: _  ( dstaddr blkno -- )
    [ SDC_DEVID LITN ] (spie)
    0x51 ( CMD17 ) 0 ROT ( a cmd 0 blkno ) _cmd
    IF _err THEN
    _wait 0xfe = NOT IF _err THEN
    0 SWAP               ( crc a )
    512 0 DO             ( crc a )
        _idle            ( crc a n )
        DUP ROT C!+      ( crc n a+1 )
        ROT> _crc16      ( a+1 crc )
        SWAP             ( crc a+1 )
    LOOP
    DROP                 ( crc1 )
    _idle 8 LSHIFT _idle +  ( crc2 )
    _wait DROP 0 (spie)
    = NOT IF _err THEN ;