If the SD card is blank, copy the entire "romdata" folder onto the SD card.
If the card already contains the "romdata" folder, copy the "M187" folder onto the card.
If the card already contains folders up to "M187", copy the necessary firmware files (e.g. M187xxxx.fwu) into this folder.
Do not put multiple machine firmware programs on the same SD card. Copy the only model firmware you want.