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wozardry

wozardry is a multi-purpose tool for manipulating .woz disk images. It can validate file structure, edit metadata, import and export metadata in JSON format, remove unused tracks, and provides a programmatic interface to "read" bits and nibbles from a disk image. It supports both WOZ 1.0 and WOZ 2.0 files and can convert files from one version to the other.

Installation

wozardry is written in Python 3.

It requires bitarray, which can be installed thusly:

$ pip3 install -U bitarray

(Developers who wish to run the test suite should also install the pytest module with pip3 install -U pytest)

Command line interface

wozardry is primarily designed to be used on the command line to directly manipulate .woz disk images in place. It supports multiple commands, which are listed in the wozardry -h output.

verify command

This command verifies the file structure and metadata of a .woz disk image. It produces no output unless a problem is found.

Sample usage:

$ wozardry verify "WOZ 2.0/DOS 3.3 System Master.woz"

Tip: you can download a collection of .woz test images.

The verify command does not "read" the data on the disk like an emulator would. It merely verifies the structure of the .woz file itself and applies a few sanity checks on the embedded metadata (if any). The disk may or may not boot in an emulator. It may not pass its own copy protection checks. It may not have the data you expected, or any data at all. The verify command can not answer those questions.

dump command

Prints all available information and metadata in a .woz disk image.

Sample usage:

$ wozardry dump "WOZ 2.0/Wings of Fury - Disk 1, Side A.woz"
TMAP:  Track 0.00              TRKS 0
TMAP:  Track 0.25              TRKS 0
TMAP:  Track 0.75              TRKS 1
TMAP:  Track 1.00              TRKS 1
.
. [many lines elided]
.
TMAP:  Track 33.75             TRKS 34
TMAP:  Track 34.00             TRKS 34
TMAP:  Track 34.25             TRKS 34
META:  language:               English
META:  publisher:              Broderbund
META:  developer:
META:  side:                   Disk 1, Side A
META:  copyright:              1987
META:  requires_ram:           128K
META:  subtitle:
META:  image_date:             2018-01-15T01:30:53.025Z
META:  title:                  Wings of Fury
META:  version:
META:  contributor:            DiskBlitz
META:  notes:
META:  side_name:
META:  requires_machine:       2e
META:                          2c
META:                          2e+
META:                          2gs
INFO:  File format version:    2
INFO:  Disk type:              5.25-inch (140K)
INFO:  Write protected:        yes
INFO:  Tracks synchronized:    yes
INFO:  Weakbits cleaned:       yes
INFO:  Creator:                Applesauce v1.1
INFO:  Boot sector format:     1 (16-sector)
INFO:  Optimal bit timing:     32 (standard)
INFO:  Compatible hardware:    2e
INFO:                          2c
INFO:                          2e+
INFO:                          2gs
INFO:  Required RAM:           128K
INFO:  Largest track:          13 blocks

The TMAP section (stands for "track map") shows which tracks are included in the disk image. As you can see from the above sample, the same bitstream data can be assigned to multiple tracks, usually adjacent quarter tracks. Each bitstream is stored only once in the .woz file.

The META section shows any embedded metadata, such as copyright and version. This section is optional; not all .woz files will have the same metadata fields, and some may have none at all.

The INFO section shows information that emulators or other programs might need to know, such as the boot sector format (13- or 16-sector, or both) and whether the disk is write protected. All INFO fields are required and are included in every .woz file.

The output of the dump command is designed to by grep-able, if you're into that kind of thing.

$ wozardry dump "WOZ 2.0/Wings of Fury - Disk 1, Side A.woz" | grep "^INFO"

will show just the INFO section.

Tip: the .woz specification lists the standard metadata fields and the acceptable values of all info fields.

edit command

This command lets you modify any information or metadata field in a .woz file. This is where the fun(*) starts.

