NEC POWERMATE PRO2180 Manual page 112

ISA expansion slots support industry-standard 8-bit or 16-
bit expansion boards. The PCI/ISA slot also supports PCI
expansion boards.
PCI expansion boards run at the system's processor speed.
The PCI bus handles 32 bits of data at a time, being wider
as well as faster than the standard ISA bus. PCI boards can
send and receive data much faster which boosts system
performance.
Locating expansion slots
Installing Options 5-9