Function  44h   I/O Control for Devices (IOCTL)  Get or Set Device Information


entry   AH      44h 

	AL	0Fh	Set Logical Device (DOS 3.3+)

	BL      drive number:  0=default, 1=A:, 2=B:, etc. 

	BX      file handle 

	CX      number of bytes to read or write 

	DS:DX   data or buffer 

	DX      data 

return  AX      number of bytes transferred 

		or error code (call function 59h for extended error codes) 

		or status  00h     not ready 

			   0FFh    ready 

	CF	set if error