Aaeon SBC-555 Manual page 31

You can attach up to two floppy disks to the SBC-554V/555 on-
board controller. You can use any combination of 5¼" (360 KB
and 1.2 MB) and/or 3½" (720 KB, 1.44 MB, and 2.88 MB) drives.
A 34-pin daisy-chain drive connector cable is required for a dual-
drive system. On one end of the cable is a 34-pin flat-cable
connector. On the other end are two sets of floppy disk drive
connectors. Each set consists of a 34-pin flat-cable connector
(usually used for 3½" drives) and a printed-circuit board connec-
tor (usually used for 5¼" drives).
1. Plug the 34-pin flat-cable connector into CN2. Make sure that
the red wire corresponds to pin one on the connector.
2. Attach the appropriate connector on the other end of the cable
to the floppy drive(s). You can use only one connector in the
set. The set on the end (after the twist in the cable) connects
to the A: drive. The set in the middle connects to the B: drive.
3. If you are connecting a 5¼" floppy drive, line up the slot in the
printed circuit board with the blocked-off part of the cable
connector.
If you are connecting a 3½" floppy drive, you may have trouble
determining which pin is pin number one. Look for a number
printed on the circuit board indicating pin number one. Also,
the connector on the floppy drive connector may have a slot.
When the slot is up, pin number one should be on the right.
Check the documentation that came with the drive for more
information.
If you desire, connect the B: drive to the connectors in the
middle of the cable as described above.