Function 4404h (68-4)    IOCTL: Read from Block Device

Reads a control string from a block device.

On entry:      AH         44h
AL         04h
BL         Drive number (0=default, 1=A, etc.)
CX         Number of bytes to read
DS:DX      Data or buffer

Returns:       AX         Number of bytes read
Error code, if CF is set

Error codes:   1          Device doesn't support control strings
5          Drive is invalid

                                                                          

This subfunction reads CX bytes of data from the block device's
control channel into either DS:DX or the memory pointed to by DS:DX.
How data is written is defined by the device driver.  Data can be read
only if the device can process control strings.

See also: 44h
See also: 4405h

4404h (68-4) IOCTL: Read from Block Device