"Rhapsody" DR1 and DR2 were the developper releases (beta) of what would soon become Mac OS X Server 1.0 and then Mac OS X 10.0.  Rhapsody is a software product, named NeXTSTEP from 1989 to 1997, that Steve Jobs developped and brought...

This was the may 1990 release of macintosh system software 7.0a9 (which most likely means 7.0 alpha 9). Along with an early/development version of the operating system, the disc included lots of developer tools and other special...

Those are trimmed down versions of Mac OS 7.0 betas. See also: the full 7.0a9 CD image containing developer tools See also: the full 7.0b4 CD image  

    The Mac OS X Public Beta (internally codenamed "Kodiak") was an early beta version of Apple Computer's Mac OS X operating system Cheetah. It was released to the public on September 13, 2000 for US$29.95. It...

Copland OS was supposed to be the turning point of classic Mac OS.  Starting from 1994, it was supposed to introduce true multitasking, protected memory.  Copland could have been the foundation of Mac OS X altough it was commonly being...

MacOS 8.7 is supposedly a cancelled MacOS 8.x update, that became MacOS 9 for PPC. As shown by Action Retro, it can be run on a PowerBook 540c that has a PPC upgrade inside, however, at least for him, the wallpaper becomes the...

This is the Beta Release of Macintosh System Software 7.1b7. Along with the beta operating system, the disc includes lots of developer tools and other goodies.

Mac OS Copland D12 MacCrash Edition, Repack for 2020 :) "Combined Copland Ta2c5, D7e1, D9OPT, D11E4" home built hard disk image.  

These are the 5 pre-releases of Mac OS 9.2.x that I found recently. You need to use QEMU or real supported PowerPC Macs (such as the blue and white Power Mac G3) or this will not work. It is also recommended to boot into Mac OS 9.1 along with...

See also: The full 7.1b7 CD  

Harmony is the next reference release of the Mac OS, slated for release in January 1997. It will support all Mac OS computers which are 32-bit clean and have a 68030 processor or "better" as originally shipped. Harmony does not support...

This is a pre-release of mac os 7.0 known as 7.0.B4 "Superbeta"