Epson EQUITY 3865X/20 PLUS - Manual (Page 116)

7. Determine which cable is the hard disk drive cable and
which is the diskette drive cable.
Both the diskette drive and hard disk drive sockets on the
main system board have a notch on one side. The hard disk
drive socket is closest to the front of the main system board
and the diskette drive socket is behind it.
8. Connect the diskette drive cable first. As shown below,
there is a tab on one side of the connector.
diskette drive connector
diskette drive socket
notch
Align the connector with the socket so the tab on the
connector lines up with the notch in the socket. Make sure
the holes in the connector fit over all the pins in the socket
and then push in the connector.
Accessing
Internal Components 5-13