Rhapsody's OPENSTEP[a] based Yellow Box API frameworks were ported to Windows NT for creating cross-platform applications.

Apple made several attempts to develop modern replacements for Mac OS, which all failed, harming public confidence in the company, while Macintosh sales continued to decline.

In response, Apple CEO Gil Amelio decided to acquire or license an already-built operating system from another company.

Apple's executive team considered BeOS, NeXT's NeXTSTEP, Sun Microsystems' Solaris, and Windows NT, and eventually acquired NeXT in December 1996.

[3] Rhapsody was announced by Gil Amelio at the January 7, 1997 Macworld Expo SF,[5][6] and first demonstrated at the May 1997 Worldwide Developers Conference (WWDC).

[12] Additionally, Rhapsody itself could be installed on either PowerPC Macintoshes or Intel x86 PCs, enlarging developers' potential customer base.

[13] At Macworld SF 1997, Steve Jobs vaunted NeXTSTEP's maturity by pointing out that it had been adopted by many large organizations, including Wall Street banks and the CIA.

[20] Rhapsody uses Carnegie Mellon University's Mach 2.5 kernel, which was modified to add support for the Network File System, SCSI disks, and removable devices like CD-ROMs and Jaz drives.

[15] Mach had been created at CMU by Avie Tevanian, who was in charge of Rhapsody's development as Apple's senior vice president of software engineering, a role he previously held at NeXT.

[citation needed] Blue Box is a non-reentrant virtualization layer that allows Rhapsody to run classic Mac OS apps.

[21][15] Blue Box beta 1.0 only worked in full screen, requiring users to press ⌘ Cmd+↵ Enter to exit the environment, and it implements networking through Open Transport, instead of Rhapsody's BSD sockets.

[21] Rhapsody's Blue Box environment, available only on PowerPC due to paravirtualization, provides runtime compatibility with Mac OS 8 applications.

Apple modified its implementation of Open Firmware to allow users to dual boot Rhapsody and Mac OS by holding down ⇪ Caps Lock.

[26] BYTE magazine's Tom Thompson described DR1 as a "Jekyll-and-Hyde mixture" of an "amazingly Mac-like" user interface and hard-to-use NeXTSTEP components, some of which could only be configured properly through the command line, but said it "did not crash once" during his testing.

[8][12] Technology columnist Walt Mossberg observed that many third-party developers were already abandoning the Mac due to its shrinking market share, and that NeXTSTEP's lack of consumer applications, combined with the need to rewrite apps for Rhapsody, "[made] buying a Mac a relatively risky investment" compared to buying a Windows 95 or Windows NT computer.

However, the same month, Apple announced in an SEC filing that contrary to its previous earnings guidance, it would fail to return to profitability by the fourth quarter of fiscal year 1997 (ending in September), and that it expected Macintosh net sales to continue to decline.

[28] Shortly before the August 6, 1997 Macworld Expo Boston, Amelio tried to obtain a commitment from Microsoft to release Office for Rhapsody, but Bill Gates refused.

[28] In February 1998, Macworld columnist David Pogue wrote: The intriguing thing about Apple's upcoming Rhapsody OS is that it'll be available for Mac and Intel computers.

[31][needs context] In mid-1997, after Amelio was ousted as Apple's CEO and Jobs informally replaced him, the company grew quieter on Rhapsody, leading to speculation over its fate.

[32][33][24] At WWDC 1998 held in May, Apple stated that "not a single" major third-party developer had committed to rewriting their apps for Rhapsody.

[citation needed] Apple also announced that Adobe, Microsoft and Macromedia were on board with the new strategy, and had committed to releasing their applications for Mac OS X.

[35] As part of the landmark Microsoft antitrust trial, Avie Tevanian argued that Rhapsody's failure was partly caused by Windows's dominance, which made new operating system platforms inherently uncompetitive; however, The Register's John Lettice argued that "those [Yellow Box] APIs Apple couldn't get developers to support [...] are of course APIs that NeXT couldn't get developers to support".

Many NeXTSTEP innovations were foundational to Mac OS X, including the Cocoa framework, Interface Builder (which became part of Xcode), and the Objective-C programming language.