Apple DOS

Apple DOS

Apple DOS was the family of disk operating systems for the Apple II series of microcomputers from Apple Computer. It was the first operating system for the Apple II series, and it was the primary operating system for these computers until it was replaced by ProDOS in 1983.

History

Apple DOS was developed by Sheppard Associates under contract from Apple Computer. The first version, Apple DOS 3.1, was released in June 1978. The development of Apple DOS was initiated because Apple needed a disk operating system to manage the new Disk II floppy disk drive, which was designed by Steve Wozniak.

Versions

• Apple DOS 3.1: Released in June 1978, it was the first version of Apple DOS. It supported the Disk II drive and allowed users to store and retrieve data from floppy disks.
• Apple DOS 3.2: Released in 1979, this version included bug fixes and improvements over DOS 3.1.
• Apple DOS 3.3: Released in 1980, it was the most popular version of Apple DOS. It included enhancements such as improved disk handling and support for larger disk sizes.

Features

Apple DOS provided a command-line interface for managing files and programs on floppy disks. It included commands for:

• Listing files on a disk
• Copying files
• Deleting files
• Renaming files
• Running programs

The operating system was loaded from a floppy disk at startup, and it remained in memory while the computer was running.

Technical Details

Apple DOS was written in 6502 assembly language, which was the native language of the MOS Technology 6502 microprocessor used in the Apple II. The operating system was designed to be compact and efficient, fitting into the limited memory available on the Apple II.

Disk Format

Apple DOS used a proprietary disk format that was specific to the Disk II drive. The format included:

• 35 tracks per disk
• 13 sectors per track
• 256 bytes per sector

This format allowed for a total storage capacity of approximately 113.75 KB per disk.

Legacy

Apple DOS was a significant milestone in the history of personal computing. It provided Apple II users with the ability to store and manage data on floppy disks, which was a major advancement over cassette tape storage. Apple DOS laid the groundwork for future operating systems on the Apple II, including ProDOS and GS/OS.

See Also

• Apple II series
• ProDOS
• Disk II
• Steve Wozniak

References

• "Apple DOS Manual," Apple Computer, Inc.
• "The Apple II Circuit Description," Winston D. Gayler