TR-DOS disk specs v1.0 - last revised on 9-28-1997

- Max disk sides are 2
- Max logical tracks per side are 80
- Logical sectors per track are 16
- Sector dimension is 256 bytes
- Root directory is 8 sectors long starting from track 0, sector 1
- Max root entries are 128
- Root entry dimension is 16 bytes
- Logical sector 8 (9th physical) holds disc info
- Logical sectors from 0 to 15 are unused
- Files are *NOT* fragmented

Directory entry structure:

------------------------------------------------------------------------------
Offset | Length | Description
------------------------------------------------------------------------------
  00   |    7   | file name (*)
  08   |    1   | file extension
  09   |    2   | file start address
  11   |    2   | file length in bytes
  13   |    1   | file length in sectors
  14   |    1   | starting sector on disk
  15   |    1   | starting tack on disk
------------------------------------------------------------------------------
(*) If first byte is 1h then the file is deleted


Logical sector 8 structure:

------------------------------------------------------------------------------
Offset | Lenght | Description
------------------------------------------------------------------------------
  000  |   1    | 0 - signals end of root directory
  001  |  224   | unused (filled by 0)
  225  |   1    | number of first free sector on disk
  226  |   1    | the number of track of first free sector on disk
  227  |   1    | disk type
  228  |   1    | number of files on disk
  229  |   2    | number of free sectors on disk
  231  |   1    | TR-DOS ID byte (always 10h - 16 dec)
  232  |   1    | unused (filled by 0)
  233  |   9    | unused (filled by 20h - 32 dec)
  243  |   1    | unused (filled by 0)
  244  |   1    | number of deleted files on disk
  245  |   8    | disk label (8 chars)
  253  |   3    | end of disk info (filled by 0)
------------------------------------------------------------------------------
(*) Byte at offset 227 could be one of the following:

    16h : 80 tracks, double sided
    17h : 40 tracks, double sided
    18h : 80 tracks, single sided
    19h : 40 tracks, single sided