TITLE
ProDOS: Product Overview 

Article ID: 180
Created: 9/21/84
Modified: 7/20/98
 

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TOPIC 
ProDOS is Apple's new disk operating system for the Apple IIe and II+. It is now included with Apple's Disk II drives with controller and the DuoDisk.



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DISCUSSION 

Apple designed ProDOS as a transition from DOS 3.3 and for the greater sophistication and enhanced capabilities demanded by more professional applications. ProDOS provides compatibility between the Apple III and the Apple II line of computers, since ProDOS and SOS share similar file naming conventions and file formats.

ProDOS requires a 64K Apple II+ or IIe, with Applesoft in ROM. Integer BASIC is not supported. Listed below are some of the features of ProDOS.

--Hierarchical file system similar to SOS.

--Up to 51 files in a volume directory; the number of files in subdirectories is limited only by the space on the disk.

--20 different file types; 10 are user-defineable.

--Up to 8 files may be open at one time.

--A defined, usable machine language interface.

--Interrupts up to 4 levels are supported and processed sequentially.

--Compatibility between files created on an Apple III.

--Fast transfer speed to and from disk; about 8K per second from Disk II.

--All disk devices supported by Apple will work automatically.

--Direct block access.

--Enhanced BASIC command structure.

--Easier Assembly Language program development and maintenance.

--Up to 32 megabytes per volume, 16 megabytes per file.

--Multiple logical volumes per physical volume.

--Pseudo disk emulator using the Apple Extended Text Card, enabling fast file access and graphics screen switching.