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Fix & Document Apple II sector mapping

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* Update documentation (note apple flux writing is a unicorn now even though this isn't quite true until #489)
 * Fix DOS 3.3 mapping
 * Add ProDOS (all versions) mapping
This commit is contained in:
Jeff Epler
2022-03-08 08:39:43 -06:00
parent e9286f6ae9
commit 3c305e8a37
5 changed files with 59 additions and 25 deletions
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32
doc/disk-apple2.md
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@@ -2,7 +2,7 @@ Disk: Apple II
==============
Apple II disks are nominally fairly sensible 40-track, single-sided, 256
bytes-per-sector jobs. However, they come in two varieties: DOS 3.3 and
bytes-per-sector jobs. However, they come in two varieties: DOS 3.3/ProDOS and
above, and pre-DOS 3.3. They use different GCR encoding systems, dubbed
6-and-2 and 5-and-3, and are mutually incompatible (although in some rare
cases you can mix 6-and-2 and 5-and-3 sectors on the same disk).
@@ -21,14 +21,14 @@ This means that Apple II disks can do all kinds of weird things, including
having spiral tracks! Copy protection for the Apple II was even madder than
on other systems.
FluxEngine can only read well-behaved, DOS 3.3 6-and-2 disks. It doesn't even
try to handle the weird stuff.
FluxEngine can only read well-behaved 6-and-2 disks. It doesn't even try to
handle the weird stuff.
Sadly, DOS 3.3 also applies logical sector remapping on top of the physical
sector numbering on the disk, and this _varies_ depending on what the disk is
for. FluxEngine doesn't attempt to remap sectors, instead giving you an exact
copy of what's on the disk, so you may need to do some work before the images
are usable in emulators.
Apple DOS also applies logical sector remapping on top of the physical sector
numbering on the disk, and this _varies_ depending on what the disk is for.
FluxEngine can remap the sectors from physical to logical using modifiers. If
you don't specify a remapping modifier, you get the sectors in the order they
appear on the disk.
Reading discs
@@ -41,9 +41,13 @@ fluxengine read apple2
```
You should end up with an `apple2.img` which is 143360 bytes long.
It will be in physical sector ordering. You can specify a sector ordering,
`appledos` or `prodos` to get an image intended for use in an emulator,
due to the logical sector mapping issue described above:
**Big warning!** The image may not work in an emulator, due to the
logical sector mapping issue described above.
```
fluxengine read apple2 prodos
```
Writing discs
-------------
@@ -53,8 +57,12 @@ Just do:
fluxengine write apple2 -i apple2.img
```
**Big warning!** An image designed for an emulator may not work, due to the
logical sector mapping issue described above.
If your image is in logical sector ordering (images intended for emulators
usually are), specify a modifier of `appledos` or `prodos`:
```
fluxengine write apple2 prodos -i apple2.img
```
Useful references