DD - Double-Density.Double-density disks have twice as much storage space per unit area than the outdated single-density format, but have less storage space than high-density disks.Double-density 3.5" floppy disks are 720k DOS, 800k Mac, and have 2DD written on them.Double-density 5.25" floppies have a 360k capacity; дс тдрлими цюлютдажкию дроемжки аиакиохдйис лидр http://www.computeruser.com/resources/dictionary/definition.html;
