Released on the 30th anniversary of the introduction of the Apple II GS, ProDOS 2.4 brings the improved operating system to even older Apple II systems, including the original Apple ][ and ][+. It updates ProDOS, the last version of which, 2.0.3, was released in 1993. Further, the release includes a number of new features, wrap-in programs, and bug fixes. Jason Scott, a computer historian, has set up a Web-based emulator on the Internet Archive where you can test-drive ProDOS 2.4 . The ProDOS 2.4 “floppy” includes an assortment of utilities, including a MiniBas tiny BASIC interpreter, the “Unshrink” expander for uncompressing files archived with Shrinkit (helpful for using Apple II archives distributed over the Internet), and disk imaging programs to move files from physical floppies to USB and other disk storage, file utilities. All of the above can fit into a single 140k 5.25-inch disk image. In addition, the release also includes Bitsy Bye, a menu-driven program launcher that allows for navigation through files on multiple floppy (or hacked USB) drives. Bitsy Bye is an example of highly efficient code: it runs in less than 1 kilobyte of RAM. There’s also a boot utility that is under 400 bytes—taking up a single block of storage on a disk. The complete list of improvements, additions and fixes is on the Internet Archive page. You can download the release, or boot it in an emulator on the webpage. Source: Arstechnica
