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

2018/09/07 07:04 · prokushev

Int 21H, AH=37H, AL=03H


2.x and 3.3+ only


set availdev flag

Family API


      AH = 37h
      AL = 03h set availdev flag
              DL = new state
                  00h         \DEV\ is mandatory
                  nonzero     \DEV\ is optional


AL = status

          00h successful
          FFh unsupported subfunction



all versions of DOS from 2.00 allow \DEV\ to be prepended to device
        names without generating an error even if the directory \DEV does
        not actually exist (other paths generate an error if they do not
        exist); DOS 2.x has an AVAILDEV= option in CONFIG.SYS to make \DEV
      although MS-DOS 3.3+, DR DOS 3.41+, and Novell DOS 7 accept these
        calls, they have no effect, and AL=02h always returns DL=FFh (except
        for Novell DOS 7, which leaves AX unchanged for both subfunctions)

See also



Process manager INT 20H, INT 21H: 00H, 25H, 26H, 31H, 34H, 35H, 4CH, INT 22H, INT 27H, INT 28H
File manager INT 25H, INT 26H, INT 21H: 0DH, 0EH, 0FH, 10H, 11H, 12H, 13H, 14H, 15H, 16H, 17H, 19H, 1AH, 1BH, 1CH, 21H, 22H, 23H, 24H, 27H, 28H, 29H, 2EH, 2FH, 32H, 3305H, 36H
Character Device I/O INT 29H, INT 21H: 01H, 02H, 03H, 04H, 05H, 06H, 07H, 08H, 09H, 0AH, 0BH, 0AH, 0CH
Signals INT 23H, INT 24H, INT 21H: 3300H, 3301H, 3302H
Memory manager
Date and Time INT 21H: 2AH, 2BH, 2CH, 2DH
Misc INT 21H: 30H, 3306H, 3700H, 3701H, 3702H, 3703H
NLS INT 21H: 3303H, 3304H
2018/09/04 19:23 · prokushev

en/docs/dos/api/int21/37/03.txt · Last modified: 2020/12/14 11:06 by prokushev