(*) not guaranteed, actual fun may vary

The inline help is a good overview.

usage: wozardry edit [-h] [-i INFO] [-m META] file

Edit information and metadata in a .woz disk image

positional arguments:
  file                  .woz disk image (modified in place)

optional arguments:
  -h, --help            show this help message and exit
  -i INFO, --info INFO  change information field. INFO format is "key:value".
                        Acceptable keys are disk_type, write_protected,
                        synchronized, cleaned, creator, version. Additional
                        keys for WOZ2 files are disk_sides, required_ram,
                        boot_sector_format, compatible_hardware,
                        optimal_bit_timing. Other keys are ignored. For
                        boolean fields, use "1" or "true" or "yes" for true,
                        "0" or "false" or "no" for false.
  -m META, --meta META  change metadata field. META format is "key:value".
                        Standard keys are title, subtitle, publisher,
                        developer, copyright, version, language, requires_ram,
                        requires_machine, notes, side, side_name, contributor,
                        image_date. Other keys are allowed.

Tips:

 - Use repeated flags to edit multiple fields at once.
 - Use "key:" with no value to delete a metadata field.
 - Keys are case-sensitive.
 - Some values have format restrictions; read the .woz specification.

Let's look at some examples.

Working with this same "Wings of Fury" disk image, let's give the game author his due by adding the developer metadata field:

$ wozardry edit -m "developer:Steve Waldo" "WOZ 2.0/Wings of Fury - Disk 1, Side A.woz"

Metadata fields are arbitrary; there is a standard set listed in the .woz specification, but you can add your own.

$ wozardry edit -m "genre:action" -m "perspective:side view" "WOZ 2.0/Wings of Fury - Disk 1, Side A.woz"

You can use a similar syntax to remove metadata fields that don't apply to this disk.

$ wozardry edit -m "version:" -m "notes:" -m "side_name:" -m "subtitle:" "WOZ 2.0/Wings of Fury - Disk 1, Side A.woz"

Now let's look at that metadata section again:

$ wozardry dump "WOZ 2.0/Wings of Fury - Disk 1, Side A.woz" | grep "^META"
META:  language:               English
META:  publisher:              Broderbund
META:  developer:              Steve Waldo
META:  side:                   Disk 1, Side A
META:  copyright:              1987
META:  requires_ram:           128K
META:  image_date:             2018-01-15T01:30:53.025Z
META:  title:                  Wings of Fury
META:  contributor:            DiskBlitz
META:  requires_machine:       2e
META:                          2c
META:                          2e+
META:                          2gs
META:  genre:                  action
META:  perspective:            side view

You can modify INFO fields using a similar syntax (-i instead of -m), but be aware that INFO fields are highly constrained, and incorrect values can have noticeable effects in emulators. wozardry will reject any values that are nonsensical or out of range, but even in-range values can render the disk image unbootable. For example, the "optimal bit timing" field specifies the rate at which bits appear in the floppy drive data latch; if the rate is not what the disk's low-level RWTS code is expecting, the disk may be unable to read itself.

Nonetheless, here are some examples of changing INFO fields. To tell emulators that a disk is not write-protected, set the write_protected field to no, false, or 0.

$ wozardry edit -i "write_protected:no" "WOZ 2.0/Wings of Fury - Disk 1, Side A.woz"

To tell emulators that the disk only runs on certain Apple II models, set the compatible_hardware field with a pipe-separated list. (Values may appear in any order. See kRequiresMachine in the wozardry source code for all the acceptable values.)

$ wozardry edit -i "compatible_hardware:2e|2e+|2c|2gs" "WOZ 2.0/Wings of Fury - Disk 1, Side A.woz"

How to convert WOZ1 to WOZ2 files

As of this writing, the .woz specification has undergone one major revision, which changed the internal structure of a .woz file and added several new INFO fields. Both file formats use the .woz file extension; they are distinguished by magic bytes (WOZ1 vs. WOZ2) within the file.

Let's say you have an older WOZ1 file, like this one from the WOZ 1.0 directory of the official test images collection:

$ wozardry dump "WOZ 1.0/Wings of Fury - Disk 1, Side A.woz" | grep "^INFO"
INFO:  File format version:    1
INFO:  Disk type:              5.25-inch (140K)
INFO:  Write protected:        yes
INFO:  Tracks synchronized:    yes
INFO:  Weakbits cleaned:       yes
INFO:  Creator:                Applesauce v0.29

The "file format version" confirms this is a WOZ1 file. To convert it to a WOZ2 file, set the version field to 2.

