no. PROM is not an expansion slot.
it satnds for Programmable read only memory.
ISAC
expansion slot
MCA
MCA
To play 3 or 4 players on Hydro Thunder you need a Expansion Pak in your expansion slot.
Heat expansion.
The expansion slot is the socket on the motherboard that can hold an adapter card. There are different types of expansion slots (pci, pcie, pciex16) so you need to check that the expansion is the same kind as the adapter card.
An obsolete slot for voice-modems I think
motion
AGP
expansion slots are found on the motherboard
FYI