DM9000_NCR
iow(db, DM9000_NCR, NCR_RST | NCR_MAC_LBK);
if (ior(db, DM9000_NCR) & 1)
iow(db, DM9000_NCR, 0);
iow(db, DM9000_NCR, NCR_RST | NCR_MAC_LBK);
if (ior(db, DM9000_NCR) & 1)
unsigned ncr = dm9000_read_locked(db, DM9000_NCR);
iow(db, DM9000_NCR, ncr);