The 7500 shipped with a 601-100 and no cache in the slot, if you found a 604E then it is from another machine (but will still work, 604EV will not). ROM is built in and cannot be changed. For VRAM you need 2 sticks or 4 sticks (must be in pairs, each stick is 1MB), RAM I think is 8MB minimum per stick, 8 slots to fill 1 at a time, or in matched pairs for a little speed boost.