HEATHROW_MBCR
MACIO_BIC(HEATHROW_MBCR, 0x04000000);
MACIO_BIS(HEATHROW_MBCR, 0x04000000);
(void)MACIO_IN32(HEATHROW_MBCR);
return (MB_IN32(bay, HEATHROW_MBCR) >> 12) & 7;
MB_BIC(bay, HEATHROW_MBCR, 0x00000F00);