INT 21,44,1 / IOCTL,1 - Set Device Information

AH = 44h

AL = 01

BX = handle

DH = must be zero

DL = device data low order byte (see below)

on return

AX = error code if CF set

DX = device information (see below)

- applicable to character devices only

- allows setting of device data word for character devices

- usually used to change from binary to translated I/O

- handle in BX must be an opened file or device