Copy That Floppy: A Guide to Preserving Data from Fragile Floppy Disks

The Copy That Floppy guide establishes a standardized workflow for practitioners to create disk images of fragile floppy disks for long-term preservation. By focusing on flux-level imaging rather than simple file extraction, the methodology ensures that non-standard formats, copy-protection schemes, and degraded magnetic signals are captured in their rawest form, allowing for future re-interpretation as decoding technology improves.

Identifying Floppy Disk Carriers

Accurate identification of the physical media is the prerequisite for selecting the correct hardware. The guide covers four primary sizes: 8-inch, 5.25-inch, 3.5-inch, and 3-inch disks.

Key Identification Markers

• 3.5-inch Disks: High Density (HD) disks typically feature two holes on the bottom and an "HD" label; Double Density (DD) disks usually have only one hole.
• 5.25-inch Disks: These can be harder to distinguish, but some DD disks feature a colored hub ring. "Flippy" disks (single-sided disks modified with an extra notch to allow writing on both sides) are common in legacy collections.
• Hard Sectored Disks: Found in 8-inch and 5.25-inch formats, these are identifiable by multiple index holes.
• Labels: Labels indicating SS (Single-Sided), DS (Double-Sided), SD (Single Density), DD (Double Density), or HD (High Density) provide a starting point, though the guide warns that labels can be misleading due to the historical practice of reusing expensive disks.

Hardware Acquisition and Configuration

Preservation requires a combination of a compatible floppy disk drive, a specialized floppy controller, and the correct power and cabling interfaces.

Drive Selection by Format

• 8-inch: Shugart Associates SA800/801 (single-sided) or SA850/851 (double-sided) are recommended for their robustness. Low-voltage power supplies (typically 24V) are preferred over internal mains voltage models for safety.
• 5.25-inch: An 80-track high-density (1.2 MB) drive is the most versatile, as its narrower heads can typically read 40-track FM/MFM media. TEAC (FD-55 series) and EPSON drives are noted for durability.
• 3-inch: Used primarily in Amstrad and Schneider systems. 720 KB drives are preferred as they are backward compatible with 360 KB disks.
• 3.5-inch: Internal HD drives are recommended over USB floppy drives. USB drives are unsuitable for archival work because they lack access to flux-level data and often ignore write-protection tabs, potentially allowing modern operating systems to write "System Volume Information" to the disk.
• Apple-Specific Hardware: Apple II (5.25-inch) and early Macintosh (3.5-inch) disks often use variable spindle speeds and GCR encoding. For these, the Applesauce controller paired with native Apple drives (e.g., Disk II or Superdrive) is the recommended best practice.

Floppy Controllers for Preservation

Modern preservation controllers capture raw magnetic flux transitions rather than interpreting sectors and files.

• Greaseweazle: An affordable, open-source, command-line based controller widely used for various formats.
• Applesauce: Specifically recommended for Apple-formatted disks due to its ability to handle unique Apple hardware quirks.
• Kryoflux: A commercial flux-level controller compatible with Windows, Linux, and macOS.
• Other Options: The FC5025 (5.25-inch only, no flux stream), FluxEngine (DIY, provides direct filesystem access), and Catweasel (legacy PCI-based) are also available.

Cabling and Power Requirements

• Standard Interfaces: Most 3.5-inch and 5.25-inch drives use 34-pin Shugart interfaces. 3-inch drives require 26-pin cables, and 8-inch drives use 50-pin connectors (often requiring 50-to-34 pin adapters).
• Power: 3.5-inch drives typically need 5V (4-pin floppy connector), while 5.25-inch drives require 12V (Molex). 8-inch drives may require complex regulated power supplies up to 24V.

Maintenance, Cleaning, and Testing

Because legacy hardware is prone to mechanical failure and contamination, rigorous maintenance is required to prevent the "bulldozer effect," where dirty heads push contaminants across the disk surface, causing permanent damage.

Drive Maintenance

• Cleaning: Read/write heads should be cleaned using dedicated head-cleaning diskettes or by direct application of 70-99% isopropyl alcohol with a non-abrasive tool (e.g., a credit card edge).
• Mechanical Repair: Common failures include degraded rubber drive belts, which can be replaced. Hardened pinch rollers or eject pads may be cleaned with isopropyl alcohol or replaced with 3D-printed parts.
• Lubrication: Dried factory grease on guide rails should be cleaned and replaced with a minimal amount of plastic-safe silicone grease or light synthetic oil.

Disk Cleaning and Inspection

• Inspection: Disks should be held at an angle under bright light to check for mould, dust, or warping. A "squealing" sound during a read attempt is a primary indicator that a disk requires cleaning.
• Cleaning Methods: Light contamination can be treated with non-ionic surfactant soap and distilled water on a lint-free cloth, wiping in a circular motion from the hub outward. Severe mould contamination may require opening the disk jacket and cleaning the magnetic media in a soapy bath, followed by air drying and re-insertion into a donor jacket.

The Imaging Workflow

The goal of the imaging process is to create a flux-level representation of the disk before attempting to convert it into a usable file system.

Flux Stream Capture

A flux stream records the raw magnetic transitions without interpreting them as data.

• Greaseweazle can output RAW (individual files per track) or SuperCard Pro (SCP) formats. RAW is preferred for damaged disks as it allows practitioners to stitch together the best reads from multiple identical disks.
• Applesauce uses a dedicated macOS app to capture A2R flux formats, which can be converted to other types.

Analysis and Troubleshooting

Captured flux streams are analyzed using tools like the HxC Floppy Emulator software, Fluxfox, or DiskImageTool.

• Visual Indicators: In HxC, green indicates a successful capture, while red bands may indicate missing tracks (common when reading 40-track disks on 80-track drives) or intentionally malformed sectors used for copy protection.
• Anomalies: Flux imaging is particularly useful for detecting "upformatted" disks (e.g., 1.68MB or 2MB disks) and disks with mixed encoding (e.g., 8-inch disks with FM boot tracks and MFM data tracks).

Conversion and File Access

Once a flux stream is verified, it is converted into a structured disk image (e.g., IMG, HFE). Tools for accessing the resulting files include 7-Zip, FTK Imager, HFSExplorer, and WinImage. For executable content, the EaaSI project provides a comprehensive overview of compatible emulators.