OFS (Old File System) was the original file system introduced with AmigaDOS 1.0, designed primarily for floppy disk storage. It utilized a linked-list structure where each data block contained a pointer to the next block, causing significant seek overhead and poor performance on hard drives. Due to these inefficiencies, it was largely superseded by the Fast File System (FFS) in AmigaOS 1.3, though OFS remained supported for backward compatibility with floppy disks.