: _sdc@  ( dstaddr blkno -- )
    _sdcSel 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 )
        DUP _idle        ( crc a a n )
        DUP ROT C!       ( crc a n )
        ROT SWAP _crc16  ( a crc )
        SWAP 1+          ( crc a+1 )
    LOOP
    DROP                 ( crc1 )
    _idle 8 LSHIFT _idle +  ( crc2 )
    _wait DROP _sdcDesel
    = NOT IF _err THEN ;