$ wozardry edit -i "version:2" "WOZ 1.0/Wings of Fury - Disk 1, Side A.woz"

$ wozardry dump "WOZ 1.0/Wings of Fury - Disk 1, Side A.woz" | grep "^INFO"
INFO:  File format version:    2
INFO:  Disk type:              5.25-inch (140K)
INFO:  Write protected:        yes
INFO:  Tracks synchronized:    yes
INFO:  Weakbits cleaned:       yes
INFO:  Creator:                Applesauce v0.29
INFO:  Boot sector format:     0 (unknown)
INFO:  Optimal bit timing:     32 (standard)
INFO:  Compatible hardware:    unknown
INFO:  Required RAM:           unknown
INFO:  Largest track:          13 blocks

All the new (v2-specific) INFO fields are initialized with default values. Existing fields like the write-protected flag are retained. ("Largest track" is a calculated field and can not be set directly.)

import and export commands

These commands allow you to access the information and metadata in a .woz file in JSON format.

$ wozardry export "WOZ 2.0/Wings of Fury - Disk 1, Side A.woz"
{
  "woz": {
    "info": {
      "version": 2,
      "disk_type": 1,
      "write_protected": true,
      "synchronized": true,
      "cleaned": true,
      "creator": "Applesauce v1.1",
      "disk_sides": 1,
      "boot_sector_format": 1,
      "optimal_bit_timing": 32,
      "compatible_hardware": [
        "2e",
        "2c",
        "2e+",
        "2gs"
      ],
      "required_ram": 128,
      "largest_track": 13
    },
    "meta": {
      "language": "English",
      "publisher": "Broderbund",
      "developer": [
        ""
      ],
      "side": "Disk 1, Side A",
      "copyright": "1987",
      "requires_ram": "128K",
      "subtitle": [
        ""
      ],
      "image_date": "2018-01-15T01:30:53.025Z",
      "title": "Wings of Fury",
      "version": [
        ""
      ],
      "contributor": "DiskBlitz",
      "notes": [
        ""
      ],
      "side_name": [
        ""
      ],
      "requires_machine": [
        "2e",
        "2c",
        "2e+",
        "2gs"
      ]
    }
  }
}

You can pipe the output of the export command to the import command to copy metadata from one .woz file to another.

$ wozardry export game-side-a.woz | wozardry import game-side-b.woz

Technically, this merges metadata. All metadata fields in game-side-a.woz will be copied to game-side-b.woz, overwriting any existing values for those fields. But if game-side-b.woz already had additional metadata fields that were not present in game-side-a.woz, those will be retained.

Tip: a2rchery is a tool to manipulate .a2r flux images. These .a2r files can also have embedded metadata, just like .woz files. And guess what! a2rchery also has import and export commands, just like wozardry. You see where this is going.

$ wozardry export game.woz | a2rchery import game.a2r

remove command

This command allow you to remove one or more tracks from a .woz disk image.

Tracks are specified in quarter tracks, in base 10 (not base 16). Multiple tracks can be removed at once.

$ wozardry remove -t0.25 -t0.5 -t0.75 -t1 -t1.25 -t35 "Gamma Goblins.woz"

Note: tracks are stored as indices in the TMAP chunk, and multiple tracks can refer to the same bitstream (stored in the TRKS chunk). If you remove all tracks that refer to a bitstream, the bitstream will be removed from the TRKS chunk and all the indices in the TMAP chunk will be adjusted accordingly.

Python interface

WozDiskImage interface

This represents a single WOZ disk image. You can create it from scratch, load it from a file on disk, or parse it from a bytestream in memory.

>>> import wozardry
>>> woz_image = wozardry.WozDiskImage()
>>> woz_image.woz_version
2

This newly created woz_image already has an info dictionary with all the required fields in the INFO chunk.

