disks 22 can be partitioned into circumferential zones take advantage of the additional recording area that becomes available as heads 28 move from the inner diameter of disk 22 to the outer diameter accordingly disk 22 is partitioned into the inner recording zone 38 and the outer recording zone 39 inner zone 38 is comprised of 7 sectors per track and outer zone 39 is comprised of 14 sectors per track in practice magnetic disks are typically partitioned into many recording zones sometimes as many zones as there are tracks the present invention is operable with any number of recording zones fig3 illustrates the data channel layout of the preferred embodiment of the present invention during a write operation preamble data 40 and sync mark 42 from a data generator 104 followed by a source data sequence 49 and ecc bytes 46 are written to hda 20 source data 49 enters double attribute method dam encoder 102 where it is encoded as a series of data symbols b n 54 according to a mission dependent modulation look up table 100 the preferred embodiment of which is illustrated in fig4 a 6 a and 6 b symbols b n 54 output from dam encoder 102 are converted into write symbols a n 56 by a non return to zero nrz current pulse modulator 106 write circuitry 108 responsive to the symbols a n 56 modulates the current in the recording portion of read write head 28 fig1 at a predetermined baud rate.