Apple DOS 3.3
Source: - Apple DOS 3.3

Apple DOS 3.3

The Apple DOS 3.3 is a disk operating system developed by Apple in 1980 and preinstalled on the Apple IIe computer. DOS 3.3 has been publicly released on 25 August 1980 and was the first most commonly used DOS on personal computers. In 1983 DOS 3.3 has been replaced by ProDOS 8.

Apple DOS 3.3 was released in 1980 and improves various functions of release 3.2, while also allowing for large gains in available floppy disk storage; the newer P5A/P6A PROMs in the disk controller enabled the reading and writing of data at a higher density, so instead of 13 sectors (3.25 KiB), 16 sectors (4 KiB) of data can be stored per disk track, increasing the capacity from 113.75 KB to 140 KB per disk side – 16 KB of which is used by filesystem overhead and a copy of DOS, on a DOS 3.3-formatted disk, leaving 124 KB for user programs and data. DOS 3.3 is, however, not backward compatible; it cannot read or write DOS 3.2 disks. To address this problem, Apple Computer released a utility called “MUFFIN” to migrate Apple DOS 3.2 files and programs to version 3.3 disks. Apple never offered a utility to copy the other way. To migrate Apple DOS 3.3 files back to version 3.2 disks, someone wrote a “NIFFUM” utility. Release 3.3 also improves the ability to switch between Integer BASIC and Applesoft BASIC, if the computer has a language card (RAM expansion) or firmware card.

Today Apple DOS 3.3 is 40 years old!

Apple DOS 3.3 – General information


Introduced25 August 1980
System RequirementsApple IIe
DistributionFloppy disk

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