computer science

Mac operating systems

Mac operating systems is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Mac operating systems rather than just read about it. In short: Mac operating systems were developed by Apple in a succession of two major series. In 1984, Apple debuted the operating system that is now known as the classic Mac OS with its release of the original Macintosh System Software.

Key takeaways

Mac operating systems belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Mac operating systems to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Mac operating systems from memory before moving on to harder problems.

Reference excerpt

Mac operating systems were developed by Apple in a succession of two major series. In 1984, Apple debuted the operating system that is now known as the classic Mac OS with its release of the original Macintosh System Software. The system, rebranded Mac OS in 1997, was pre-installed on every Macintosh until 2002 and offered on Macintosh clones shortly in the 1990s. It was noted for its ease of use, and also criticized for its lack of modern technologies compared to its competitors. The current Mac operating system is macOS, originally named Mac OS X until 2012 and then OS X until 2016. It was developed between 1997 and 2001 after Apple's purchase of NeXT. It brought an entirely new architecture based on NeXTSTEP, a Unix system, that eliminated many of the technical challenges that the classic Mac OS faced, such as problems with memory management. The current macOS is pre-installed with every Mac and receives a major update annually. It is the basis of Apple's current system software for its other devices – iOS, iPadOS, watchOS, and tvOS. Prior to the introduction of Mac OS X, Apple experimented with several other concepts, releasing different products designed to bring the Macintosh interface or applications to Unix-like systems or vice versa, A/UX, MAE, and MkLinux. Apple's effort to expand upon and develop a replacement for its classic Mac OS in the 1990s led to a few cancelled projects, code named Star Trek, Taligent, and Copland. Although the classic Mac OS and macOS (Mac OS X) have different architectures, they share a common set of GUI principles, including a menu bar across the top of the screen; the Finder shell, featuring a desktop metaphor that represents files and applications using icons and relates concepts like directories and file deletion to real-world objects like folders and a trash can; and overlapping windows for multitasking. Before the arrival of the Macintosh in 1984, Apple's history of operating systems began with its Apple II computers in 1977, which run Apple DOS, ProDOS, and GS/OS; the Apple III in 1980 runs Apple SOS; and the Lisa in 1983 which runs Lisa OS and later MacWorks XL, a Macintosh emulator. Apple developed the Newton OS for its Newton personal digital assistant from 1993 to 1997. Apple launched several new operating systems based on the core of macOS: iOS in 2007 for its iPhone, iPad, and iPod Touch mobile devices, and in 2017 for its HomePod smart speakers; watchOS in 2015 for the Apple Watch; tvOS in 2015 for the Apple TV set-top box; and visionOS in 2024 for the Apple Vision Pro mixed reality headset.

Classic Mac OS

The classic Mac OS is the original Macintosh operating system introduced in 1984 alongside the first Macintosh and remained in primary use on Macs until Mac OS X in 2001. Apple released the original Macintosh on January 24, 1984; its early system software is partially based on Lisa OS, and inspired by the Alto computer, which former Apple CEO Steve Jobs previewed at Xerox PARC. It was originally named "System Software", or simply "System"; Apple rebranded it as "Mac OS" in 1996 due in part to its Macintosh clone program that ended one year later. Classic Mac OS is characterized by its monolithic design. Initial versions of the System Software run one application at a time. System 5 introduced cooperative multitasking. System 7 supports 32-bit memory addressing and virtual memory, allowing larger programs. Later updates to the System 7 enable the transition to the PowerPC architecture. The system was considered user-friendly, but its architectural limitations were critiqued, such as limited memory management, lack of protected memory and access controls, and susceptibility to conflicts among extensions.

Releases

Nine major versions of the classic Mac OS were released. The name "Classic" that now signifies the system as a whole is a reference to a compatibility layer that helped ease the transition to Mac OS X.

Macintosh System Software – "System 1", released in 1984 System Software 2, 3, and 4 – released between 1985 and 1987 System Software 5 – released in 1987 System Software 6 – released in 1988 System 7 / Mac OS 7.6 – released in 1991 Mac OS 8 – released in 1997 Mac OS 9 – final major version, released in 1999

Mac OS X, OS X, and macOS

The system was launched as Mac OS X, renamed OS X from 2012—2016, and then renamed macOS as the current Mac operating system that officially succeeded the classic Mac OS in 2001. The system was originally marketed as simply "version 10" of Mac OS, but it has a history that is largely independent of the classic Mac OS. It is a Unix-based operating system built on NeXTSTEP and other NeXT technology from the late 1980s until early 1997, when Apple purchased the company and its CEO Steve Jobs returned to Apple. Precursors to Mac OS X include OPENSTEP, Apple's Rhapsody project, and the Mac OS X Public Beta. macOS is based on Apple's open source Darwin operating system, which is based on the XNU kernel and BSD. macOS is the basis for some of Apple's other operating systems, including iPhone OS/iOS, iPadOS, watchOS, tvOS, and visionOS.

Releases

Desktop The first version of the system was released on March 24, 2001, supporting the Aqua user interface. Since then, several more versions adding newer features and technologies have been released. Since 2011, new releases have been offered annually.

… excerpt ends here. Continue reading the full article.

Illustrations

The "X" logo for Mac OS X versions 10.0 "Cheetah" and 10.1 "Puma", released in 2001

Worked examples

Example 1 — a first encounter with Mac operating systems

Start with the simplest possible case. Write down what Mac operating systems claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Mac operating systems before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Mac operating systems ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Mac operating systems

In research: Mac operating systems appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Mac operating systems in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Mac operating systems is common in secondary-school and first-year university syllabi. It links to neighbouring topics Apple Inc. software, History of software, Lists of operating systems, so understanding it makes those chapters shorter.
In everyday life: Look for Mac operating systems outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Mac operating systems in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Mac operating systems means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Mac operating systems out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Mac operating systems in simple terms?

Why does Mac operating systems matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Mac operating systems?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Mac operating systems.