Magnetic Disk

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The 64DD reads data stored on magnetic disks that use a proprietary logical layout.

Logical Layout

Disks are composed of:

  • 2 Heads.
  • 1175 Tracks per Head.
  • 2 Blocks per Track.
  • 90 Sectors per Block. (85 Data Sectors, 4 C2 Sectors, and 1 Gap Sector.)

However, only Data Sectors are present in disk dumps.

Sector size varies depending on the Zone:

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















Zone range varies depending on the Head:

Head # Zone Range
0 Zone 0 - Zone 7
1 Zone 1 - Zone 8






System Area

yes

User Area