<P> With the purchase of NeXT in late 1996, Apple developed a new operating system strategy based largely on the existing OpenStep platform . The new Rhapsody was relatively simple; it retained most of OpenStep's existing object libraries under the name "Yellow Box", ported OpenStep's existing GUI and made it look more Mac - like, ported several major APIs from the Mac OS to Rhapsody's underlying Unix - like system (notably QuickTime and AppleSearch), and added an emulator known as the "Blue Box" that ran existing Mac OS software . </P> <P> When this plan was unveiled at the Worldwide Developers Conference in 1997 there was some push - back from existing Mac OS developers, who were upset that their code bases would effectively be locked into an emulator that was unlikely to ever be updated . They took to calling the Blue Box the "penalty box". Larger developers like Microsoft and Adobe balked outright, and refused to consider porting to OpenStep, which was so different from the existing Mac OS that there was little or no compatibility . </P> <P> Apple took these concerns to heart . When Steve Jobs announced this change in direction at the 1998 WWDC, he stated that "what developers really wanted was a modern version of the Mac OS, and Apple (was) going to deliver it". The statement was met with thunderous applause . The original Rhapsody concept was eventually released in 1999 as Mac OS X Server 1.0, the only release of its type . </P> <P> In order to offer a real and well supported upgrade path for existing Mac OS code bases, Apple introduced the Carbon system . Carbon consists of many libraries and functions that offer a Mac - like API, but running on top of the underlying Unix - like OS, rather than a copy of the Mac OS running in emulation . The Carbon libraries are extensively cleaned up, modernized and better "protected". While the Mac OS was filled with APIs that shared memory to pass data, under Carbon all such access was re-implemented using accessor subroutines on opaque data types . This allowed Carbon to support true multitasking and memory protection, features Mac developers had been requesting for a decade . Other changes from the pre-existing API removed features which were conceptually incompatible with Mac OS X, or simply obsolete . For example, applications could no longer install interrupt handlers or device drivers . </P>

When did apple introduce its first computer with an api interface