are replied with a sequence of data packets,
each of them must be ACK'ed by the host.

<P>
Command 0 must be issued with a 4 byte argument containg the new value
for the register (bytes in "LSB first" order).  Command 2 typically is
issued with a single zero byte as an argument.  Command 3 is issued with
an argument of variable number of bytes.  If this is a printable string,
it should <B>not</B> include the trailing zero byte.

<P>
Camera replies to the command 1 with a single data packet contai