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.