>>> from pprint import pprint
>>> pprint(woz_image.info)
OrderedDict([('version', 2),
             ('disk_type', 1),
             ('write_protected', False),
             ('synchronized', False),
             ('cleaned', False),
             ('creator', 'wozardry 2.0-beta'),
             ('disk_sides', 1),
             ('boot_sector_format', 0),
             ('optimal_bit_timing', 32),
             ('compatible_hardware', []),
             ('required_ram', 0)])
>>> woz_image.info["compatible_hardware"] = ["2", "2+"]
>>> woz_image.info["compatible_hardware"]
['2', '2+']

It also has an empty meta dictionary for metadata.

>>> pprint(woz_image.meta)
OrderedDict()
>>> woz_image.meta["copyright"] = "1981"
>>> woz_image.meta["developer"] = "Chuckles"
>>> pprint(woz_image.meta)
OrderedDict([('copyright', '1981'),
             ('developer', 'Chuckles')])

How to load and save files on disk

To load a .woz disk image from a file (or any file-like object), open the file and pass it to the WozDiskImage constructor. Be sure to open files in binary mode.

>>> with open("Wings of Fury.woz", "rb") as fp:
...     woz_image = wozardry.WozDiskImage(fp)

To save a file, serialize the WozDiskImage object with the bytes() method and write that to disk. Be sure to open files in binary mode.

>>> with open("Wings of Fury.woz", "wb") as fp:
...     fp.write(bytes(woz_image))

Track interface

A .woz disk image usually contains multiple tracks of data, otherwise what's the point, right? Each track is accessed by the Track interface.

The WozDiskImage.seek() returns a Track object that contains that track's data (or None if that track is not in the disk image).

Tip: the seek() method takes a logical track number, which could be a quarter track or half track. To get the data on track 1.5, call seek(1.5).

In this example, we load a .woz image from disk and seek to track 0:

>>> with open("Wings of Fury.woz", "rb") as fp:
...     woz_image = wozardry.WozDiskImage(fp)
>>> tr = woz_image.seek(0)
>>> tr
<wozardry.Track object at 0x108ccf3c8>

Now we can access the bitstream of the track. The raw bitstream is in tr.bits, but you probably want to use one of these convenience methods instead.

To search the track for a specific nibble sequence, use the find() method. It returns True if the nibble sequence was found, or False otherwise.

>>> tr.find(bytes.fromhex("D5 AA 96"))
True

The Track object maintains state of where it is within the bitstream (tr.bit_index), including wrapping around to the beginning if it reaches the end (tr.revolutions). After finding that D5 AA 96 nibble sequence with the find() method, we can read the next nibbles in the bitstream with the nibble() generator.

>>> hex(next(tr.nibble()))
'0xff'
>>> hex(next(tr.nibble()))
'0xfe'
>>> hex(next(tr.nibble()))
'0xaa'
>>> hex(next(tr.nibble()))
'0xaa'
>>> hex(next(tr.nibble()))
'0xab'
>>> hex(next(tr.nibble()))
'0xaa'

Tip: the nibble() generator returns nibbles like a real disk controller. 0 bits between nibbles are ignored, so the high bit of the returned nibble is always 1. The find() method uses the nibble() generator internally, so it also ignores 0 bits between nibbles.

If you want to read individual bits from the current position in the bitstream, use the bit() generator.

>>> next(tr.bit())
1
>>> next(tr.bit())
1
>>> next(tr.bit())
1
>>> next(tr.bit())
1
>>> next(tr.bit())
1
>>> next(tr.bit())
1
>>> next(tr.bit())
1
>>> next(tr.bit())
0

Unlike a real disk controller, you can move backwards in the bitstream, allowing you to speculatively look at bits then rewind as if you hadn't seen them yet.

Let's rewind as if we hadn't just read those 8 individual bits, then read them as a nibble:

>>> tr.rewind(8)
>>> hex(next(tr.nibble()))
'0xfe'

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A multi-purpose tool for manipulating .woz disk images

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