History: The Origins of Mac OS X

The original macOS was called NeXTSTEP OS

Joaquín Menchaca (智裕)
7 min readApr 21, 2024


I am surprised that most do not know this story that the operating system that we use today on Macbooks called Mac OS X was once called NeXTSTEP operating system .

After Steve Jobs left Apple Computer, Inc in 1985, he founded a new company named NeXT, Inc. that made a new powerful workstation computer and a revolutionary new operating system called NeXTSTEP OS (operating system).

Apple made NeXTSTEP OS the new direction of the company, and in 2001 released Mac OS X 1.0. This version of this operating system was used on other products that included Apple Watch, Apple TV, and the iPhone.

The new operating system features a redesigned interface that closely resembles Apple’s previous operating system, aiming to make the transition smoother for users. The intention likely was that, over time, customers may not even realize that the underlying operating system has changed.

Apple’s Previous System

Before NeXTSTEP and later Mac OS X, the original operating system used by Apple came in two parts: one part that was installed on the hardware called Toolbox, and another part installed on disk that was simply called System.

System 6.0.8

In 1996, this operating system called System underwent a rebranding, emerging as Mac OS. Renowned for its advanced graphics capabilities, intuitive interface, and a robust suite of applications spanning word processing, desktop publishing, illustration, image editing, video production, music sequencing, and more, Mac OS became a cornerstone of various industries. Its impact was profound, reshaping realms such as law, journalism, photography, video production, and healthcare. Apple even dedicated a specialized group, known as MIQ (Multimedia Integration Quality), to ensure seamless integration with these diverse sectors.

Mac OS 9 (classic Mac OS)

The newly rebranded NeXTSTEP, now known as Mac OS X, initially supported fewer than a hundred applications. This was a stark contrast to the classic Mac OS, which supported thousands of applications, including highly popular ones such as Word (1983), PageMaker (1985), Canvas (1987), Excel (1987), Illustrator (1987), and Photoshop (1990), among others.

Despite the last operating system, Mac OS 9.2.2 in 2001, people would not stop using and developing for classic Mac OS. Steve Jobs would give his famous (or infamous) coffin presentation in 2006 to show that the classic Mac OS was dead.

A Tale of Three OSes

In 1996, Apple lacked a modern operating system capable of scaling effectively or competing in the market. The system in use at the time, recently rebranded as Mac OS was notoriously difficult and costly to maintain. I remember a period when the startup process involved applying over 4,000 patches, with some patches designed to correct or prevent issues caused by other patches — a highly chaotic situation.

Patches patching patches to stop patches from patching patches to patch patches

Additionally, the operating system did not support true multitasking. Applications did not run simultaneously but were instead swapped in and out, causing other applications to pause in the background. If one application failed, it could crash the entire system, leading to data loss and requiring a system restart. Without frequent saves, users risked losing their work.

Apple was in a critical situation and urgently needed a new operating system to regain its competitive edge. There were at least three potential operating systems that could have revitalized Apple’s technology platform.


Apple was internally developing a new operating system known as Project Maxwell, publicly referred to as Copland, which operated on the NuKernel, a microkernel architecture inspired by Mach 3.0 .

Ultimately, Maxwell (Copland) proved to be a failure. It lacked compatibility with existing applications and initially featured only a command-line interface, missing a graphical user interface API necessary to support multitasking applications.

With no viable solutions from its current leadership to address these shortcomings, Apple began exploring options to acquire an operating system.

📔 Personal Note: In another lifetime, I developed test tools to test driver compatibility for the never released operating system at Apple. Before that I tested the classic Mac OS on Motorola 68K and PowerPC architectures.


Apple was contemplating the acquisition of BeOS from Be, Inc., a company established by former Apple executives Jean-Louis Gassée, the former COO, and Steve Sakoman, the director of hardware engineering, who played a pivotal role in developing Apple’s first mobile computer, the Newton.

Initially, Be, Inc. marketed a piece of hardware known as the BeBox in 1995, which ran BeOS, an operating system, and like Apple’s NuKernel, was also based on a microkernel architecture.


“BeOS was an insanely fast and efficient operating system for its time. It could boot in less than 10 seconds, supported dual processors, and … one of the company’s favorites stunts was using it to run multiple videos at once. That might not sound like much today, but it was enough to wow ‘90s computer users who were used to waiting minutes for Windows to boot and were lucky if they could play even a single video at a time.” — Klint Finley, Wired


In 1997, as Apple was finalizing its acquisition of NeXT, Inc. for $427 million, an amount equivalent to $816 million in today’s dollars. This purchase provided Apple with a new operating system, NeXTSTEP.

The decisive factor for Apple’s CEO Gil Amelio in choosing NeXTSTEP over BeOS was that NeXTSTEP was already ran on Intel processors, whereas BeOS was initially designed for PowerPC, the same processor used by Macintosh computers at the time.

📓 Side note: BeOS was subsequently ported to Intel processors just a few months after Apple’s acquisition of NeXT.

Apple made Rhapsody available as a developer release in May 1998.

Rhapsody Developer Release

The final product was Mac OS X Server 1.0, released in 1999. Built upon NeXTSTEP, which utilizes a monolithic Mach kernel with a BSD Unix subsystem, this system could support many popular Unix services such as Postfix, Apache, OpenLDAP, and Samba, in addition to Apple File Services.

In 2001, Apple introduced its first client operating system Mac OS X 1.0 (Cheetah), designed for Macintoshes running PowerPC processors.


The journey of Apple’s operating systems — from the classic Mac OS to NeXTSTEP and Mac OS X — represents a significant evolution in software technology that has had a profound impact on Apple’s product line and industry standing. When Steve Jobs returned to Apple after his tenure at NeXT, Inc., he brought with him more than just a new operating system; he brought a vision that would fundamentally change Apple.

NeXTSTEP (Mac OS X), laid the groundwork for future innovations, supporting later versions of macOS and other products like the iPhone, Apple Watch, and Apple TV.

This transition was not merely a technical upgrade but a strategic move that addressed the chronic issues of the previous system which was plagued by inefficiencies and limited capabilities. Despite the initial scarcity of applications compatible with Mac OS X compared to the thousands available for its predecessor, the operating system’s superior architecture and robustness gradually won over developers and users alike.

Steve Jobs’s famous 2006 “coffin” presentation, declaring the end of classic Mac OS, underscored the completion of a significant chapter in Apple’s history. The new era of Mac OS X, starting with its first release in 1999 and continuing through its evolution, has proven to be a keystone in Apple’s modern success, demonstrating the power of embracing change and innovation to overcome past limitations and set new industry standards.


Here are articles I’ve encountered that cover various Mac operating systems, including classic Mac OS, Mac OS X, and the original NeXTSTEP OS.



Classic Mac OS

Mac OS X (now macOS) and iOS