the first pattern from the disk medium and writes the segments of the second pattern onto the disk medium and fills and empties the buffers in a complementary manner in accordance with step 238 this process corresponds to fig3 5 the complementary operation of the buffers must be understood as referring to the overall operation of the buffers and not to a condition that is necessarily maintained instantaneously at all times in the illustrated embodiment during the recording onto alternate segments the record buffer is filled by the encoder at 5 megabits second the chosen output rate of the encoder if the total write to disk bit rate capability is 11 megabits second as described then the record buffer is being emptied at a net 6 megabits second due to the difference between the filling and emptying rates during the writing operation the track buffer is being emptied at 5 megabits second the same rate as the decoding rate both buffers are being emptied so instantaneously the sum of the number of segments in both buffers is decreasing after the segment is written to the disk a segment is read from the disk and written into the track buffer also at 11 megabits second as described the track buffer is being emptied at 5 megabits second accordingly when the disk is being read the track buffer is being filled at a net 6 megabits second due to the difference between the filling and emptying rates during the reading operation the record buffer is being filled at 5 megabits second.