Aaeon SBC-400 User Manual page 26

You can attach two Enhanced Integrated Device Electronics hard
disk drives to the SBC-400's internal controller. The card comes
with a 40-pin flat-cable piggyback cable. This cable has three
identical 40-pin flat-cable connectors.
Wire number 1 on the cable is red or blue, and the other wires are
gray.
1. Connect one end of the cable to CN1 on the CPU card. Make
sure that the red (or blue) wire corresponds to pin 1 on the
connector, which is labeled on the board (on the right side).
2. Plug the other end of the cable to the Enhanced IDE hard drive,
with pin 1 on the cable corresponding to pin 1 on the hard
drive. (See your hard drive's documentation for the location of
the connector.)
Unlike floppy drives, you can make the connections with any of the
connectors on the cable. If you install two drives, you will need to
set one as the master and one as the slave. You do this using