IBM S85 pSeries 680 Service Manual page 45

Note: In an RS/6000 SP environment, there is normally a cable attached from this
port to the SP Control Workstation. To directly attach a TTY terminal to this
port, the cable to the SP Control Workstation must be disconnected. Be
sure to reconnect this cable after servicing the system.
17. Operator panel (OP) connector
18. RIO 0 and RIO 1
19. Power cord connector for left power supply
20. Left power supply, power good LED
21. Fans (mounted on front end of left power supply)
22. Left power supply
* Serial ports 1 and 2 can only be used for service processor menus. No "heartbeat-"
type devices can be used on these ports.
Chapter 1. Reference Information
23