Latest release of ProDOS is 2.4.3

ProDOS 2.5 alpha 8 pre-release is available

About ProDOS-8

Professional Disk Operating System

  • ProDOS stands for: Professional Disk Operating System.

  • ProDOS was released for the Apple II series of computers in January 1983.

  • ProDOS was distributed by Apple until 1993.

  • ProDOS is the last official operating system usable by all 8-bit Apple II series computers.


ProDOS …. 8 ?

  • The Apple II was an 8-bit computer.

  • The Apple IIgs was an 16-bit computer, which had backwards compatibility with the 8-bit Apple II’s.

  • When the Apple IIgs was released, it came with a 16-bit version of ProDOS, officialy called ProDOS-16. ProDOS-16 was officially replaced by GS/OS once it was ready.

  • When the Apple IIgs was released, ProDOS for 8-bit computers was version 1.2, and renamed to ProDOS-8.


Differences with DOS

  • The original Apple II DOS only has built-in support for 5.25” floppy disks. However, ProDOS includes support for 3.5” disks.

  • DOS has no subdirectory support. ProDOS has support for hierarchical subdirectories.

  • The maximum volume size supported by DOS is 400k. ProDOS supports volumes up to 32mb.

  • ProDOS includes RAM disk support on machines with 128kB or more RAM.

  • ProDOS supports the RTC (Real Time Clock), however only the Apple IIgs has a RTC built-in.


Life after Death

  • The last official release of ProDOS was 2.0.3 in 1993.

  • On September 15th, 2016 John Brooks released the 2.4 version of ProDOS on the 30th anniversary of the introduction of the Apple IIgs.

  • Originally ProDOS did not include support for the original Apple ][ or the ][+, however This release added support for the Apple ][ and ][+ models, making it the first release of ProDOS that would run on ALL Apple II’s.

  • The release includes Bitsy Bye, a menu-driven program launcher that allows for navigation through files on multiple floppy drives.


John Brooks

  • The developer of ProDOS after 2.0.3.

  • Apple ][ developer since 1979.

  • Professional game developer since 1987.

  • In 1995, cofounded Blue Shift, Inc. in San Jose, CA., a company which develops video games, embedded systems, and provides engineering consulting services.