A Brief History of Apple DOS
When Apple released the original Apple and Apple II computers, they didn't come with a disk drive. Like most early microcomputers, software was loaded using cassette tapes, which were the simplest method at the time.
That changed in June 1978 when Apple introduced the Disk II for the Apple II, allowing users to store 113.75K per side on a 5.25-inch floppy disk. In 1979, the release of DOS 3.3 boosted that capacity to 140K per side. This upgrade is worth noting, as it marked a key improvement over earlier DOS versions, which supported only 13 tracks per side (compared to DOS 3.3's 16). For this reason, DOS 3.3 and later versions are the primary focus when working with disk images today.
DOS 3.3, like earlier versions, was tailored to work with the Apple II's built-in BASIC language, offering commands for loading, saving, and running programs. Alongside its increased capacity, DOS 3.3 also introduced various bug fixes with each minor release.
One limitation to keep in mind is that DOS 3.3 only supports 5.25-inch floppy disks; it doesn't work with hard drives or 3.5-inch media. However, any game written in BASIC or assembly language for the Apple II, distributed on 5.25-inch floppy disks or compatible disk images, will work perfectly within this setup.