No that's something else, LoROM and HiROM differ in how the ROM data is mapped into memory, while FastROM and SlowROM differ in the bus speed. You can have Lo/S

No that's something else, LoROM and HiROM differ in how the ROM data is mapped into memory, while FastROM and SlowROM differ in the bus speed. You can have Lo/Slow, Lo/Fast, Hi/Slow or Hi/Fast carts.