IBM F50 RS/6000 7025 - Manual (Page 174)

Installing Adapters
Adding an adapter, such as audio, communication, or specialized graphics, extends
the capabilities and power of your system. Your system has nine
expansion slots for
connecting adapters. The expansion slots are numbered on the back of the system
as shown below. You can install ISA and PCI adapters.
Memory adapters cannot be installed in your system because it does not support
channel memory.
5-30 IBM RS/6000 7025 F50 Series User's Guide