Default at f000:efc7
        db      step rate & head unload times
        db      head load time & DMA
        db      motor off time
        db      sector size (0->128, 1->256, 2->512, 3->1024)
        db      last sector number (8 or 9 typical)
        db      inter-sector gap size on read/write (42 typical)
        db      data transfer length (255 typical)
        db      inter-sector gap size on format (80 typical)
        db      sector fill on format (f6 typical)
        db      head-settle time ms (typical 25, 2.10->15)
        db      motor start-up time (1/8 secs) (typical 4, 2.10->2)
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