Apple DOS 3.1 was publicly released in June 1978, slightly less than one year after the Apple II was introduced, becoming the first disk-based operating system for any Apple computer. A bug-fix release came later, addressing a problem with its MASTER CREATE utility, which was used to create Apple DOS master disks: The built-in INIT command created disks that could be booted only on machines with at least the same amount of memory as the one that had created them. MASTER CREATE included a self-relocating version of DOS that would boot on Apples with any memory configuration.