double density (DD,2D)

Bits written on the IBM Diskette 2D at twice the density used on IBM Diskette 1 and 2。; 以兩倍于IBM軟盤1和軟盤2的密度將二進制位寫在IBM軟盤2D上。參閱IBM,Diskette 1, Diskette 2,Diskette 2D。