This page presents several Atari Floppy Disks image's formats. These images can be used for emulation or for preservation backup / copy of original Atari floppy disks. Some of these formats can be used directly (for example Pasti STX) in hardware / software emulators while some other may require to be converted (for example Kryoflux Stream files) by program like Aufit.
Disk Image formats presentation
Disk images are mainly used by SW or HW emulators. There are a lot of sites dedicated to the subject of Atari emulation and I will therefore point you to a list of links on the subject.
The major disk image formats used by the Atari emulators are:
- ST : Supported by all emulators, it is the most simple format since it’s a straight copy of the readable data of a disk. Created originally for the PacifiST emulator, it does not allow copying copy-protected disks.
- MSA : An acronym for Magic Shadow Archiver, it is a format created on Atari by the compression program of the same name. This format, is also supported by almost all emulators. It contains the same data as the ST format, the only difference is that the data is compressed. A variation of the program on Atari allows saving the data without any compression. This result in an ST file but with an MSA header. A nice feature of the MSA program is that it allows to split an archive into multiple files, thus facilitating the transfer of large disk images on floppies.
- DIM : A format created by the well known Atari copy program: "FastCopy Pro". The non-compressed version of this format contains the same information as the ST and MSA formats, but with a proprietary header. This format is also supported by most emulators.
- STT : Created and developed by the creators of Steem SSE Engine emulator, it is supposed to allow the copy of many original disks, including certain copy-protected games. It supports disks of various numbers of tracks that can be of different size as well as other details. For example it supports irregular sector numbers, sector numbers in range $F7-FF and 1 KB sectors.
- STX: Defined by the PASTI initiative (Atari ST Imaging & Preservation Tools). The Pasti imaging tools can virtually create images of any ST disk including copy protected disks. The STX Images can be used by the Steem SSE, SainT, and Hatari emulators. It is also supported by the HxC FD Emulator.
- IPF: Defined by the Software Preservation Society (SPS). -- Currently only SPS can create IPF files from stream files generated with the KryoFlux board. The IPF format supports images of most ST disk including copy protected disks. The IPF Images can be used by the Steem SSE, SainT, and Hatari emulators. It is also supported by the HxC FD Emulator. It can also be used to create backup copy of original floppy disk.
- CTR: Created by the Software Preservation Society (SPS). -- The CTR files are generated with the KryoFlux board. The CTR format support images of any ST disk including copy protected disks. The CTR Images can be used by the Steem SSE, and Hatari emulators. It is also supported by the HxC FD Emulator. It can be used to create copy of original floppy disk.
- Raw: The raw stream files are created by the KryoFLux board. This format is an image of the Floppy Disk at the flux transition level. It provides very detailed information. The raw stream files can be converted to IPF format by SPS people . You cannot use it directly in a SW emulator it needs to be converted to a format supported by the emulator.
- SCP: Created by the SuperCard Pro board. This format is an image of the Floppy Disk at the flux transition level. It provides very detailed information and can be used directly to create a backup floppy disk (even protected one). It is directly supported by Steem SSE and HxC FD Emulator. When not directly supported (for example in Hatari) you can use my Aufit Program to convert to STX.
- STG: Steem SSE ST Gost format
- STW: Steam ST Write format see Atari-Forum or Specification
- HFE: from HxC2001 project see Specification
Note also that most recent emulators like Steem SSE can directly read zipped disk images. For example Steem SSE or Hatari can mount directly a zipped file (.zip) that contains a disk image of any of the supported disk image format.
Recently Steem SSE andBack to the top
The following table summurize the supported formats for each emulators:
|SD HxC||Yes||Yes||Yes||Yes||No VBR||No VBR||Yes||Yes||Yes|
Back to the top
This section try to answer the question: I have Atari floppies that I want to use with my favorite emulator...
- Making ST Disk Images (Only on a PC):
To make ST images on a Windows system the best solution is to use the Floppy Imaging & File transfer (FloImg) program from P. Putnik.Historical programs Makedisk (DOS), imgbuild (DOS), wfdcopy (Windows 95/98 you will have problem on XP/7).
