supported by Digital Research's DOS Plus

See also

AX=4400h,AX=4408h,AX=440Ah,INT 2F/AX=122Bh

Note


en/docs/dos/api/int21/44/09.txt · Last modified: 2021/05/01 14:56 by prokushev