Dual format
Dual format is a technique used to allow two completely different systems software to reside on the same disk.

The term was used on the Amiga and Atari ST platform to indicate that the disk could be inserted into either machine and it would still boot and run. The secret behind this lies in a very special layout of the first track of the disk which contained an Amiga and an Atari ST bootsector at the same time by fooling the operating system to think that the track resolved into the format it expected. Only a few games used that technique. Three of them were produced by Eclipse Software Design (Stone Age, Monster Business and Lethal Xcess). ST/Amiga Format magazine also used the technique for their coverdisks.

Amiga and PC dual-format games also existed, like the budget version of Rick Dangerous.

The game 3D Pool even contained a Tri-format disk, which contained the Amiga, Atari ST and PC versions of the game.

Most dual and tri-format disks were implemented using technology developed by Rob  Computing.

Recently, "dual format" has come to identify software which distributed on a single disk which includes both Windows and Macintosh versions of its installation program.

A list of a few of the Dual Format floppy disk titles:

Action Fighter (Amiga/PC dual-format disk)
Lethal Xcess - Wings of Death II (Amiga/Atari ST dual-format disks)
Monster Business (Amiga/Atari ST dual-format disk)
Populous: The Promised Lands (Amiga/Atari ST dual-format disk)
Rick Dangerous Kixx (Amiga/PC dual-format disk)
Rick Dangerous 2 Kixx (Amiga/PC dual-format disk)
Stone Age (Amiga/Atari ST dual-format disk)
Street Fighter (Amiga/PC dual-format disk)
StarGlider 2 (Amiga/Atari ST dual-format disk)
3D Pool (Amiga/Atari ST/PC tri-format disk)
Stunt Car Racer Kixx (Amiga/PC dual-format disk)
Bionic Commando Kixx (Amiga/PC dual-format disk)
Carrier Command Kixx (Amiga/PC dual-format disk)
Blasteroids Kixx (Amiga//PC dual-format disk)
E-Motion Kixx (Amiga//PC dual-format disk)
Indiana Jones and the Last Crusade Action Kixx (Amiga//PC dual-format disk)
Out Run Kixx (Amiga/PC dual-format disk)
World Class Leader Board Kixx (Amiga/PC dual-format disk)
International Soccer Challenge Kixx (Amiga/PC dual-format disk)
MicroProse Soccer Kixx (Amiga/PC dual-format disk)

See also

References

Amiga
Atari ST
IBM PC compatibles
Macintosh platform
Rotating disc computer storage media
Software distribution
Video game distribution