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fluxengine/doc/disk-atarist.md
2022-02-16 22:06:26 +01:00

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Disk: Atari ST
==============
Atari ST disks are standard MFM encoded IBM scheme disks without an IAM header.
Disks are typically formatted 512 bytes per sector with between 9-10 (sometimes
11!) sectors per track and 80-82 tracks per side.
For some reason, occasionally formatting software will put an extra IDAM record
with a sector number of 66 on a disk, which can horribly confuse things. The
Atari profiles below are configured to ignore these.
Be aware that many PC drives (including mine) won't do the 82 track formats.
Reading disks
-------------
Just do:
fluxengine read <format>
...and you'll end up with an `atarist.st` file. The size of the disk image will
vary depending on the format. This is an alias for `fluxengine read ibm` with
preconfigured parameters.
Note that the profile by default assumes a double-sided disk; if you're reading
a single-sided disk, add `--heads 0` to prevent FluxEngine from looking at the
other side and getting confused by any data it sees there.
Writing disks
-------------
FluxEngine can also write Atari ST scheme disks.
The syntax is:
fluxengine write <format> -i input.st
Available formats
-----------------
`<format>` can be one of these:
- `atarist360`: a 360kB 3.5" disk, with 80 cylinders, 1 side, and 9 sectors
per track.
- `atarist370`: a 370kB 3.5" disk, with 82 cylinders, 1 side, and 9 sectors
per track.
- `atarist400`: a 400kB 3.5" disk, with 80 cylinders, 1 side, and 10 sectors
per track.
- `atarist410`: a 410kB 3.5" disk, with 82 cylinders, 1 side, and 10 sectors
per track.
- `atarist720`: a 720kB 3.5" disk, with 80 cylinders, 2 sides, and 9 sectors
per track.
- `atarist740`: a 740kB 3.5" disk, with 82 cylinders, 2 sides, and 9 sectors
per track.
- `atarist800`: a 800kB 3.5" disk, with 80 cylinders, 2 sides, and 10 sectors
per track.
- `atarist820`: a 820kB 3.5" disk, with 82 cylinders, 2 sides, and 10 sectors
per track.
See [the IBM format documentation](disk-ibm.md) for more information. Note that
only some PC 3.5" floppy disk drives are capable of seeking to the 82nd track.
Useful references
-----------------
- [Atari ST Floppy Drive Hardware
Information](https://info-coach.fr/atari/hardware/FD-Hard.php) by Jean
Louis-Guerin
- [Atari ST Floppy Drive Software
Information](https://info-coach.fr/atari/software/FD-Soft.php) by Jean
Louis-Guerin