What is a .dsk file?

A .dsk file is a DiskDup image, an exact copy (sector by sector) of a floppy disk. DSK images were a popular format for cloning or duplicating 1980's and 1990's Macintosh floppy disks.

 

How to use or extract DSK images contents?

DSK images are mountable and writeable/clonable onto real floppy disks.  Tough, remember that if you want to write a DSK image onto a real floppy disk using a Windows PC floppy drive, it may not work properly, because Apple floppy drives had special firmware allowing them to write an additionnal amount of kilobytes on a given floppy disk.  PC floppy disks could hold 360KB (or 720KB for double density) while Macs could hold 400KB (or 800KB for double density).

You can also mount, browse and extract files from DSK images using various disk image tools under Mac OS.  Mounting a .dsk file makes a new drive appear on your OS, effectively letting you use it as if you had the original media inserted.

DSK images can also be attached to many emulators since it was a popular floppy disk archiving format.  Namely, Mini vMac supports direct drag and drop of DSK images onto the virtual machine window.  It will mount as it were a real floppy disk on the emulated desktop.

 

Under emulators

Mini vMac and Mini vMac II: Just drag and drop the file onto the emulator's window and it will immediately attempt to mount it.

Basilisk II: Under Settings > Volumes tab > Add... choose the .dsk file and restart the emulator.  It will mount after Mac OS is booted.

SheepShaver: Under Settings > Volumes tab > Add... choose the .dsk file and restart the emulator.  It will mount after Mac OS is booted.

 

Under Classic Mac OS (before Mac OS X)

Mac OS 8.6 to Mac OS 9.2.2: Mount the disk image using Toast 5 Titanium

System 7.1 to Mac OS 9.2.2: Write .dsk to real floppy disks or mount as virtual disk using ShrinkWrap

System 6.0 to System 7.6: Write .dsk to real floppy disks using DiskDup

 

Under Mac OS X

OSX 10.0 to 10.5: If a regular 1.4MB floppy disk image (not 400KB MFS or 800KB HFS) use Disk Utility: FILE menu > Open disk image...

OSX 10.6 to 10.14: Same as above but it will be read only, cannot write or format HFS volumes anymore.

macOS 10.15 and newer: You can't and one should not even have to mount .dsk in macOS anyway. Mount them in an emulator instead.

Note: Under some versions of Mac OS X where double clicking the .dsk file did nothing except to launch Disk Utility, renaming the .dsk file so that it ends with .img will enable it to auto-mount when double clicked.

 

Under Windows

Open it using HFVExplorer to browse and extract SOME of the files, altough be warned that any file having a resource fork will be destroyed if you export it out to a Windows disk partition. Alternatively, PowerISO also reads most of the HFS disk images.