If formatting is handled by the application, you don't need to know what that application's disk operating system is—the application knows and will format disks the way it needs them to be formatted.

If formatting isn't handled by your application, you'll use the System Disk and you'll be asked whether you want the disk formatted for ProDOS or Pascal.

How do you know what operating system your application uses so you know how to answer the question? You can usually find out by looking at the label of the application program disk or by using the Catalog a Disk command on the System Disk. (See Figure 4-4.) If there is no operating system shown on the label, see if the application's operating system is mentioned in the application program's manual. (It will most likely be mentioned in the chapter that discusses how to save documents on disks.)

If you want to know why there are three disk operating systems for the Apple II, and more about them, read on.

In the beginning, there were only 5.25-inch disks and one system for saving information on them. The system was called DOS, an acronym for Disk Operating System. (Over the years, DOS was improved, and version numbers were tacked on to distinguish one version from the next. The last and best version was DOS 3.3.)

The first applications written for the Apple II were written either in assembly language (a programming language only slightly removed from the language of 0's and 1's that the Apple II speaks fluently) or in BASIC (a programming language that uses Englishlike words to tell the computer what to do). Both assembly-language programs and BASIC programs used the DOS 3.3 system for formatting disks and for saving and retrieving documents, so users didn't have to know what kind of program they were using.

Disk operating systems

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