INT 21,44 - I/O Control for Devices (IOCTL)

% Standard Call Format

AH = 44h

AL = function value

BX = file handle

BL = logical device number (0=default, 1=A:, 2=B:, 3=C:, ...)

CX = number of bytes to read or write

DS:DX = data or buffer

on return:

AX = error code if CF set

AX = # of bytes transferred if CF not set

% For more information, see the following topics:

~IOCTL,0~ Get Device Information

~IOCTL,1~ Set Device Information

~IOCTL,2~ Read From Character Device

~IOCTL,3~ Write to Character Device

~IOCTL,4~ Read From Block Device

~IOCTL,5~ Write to Block Device

~IOCTL,6~ Get Input Status

~IOCTL,7~ Get Output Status

~IOCTL,8~ Device Removable Query

~IOCTL,9~ Device Local or Remote Query

~IOCTL,A~ Handle Local or Remote Query

~IOCTL,B~ Set Sharing Retry Count

~IOCTL,C~ Generic I/O for Handles

~IOCTL,D~ Generic I/O for Block Devices (3.2+)

~IOCTL,E~ Get Logical Drive (3.2+)

~IOCTL,F~ Set Logical Drive (3.2+)

- see: ~DEVICE COMMAND CODES~

~DEVICE REQUEST HEADER~

~DEVICE STATUS~

~DEVICE HEADER~

~DEVICE ATTRIBUTES~