: FD@
    2 * 16 + ( blkfs starts at sector 16 )
    0x0201 BLK( 2 PICK _
    0x0201 BLK( 0x200 + ROT 1+ _ ;
: FD!
    2 * 16 + ( blkfs starts at sector 16 )
    0x0301 BLK( 2 PICK _
    0x0301 BLK( 0x200 + ROT 1+ _ ;
: FD$
    ( get number of sectors per track with command 08H. )
    0x03 ( boot drive ) C@ 13H08H
    8 RSHIFT 1+ FDHEADS C!
    0x3f AND FDSPT C!
;