IBM RS/6000 - Manual (Page 46)

Figure 9. RS/6000 Model E20 Front View
Slots
Eight slots are available which can accommodate the following adapters types:
Five slots for PCI adapters
Two slots for ISA adapters
One shared slot that can accommodate either a PCI or an ISA adapter
Integrated SCSI-2 adapter
The system comes standard with an integrated PCI-based internal SCSI-2 fast/wide
controller that can be used for internal SCSI-2 devices only. You can have all
narrow, all fast/wide or a combination of both SCSI-2 types on the internal SCSI-2
bus.
Standard I/O ports
The system provides the following standard I/O ports:
Keyboard port - The IBM Enhanced Keyboard, an optional feature on the Model
E20
Mouse port - Port provided to support an optional three-button mouse
Two 9-pin D-shell serial connectors for external RS232 access
One 25-pin parallel port that maintains complete compatibility with ISA, EISA
and microchannel parallel ports
22 Introduction to PCI-Based RS/6000 Servers