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Utility to manage file systems on retro computer disk images

Project description

Python library for hierarchical filesystem parsing on Atari 8-bit and Apple ][ disk images. The successor to atrcopy, this is under heavy development and is still in a beta state. It is the basis for disk image support in Omnivore 2.

Pronounced “uh-trip”, the name is a happy coincidence that a dictionary word exists that is the quasi-portmanteau of “ATR” (the Atari 8 bit disk image container) & “rip” (extracting stuff from images). The actual word is a nautical term: “atrip” as in “the anchor is atrip”, meaning the ship’s anchor is off the bottom. I have no particular affinity for ships, but that I had some justification in the portmanteau is enough for me.



Supported Python versions:

  • Python 3.6 (and later)

Runtime Dependencies

  • numpy
  • jsonpickle
  • lz4

It will be automatically installed when installing with pip as described below.

Development Dependencies

  • pytest
  • pytest-cov (optional)

The test suite uses pytest and pytest-cov, but these are not required for normal installation.


ATRip is available in the PyPI and installable using pip:

pip install atrip

Linux and macOS note: if numpy needs to be installed on your system, it may be compiled from source which can take several minutes.


  • list contents of disk images
  • copy files to and from disk images
  • delete files from disk images
  • create new disk images
  • concatenate binary data together into a file on the disk image
  • compile assembly source into binary files if pyatasm is installed

Supported Formats

Supported Disk Image Types

  • XFD: XFormer images, basically raw disk dumps
  • ATR: Nick Kennedy’s disk image format; includes 16 byte header
  • DCM: Disk Communicator images, Bob Puff’s compression format for Atari disk images
  • CAS: Atari cassette images
  • DSK: Apple ][ DOS 3.3 disk image; raw sector dump

Supported File System Formats

File System Platform Read Write Status
DOS 2 (90K) Atari 8-bit Yes Yes Fully supported
DOS 2 (180K) Atari 8-bit Yes Yes Fully supported
DOS 2.5 (130K) Atari 8-bit Yes Yes Fully supported
DOS 3 (130K) Atari 8-bit No No Unimplemented
SpartaDOS Atari 8-bit No No Under development
MyDOS Atari 8-bit Partial No Under development
DOS 3.3 Apple ][ Yes Yes Fully supported
ProDOS 8 Apple ][ No No Unimplemented

Other Supported Formats

Format Platform/description Read Write Status
.xex Atari 8-bit executable files Yes Yes Fully supported
KBoot Atari 8-bit xex in boot disk Yes Yes Fully supported
.car Atari 8-bit cartridge images Yes No Read only
BSAVE Apple ][ BSAVE data Yes Yes Fully supported

Note: Atari ROM cartridges are supported in both both plain binary and atari800 .car format


Archives containing multiple disk images are supported, where each disk image within the archive will be given a disk number and is addressable using that prefix.

Container File Ext Read Write Status
Zip File .zip Yes Yes Fully supported
Tar File .tar Yes Yes Fully supported

Archives may also be compressed with any of the general purpose compression formats listed below.

Supported Compression Formats

Compression is supported transparently, so any type of disk image compressed with any of the following formats can be used directly, without first decompressing it before running ATRip.

Chaining is supported to an arbitrary depth, meaning that one compression algorithm can be applied to the output of another. This is not practical except in limited cases, as in a Disk Communicator image that is subsequently gzipped (image.dcm.gz). But cases that actually make compression worse will be handled as well, like image.gz.bz2.xz.bz2.gz.gz.gz.

Compression Format File Ext Read Write Status
gzip .gz Yes Yes Fully supported
bzip2 .bz2 Yes Yes Fully supported
lzma .xz, .lzma Yes Yes Fully supported
lzw (Unix compress) .Z Yes No Read only [1]
lz4 .lz4 Yes Yes Fully supported
Disk Communicator .dcm Yes Yes Atari images only [2]
[1]Contains code from the BSD-licensed python implementation of Mark Adler’s reference C implementation of unlzw. See LICENSE.unlzw in the source distribution for more details.
[2]Not general purpose compression; Atari 720 or 1040 sector disk images only. Contains my own python reimplementation of the DCM algorithms based on the GPL code in acvt

Segment Structure

Collection:      example.atr: plain file
Container:          D1: 92176 bytes, compression=none
Header:                 ATR Header (16 bytes)
DiskImage:              Atari SD (90K) Floppy Disk Image, size=92160, filesystem=Atari DOS 2
BootSegment:                Boot Sectors (384 bytes)
Segment:                        Boot Header (6 bytes)
Segment:                        Boot Code (378 bytes @ 0006)
VTOC:                       DOS2 SD VTOC (128 bytes)
Directory:                  Directory (1024 bytes)
Dirent:                         File #0  (.2.u. ) 004 DOS     SYS  035
FileType:                           DOS.SYS (4375 bytes) Unknown file type
Dirent:                         File #1  (.2.u. ) 039 DUP     SYS  054
AtariObjectFile:                    DUP.SYS (6708 bytes) Atari 8-bit Object File
ObjSegment:                             Segment #1 (6706 bytes)
Segment:                                    [$2949-$4376] (6702 bytes)


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