Disk Specification

Summary

• Disk
  • Each 64DD disk contains 2 sides, and each side a total of 1175 cylinder tracks over 8 different zones.
  • A track is also composed of 2 blocks, made of 90 sectors each, 85 user data sectors, 4 C2 error correction sectors, and 1 gap sector (unused by the driver).
  • Each zone has a different sector size.
  • C1 error correction data for each sector is 7 bytes. This may not be outputted by the drive.
• Official Driver Process
  • The driver considers that each zone has a total of 12 defective tracks.
  • For seek optimizations, the ordering of the blocks is interleaved between each track.
    • LBA 0 = Track 0 Block 0 / LBA 1 = Track 0 Block 1
    • LBA 2 = Track 1 Block 1 / LBA 3 = Track 1 Block 0
      Notice the swapped order in Track 1.
  • Side 0 is read in one direction, while Side 1 is read in the other direction.

Disk Zones

Amount of tracks, including defects

	Side 0	Side 1
Zone 0	158
Zone 1	158	158
Zone 2	149	158
Zone 3	149	149
Zone 4	149	149
Zone 5	149	149
Zone 6	149	149
Zone 7	114	149
Zone 8		114

Sector Byte Size in each zone

	Size
Zone 0	232
Zone 1	216
Zone 2	208
Zone 3	192
Zone 4	176
Zone 5	160
Zone 6	144
Zone 7	128
Zone 8	112