- Making MSA Images (On PC and Atari ST):
To make MSA images on a Windows system the best solution is to use the Floppy Imaging & File transfer (FloImg) program from P. Putnik. On Atari I have made the tests with MSA II - V2.3. The process is straightforward : start the program specify the name and directory for the image, indicate if you want the file to be compressed or not and click the "Disk -> File" button ... and you are done. You should use compressed mode to get smaller disk images.
- Making DIM Disk Image (On Atari ST):
First you need the FastCopy Pro version (version "no version", or 1.0 or 1.2 did work for me). Important if you are using the version "without version" number you must first select the "all" option from the get sectors choice, in V1.0 and 1.2 this choice is unavailable (always pre-selected to all). After that you need to click on the "image copy" button, then select the "read" button and enter the name of the file you want to create... This file should be directly readable by the emulators.
- Making STT Disk Images (On PC or Atari ST):
To make STT images on a Windows system the best solution is to use the Floppy Imaging & File transfer (FloImg) program from P. Putnik. On Atari use the STeem Disk Imager that comes with STeem itself. Instructions are provided in the disk image howto.txt file. The STT image can be mounted by STeem only.
- Making STX Disk Images of copy protected disk (On Atari ST):
Instruction is provided with the Pasti imaging program.
- Making IPF Disk Images (By SPS people only):
At this time only SPS people can create IPF files.
- Making CTR Disk images (different platforms):
Instruction is provided with the Kryoflux software
- Making RAW Disk images (different platforms):
Instruction is provided with the Kryoflux software
- Making SCP Disk images (different platforms):
Instruction is provided with the SCP imaging program.
This section try to answer the question: I have some interesting disk images and I would like to create a FD to run on my real Atari...
- Making a floppy disk from a ST image (Only on PC):
On a Windows system the best solution is to use the Floppy Imaging & File transfer (FloImg) program from P. Putnik to write ST images on an actual FD. Historical programs makedisk (DOS), or ST Disk (DOS), or wfdcopy (Windows 95/98 you will have problem on Windows XP / 7 / 8).
- Making a floppy disk from a MSA image (On PC or Atari ST):
On a Windows system the best solution is to use the Floppy Imaging & File transfer (FloImg) program from P. Putnik to write ST images on an actual FD. I have made the tests with MSA II - V2.3. The process is straightforward : start the program specify the name and directory of the image, click the "File -> Disk" button ... and you should have your disk ready.
- Making a floppy disk from a DIM image (On Atari ST):
First you need the FastCopy Pro version (version "no version", or 1.0 or 1.2). you need to click on the "image copy" button, then select the "Restore" button and enter the name of the image file...
- Making a floppy disk from a STT image (on PC or Atari ST):
This is only possible if no protection or specific protections have been used. Your best choice is to use the Floppy Imaging & File transfer (FloImg) program from P. Putnik. In some cases (when no protection are used) it is possible to first convert the STT image to an ST or MSA image using the MSA converter program, and from this converted image use one of the procedure described above.
- Making a floppy disk from a STX image:
It is not possible to create a protected disk from an STX image. The main reason is that protected disk uses specific data that cannot be written directly by the Atari FD controller.
- Making a floppy disk from a IPF / CTR / RAW image:
Described in the KryoFlux Project and the KryoFlux Board
- Making a floppy disk from a SCP image:
Described in the SCP project.
As already mentioned above, if you deal with disk images there is one program you must have: the Floppy Imaging & File transfer program (FloImg) from P. Putnik. This program can be used to create images in ST / MSA / STT format directly from a ST floppy placed in the PC Floppy Drive. It is also possible to create FD directly from images. It also support ST <-> to MSA conversion.
Another must have program is the MSA converter that run under Windows. This program not only allow conversion between different image formats but it also gives useful information about the image content.
My Aufit program can be used to convert Kryoflux RAW, or Supercard Pro SCP images to STX, ST, or MSA format.
For information there are some historical programs that run under DOS for st to msa conversion or from msa to st conversion. As well as two DOS programs to convert a PC disk to/from an ST disk.
All these formats are relatively simple and are described in my documentBack to the top
The Pasti format is the most widely used format for emulation as it provides a good support of protected disk. Almost any floppy disks can be imaged using this format and it is supported by STeem, and Hatari emulators. It is also supported by the HxC2001 HW Floppy Emulator.
