INT 21 - DOS 2+ - IOCTL - READ FROM BLOCK DEVICE CONTROL CHANNEL AX = 4404h BL = drive number (00h = default, 01h = A:, etc.) CX = number of bytes to read DS:DX -> buffer Return: CF clear if successful AX = number of bytes actually read CF set on error AX = error code (01h,05h,06h,0Dh) (see #01680 at AH=59h/BX=0000h) Notes: format of data is driver-specific this function was not supported by Digital Research's DOS Plus SeeAlso: AX=4402h"DOS 2+",AX=4405h"DOS",INT 2F/AX=122Bh