SAMdisk — FAQ

Can I use a USB floppy drive?

No. Standard USB floppy drives contain a separate floppy controller chip, which is not directly accessible from the host PC. Without that access it’s not possible to support formats beyond what the drive chooses to expose (usually 720K and 1.44M formats only).

However, there are a number of advanced USB-based floppy projects in development, which give extremely low-level access to floppy media. Support for such devices will be considered in the future.

What type of disks are supported?

Most PC-compatible soft-sectored disks should work, without prior knowledge of the format. If there’s an existing DOS/Linux utility for them, you should have no problems. If in doubt, scan the disks and see what shows up.

The PC floppy controller is quite limited compared to some other chips (particularly the WD17xx) and full track-level control. Consequently, there are problem areas that cannot be supported:

• Only FM and MFM disks are supported. For Amiga disks, try adfread instead.
• Copy protections for systems using more flexible controllers (such as the Atari ST) will usually be far beyond what the PC can handle. However, standard format disks for such system will usually work fine.
• Sectors positioned too close to the index hole cannot be accessed at all. This is known to affect some TRS-80 and BetaDisk (TR-DOS) disks, where there is insufficient gap4a padding at the start of the track. Disks that aren’t index-synchronised (including some 8-bit Atari formats) may also be affected by this. SAMdisk will usually warn if it suspects the first sector is missing, and supports use of an index-halving cable to give access them.

Will a GUI be added?

Probably, but only for basic reading and writing tasks. Core functionality remains higher priority than a GUI, so advanced features are likely to remain command-line only.

Will there be versions for Linux and macOS?

Yes, but initially supporting only disk image and hard disk functions.

Limited floppy access may be added to Linux later, using the fdrawcmd ioctl interface. It lacks the special short-write functionality provided by fdrawcmd.sys, and without it the following can’t be written correctly:

• Sectors with ID header CRC error.
• Sectors with ID header but missing data field.
• Sectors with data CRC error and specific contents.
• Sectors with gap data following the data field (CPC).
• Weak sectors (+3/CPC).
• 8K sectors with 6K valid data (+3/CPC).
• Sega System 24 (1.8M and 1.88M).

Looking further ahead, these may be supported on all platforms using flux-level USB devices such as the KryoFlux and DiscFerret.