Unfortunately Ijor, the creator, has not published information about the STX format. However several people have reversed engineered and described this format. You can find information in Markus Fritze page, in P.Putnik page, and information from the HxC2001 software (pasti loader).
I have written a complete documentation about the Pasti file format. This documentation is based on the above information as well as email discussion with Ijor. I have also written a small program to read and write Pasti file. The reader display detail information about the data and metatdata inside a Pasti file. Along with the documentation it can help to understand the Pasti file format. The Pasti Reader/Writer is part of the public domain Air project (Atari Image fileReader-Writer).Back to the top
The IPF (Interchangeable Preservation Format) is a file format created by SPS (Software Preservation Society). It is used to preserve the content of old floppy disks for many platforms. IPF files are created by SPS people by analyzing stream files created with the Kryoflux Hardware. The IPF file format reader project has been made public under MAME license. This was done by releasing the source code of a library called the IPF/CAPS library. Unfortunately the actual content of the IPF file has not been documented by SPS people and the only way to understand it was to interpret the released source code that allow to read an IPF file. This is not felt as a problem by most user as the content of IPF files is supposed to be read through the IPF decoder library and written only by SPS people. But for those that want to better understand the format I have created a documentation of the IPF file format. This can be useful just for the sake of understanding the format as well as for people that want to read or write IPF file directly.
The following document provides a description of the IPF Files content (as read by IPF Library v5.1) produced by the SPS people using the CTA Analyzer program. The document also provides assistance on Decoding or Encoding IPF Files. It is based on my understanding of the IPF documentations published by Software Preservation Society but it also includes information based on experimentations and programing. I want to thanks István Fabián and Keir Fraser from SPS who have provided to me with a lot of detailed information about the IPF file (see All you always wanted to know about IPF in the Kryoflux forum).
I have also written a small program to read and write IPF file. The reader display detail information about the data and metatdata inside an IPF file. Along with the documentation it can help to understand the IPF file format. The IPF Reader/Writer is part of the public domain Air project (Atari Image fileReader-Writer).
- Interchangeable Preservation Format (IPF) Documentation
- CAPS Library and API Documentation
- The Air Project
However beware that the information presented in the IPF documents comes from different sources and inevitably must contain errors and therefore must be used with caution. If you only need to read IPF files you should use the IPF library that will be be updated if the format of the file is changed.Back to the top
The following document provides a description of the Stream Files content (as produced by firmware 2.0) produced by the DTC (Disk Tool Console) program connected to a KryoFlux Device. The document also provides assistance on Decoding or Encoding Stream Files. It is based on my understanding of the KryoFlux documentations published by Software Preservation Society and KryoFlux Product & Services Limited but it also includes information based on experimentations and programing (using sources provided by SPS). I want to thanks István Fabián from SPS who has provided to me with a lot of detailed information on how KryoFlux device operates and on the source code used to decode a Stream File.
Note: Regular user of the KryoFlux device should not be concerned by the information presented in this document which is mainly of interest to programmers that want to write tools around the Stream Files.
- Disk Image from Wikipedia
- IPF Library Source Code Released
- All you always wanted to know about IPF
- IPF creation and disk writing via Kryoflux
- CAPS Library and API Documentation Revision 1.02
- SPS WIP: Time for an even more generic way to describe disk formats...
- SPS WIP: Analyzer: Generic MFM Support - Gap Analyzer
- SPS WIP: Analyzer: Generic MFM Support - Gap
- CAPS Source Code Release 4.2
- Amiga Disk Utilities & IPF creation and disk writing via KryoFlux by Keir Fraser
- Structure of descriptors and data for a track by Keir Fraser
- Atari Protection based on Key Disk by Jean Louis-Guerin
- Questions Regarding STT Images
- Protected Disk Image Project Seeking Beta Tester
- Ideas about ST floppy image make program for PC
- PASTI Project
- Pasti File Format
- Atari Protected Disk Image Format & Atari Protected Disk Image Format
- Software Preservation Society (SPS) - originally Amiga but now support Atari
- floppy disk format
- Disk Backup Programs: Do they realy work
- Atari Disk Image FAQ