Kryoflux
Flux-level disk preservation
A USB-based floppy disk controller that captures raw magnetic flux transitions, enabling preservation of copy-protected and deteriorating disks that standard methods cannot read.
Kryoflux is a USB-based floppy disk controller designed for preservation. Unlike standard disk controllers that read formatted data, Kryoflux captures raw magnetic flux transitions, preserving copy-protected disks and recovering data from deteriorating media that would otherwise be lost.
Fast facts
- Released: 2009
- Developer: Software Preservation Society
- Purpose: Archival disk imaging
- Method: Flux-level capture
- Status: Available for purchase
How it works
| Standard Controllers | Kryoflux |
|---|---|
| Read formatted sectors | Capture raw flux |
| Fail on protection | Preserve protection |
| Binary data only | Raw flux, from which a format description is derived |
| Skip bad sectors | Capture everything |
What gets preserved, and what is thrown away
The flux capture is the input, not the artefact. In the SPS workflow the raw signal goes into an analyser “where known disk formats are semi-automatically detected”, and what is saved is an IPF file holding “the disk data, how it is stored (and hence how to write it back), and also a few other things needed to store copy protection (like how dense the data is at any part of each track)”.
That is a subtler thing than a flux dump, and it cuts against the assumption that preservation means keeping every measurement. IPF deliberately throws the measurements away:
the timing information measured by the preservation tool is not stored but the “format description” can for example indicate that specific sectors of a track use a well-known bit-cell density variation. The result is therefore perfect as the timings are not subject to [measurement error]
Recognising the scheme beats recording the symptoms: a description regenerates exact timings, where a recording only ever approximates them.
⚠ One caveat on the format itself. The IPF decoder source was eventually released under the MAME licence, so “the IPF format is now open but unfortunately completely undocumented” — files are meant to be read through the library and “written only by SPS people”. The document cited here is an independent reconstruction, and its author warns it “inevitably must contain errors”.
Key Capabilities
| Capability | Benefit |
|---|---|
| Flux capture | Raw magnetic transitions |
| Copy protection | Preserves timing-based schemes |
| Weak sectors | Multiple reads for recovery |
| Various formats | Amiga, PC, C64, many others |
Preservation Applications
| Use | Value |
|---|---|
| Protected games | Preserve with protection intact |
| Deteriorating media | Rescue before loss |
| Archival | Complete flux record |
| Analysis | Study protection schemes |
Supported Systems
Kryoflux reads disks from:
- Amiga (880KB, HD)
- PC (360KB, 720KB, 1.44MB)
- C64/128 (1541, 1571)
- Atari ST
- Many others
Output Formats
| Format | Use |
|---|---|
| Stream files | Raw flux data |
| IPF | Interchangeable Preservation Format |
| Standard images | ADF, D64, DSK, etc. |
Software Preservation Society
Kryoflux was developed by the SPS:
- IPF format creators
- TOSEC collaboration
- Preservation methodology
- Protected game archives
Legacy
Kryoflux enabled preservation of thousands of protected disks that would otherwise be lost. Its flux-level approach set the standard for archival disk imaging.