Fold the Atari ST writer into write ibm. Update documentation.

doc/disk-acornadfs.md

@@ -35,4 +35,5 @@ fluxengine read adfs
 ```
 
 You should end up with an `adfs.img` of the appropriate size for your disk
-format.
+format. This is an alias for `fluxengine read ibm` with preconfigured
+parameters.

doc/disk-acorndfs.md

@@ -23,4 +23,5 @@ fluxengine read dfs
 ```
 
 You should end up with an `dfs.img` of the appropriate size for your disk
-format.
+format. This is an alias for `fluxengine read ibm` with preconfigured
+parameters.

doc/disk-ampro.md

@@ -23,7 +23,8 @@ fluxengine read ampro
 ```
 
 You should end up with an `ampro.img` which is 409600 or 819200 bytes long.
-You can pass this straight into [cpmtools](http://www.moria.de/~michael/cpmtools/):
+This is an alias for `fluxengine read ibm` with preconfigured parameters.  You
+can pass this straight into [cpmtools](http://www.moria.de/~michael/cpmtools/):
 
 ```
 $ cpmls -f ampdsdd ampro.img

doc/disk-atarist.md

@@ -14,7 +14,8 @@ Just do:
     fluxengine read atarist
 
 ...and you'll end up with an `atarist.st` file. The size of the disk image will
-vary depending on the format.
+vary depending on the format. This is an alias for `fluxengine read ibm` with
+preconfigured parameters.
 
 Writing disks
 -------------
@@ -23,51 +24,39 @@ FluxEngine can also write Atari ST scheme disks.
 
 The syntax is:
 
-    fluxengine write atarist -i input.st <options>
+    fluxengine write ibm -i input.st <options>
 
-The format of `input.st` will vary depending on the kind of disk you're writing,
-which is configured by the options. By default FluxEngine will write an 80
-track, 9 sector, double-sided disk. If that doesn't match your target format you
-will need to pass some options. There are some presets, which you will almost
-certainly want to use if possible:
+The format of `input.st` will vary depending on the kind of disk you're
+writing, which is configured by the options.  You will almost certainly need to
+pass one of these:
 
-  - `--st-preset-360`: a 360kB 3.5" disk, with 80 cylinders,
-  1 side, and 9 sectors per track.
-  - `--st-preset-370`: a 370kB 3.5" disk, with 82 cylinders,
-  1 side, and 9 sectors per track.
-  - `--st-preset-400`: a 400kB 3.5" disk, with 80 cylinders,
-  1 side, and 10 sectors per track.
-  - `--st-preset-410`: a 410kB 3.5" disk, with 82 cylinders,
-  1 side, and 10 sectors per track.
-  - `--st-preset-720`: a 720kB 3.5" disk, with 80 cylinders,
-  2 sides, and 9 sectors per track.
-  - `--st-preset-740`: a 740kB 3.5" disk, with 82 cylinders,
-  2 sides, and 9 sectors per track.
-  - `--st-preset-800`: a 800kB 3.5" disk, with 80 cylinders,
-  2 sides, and 10 sectors per track.
-  - `--st-preset-820`: a 820kB 3.5" disk, with 82 cylinders,
-  2 sides, and 10 sectors per track.
+  - `--ibm-preset-atarist-360`: a 360kB 3.5" disk, with 80 cylinders, 1 side,
+	and 9 sectors per track.
+  - `--ibm-preset-atarist-370`: a 370kB 3.5" disk, with 82 cylinders, 1 side,
+	and 9 sectors per track.
+  - `--ibm-preset-atarist-400`: a 400kB 3.5" disk, with 80 cylinders, 1 side,
+	and 10 sectors per track.
+  - `--ibm-preset-atarist-410`: a 410kB 3.5" disk, with 82 cylinders, 1 side,
+	and 10 sectors per track.
+  - `--ibm-preset-atarist-720`: a 720kB 3.5" disk, with 80 cylinders, 2 sides,
+	and 9 sectors per track.
+  - `--ibm-preset-atarist-740`: a 740kB 3.5" disk, with 82 cylinders, 2 sides,
+	and 9 sectors per track.
+  - `--ibm-preset-atarist-800`: a 800kB 3.5" disk, with 80 cylinders, 2 sides,
+	and 10 sectors per track.
+  - `--ibm-preset-atarist-820`: a 820kB 3.5" disk, with 82 cylinders, 2 sides,
+	and 10 sectors per track.
 
-These options simply preset the output destination flag (`-d`) and the
-following, lower-level options. Note that options are processed left to right,
-so it's possible to use a preset and then change some settings. To see the
-values for a preset, simply append `--help`.
-  - `--st-sector-size=N`: the size of a sector, in bytes. Must be a power of
-  two.
-  - `--st-gap1-bytes=N`: the size of gap 1 in bytes (between the IAM record
-  and the first sector record).
-  - `--st-gap2-bytes=N`: the size of gap 2 in bytes (between each sector
-  record and the data record).
-  - `--st-gap3-bytes=N`: the size of gap 3 in bytes (between the data record
-  and the next sector record).
-  - `--st-sector-skew=0123...`: a string representing the order in which to
-  write sectors: each character represents on sector, with `0` being the
-  first. Sectors 10 and above are represented as letters from `A` up.
+See [the IBM format documentation](disk-ibm.md) for more information.
 
 
 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 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
+  - [Atari ST Floppy Drive Software
+	Information](https://info-coach.fr/atari/software/FD-Soft.php) by Jean
+	Louis-Guerin