SHADDR
data_addr = ahd_inq(ahd, SHADDR);
ahd_outq(ahd, SCB_DATAPTR, ahd_inq(ahd, SHADDR));
ahd_inl(ahd, SHADDR+4),
ahd_inl(ahd, SHADDR),
data_addr = ahc_inl(ahc, SHADDR);