Aaeon SBC-555 Manual page 30

You can attach one or two Enhanced Integrated Device Electron-
ics hard disk drives to the SBC-554V/555's internal controller.
The SBC-554V/555's IDE controller uses a PCI local-bus
interface and supports faster data transfer.
Connecting drives is done in a daisy-chain fashion and requires
one of two cables, depending on the drive size. 1.8" and 2.5"
drives need a 1 x 44-pin to 2 x 44-pin flat-cable connector. 3.5"
drives use a 1 x 44-pin to 2 x 40-pin connector.
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. 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.)
Connect a second drive as described above.
Unlike floppy drives, IDE hard drives can connect to either end of
the cable. If you install two drives, you will need to set one as the
master and one as the slave by using jumpers on the drives. If you
install just one drive, set it as the master.