These are the commands used by the Morley board. *LO and *HI set which banks of ROMs on the board are to appear in the ROM table, and *LBOARD gives a listing of the ROMs available on the board.

The difficulty with Master series ROM expansion boards is that a choice is always made of which ROMs on the expansion board can actually be used at any one time. This is because the BBC Master architecture already has provision for all 16 ROM slots to be available. On an unexpanded BBC Model B, various ROM slots are not available due to hardware limitations so a ROM board can fill all the gaps. With the Master series arrangements, a trade-off is made which usually involves losing access to the sideways RAM.

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