Rosetta (software)

Operating system component

For other software products or projects named "Rosetta", see Rosetta Stone (software) and Rosetta (disambiguation).

Rosetta

Rosetta 2 installation prompt

Developer(s)| Apple Inc.
Operating system| Mac OS X 10.4.4–10.6.8 (Intel host, emulating PowerPC)
macOS 11.0–present (ARM host, emulating Intel)
ARM Linux guest emulating Intel[1]
Type| Binary translation, emulation
Website| https://support.apple.com/en-us/102527

Rosetta is a dynamic binary translator developed by Apple Inc. for macOS, an application compatibility layer between different instruction set architectures. It enables a transition to newer hardware, by automatically translating software. The name is a reference to the Rosetta Stone, the artifact which enabled translation of Egyptian hieroglyphs.[2]

The first version of Rosetta was introduced in 2006 in Mac OS X Tiger as part of the Mac transition from PowerPC processors to Intel processors, allowing PowerPC applications to run on Intel-based Macs. Support for Rosetta was dropped with Mac OS X Lion (10.7) in 2011.

Rosetta 2 was introduced in 2020 as a component of macOS Big Sur, and as part of the Mac transition from Intel processors to Apple silicon, allowing Intel applications to run on Apple silicon-based Macs.[3] Most Rosetta 2 features will be removed from macOS with version 28 in 2027.

## Background

[edit]

Macintosh has used CPUs with several different instruction set architectures (ISA): the Motorola 68000 series, PowerPC, Intel x86, and ARM64 in Apple silicon. Each ISA is incompatible, necessitating a transition plan based on a software layer to emulate the previous ISA on the succeeding one.

With the launch of Power Macintosh, the Mac 68K emulator is part of System 7.1.2 and later. This emulator uses PowerPC features and is embedded at the lowest levels of the operating system, integrated with the Mac OS nanokernel. This means that the nanokernel is able to intercept PowerPC interrupts, translate them to 68k interrupts (then doing a mixed mode switch, if necessary), and then execute 68k code to handle the interrupts. This allows 68k and PowerPC code to be interspersed within the same fat binary.

## Rosetta

[edit]

Mac transition to
Intel processors

* PowerPC
* Architecture
* Universal binary
* Boot Camp
* Rosetta
* Developer Transition Kit

* v
* t
* e

Apple launched Rosetta in 2006 upon the Mac transition to Intel processors from PowerPC. It is in Mac OS X Tiger 10.4.4 "Tiger", the version that launched the x86-based Macs, and allows many unmodified PowerPC applications to automatically run on Intel-based Mac computers. Rosetta is based on QuickTransit technology.[4] It has no graphical user interface, and launches transparently, which led Apple to describe Rosetta as "the most amazing software you'll never see".[5] Rosetta is optionally installable in Mac OS X 10.6 "Snow Leopard".[6] Rosetta is neither included nor supported in Mac OS X 10.7 "Lion" (released in 2011) or later.[6]

Because of the greater architectural differences between Intel and PowerPC processors, Rosetta operates at a higher level than the 68000 emulator does, as a user-level program that can only intercept and emulate user-level code. It translates G3, G4, and AltiVec instructions, but not G5. Although most commercial software for PowerPC-based Macs was compatible with these requirements and G4 systems were still widely used, developers must update any applications that rely on G5-specific instructions to work on Rosetta. Apple advised that applications with heavy user interaction but low computational needs (such as word processors) would be best suited to use with Rosetta, and applications with high computational needs (such as games, AutoCAD, or Photoshop) would not.[7]

## Rosetta 2

[edit]

Mac transition to
Apple silicon

* Apple silicon (M series)
* ARM architecture family
* Universal 2 binary
* Rosetta 2
* Developer Transition Kit

* v
* t
* e

In 2020, Apple announced Rosetta 2 would be bundled with macOS Big Sur, to aid in the Mac transition to Apple silicon. The software permits many applications compiled exclusively for execution on x86-64-based processors to be translated for execution on Apple silicon.[3][8]

In addition to the just-in-time (JIT) translation support, Rosetta 2 offers ahead-of-time compilation (AOT), with the x86-64 code fully translated, just once, when an application without a universal binary is installed on an Apple silicon Mac.[9]

Rosetta 2's performance has been praised greatly.[10][11] In some benchmarks, x86-64-only programs performed better under Rosetta 2 on M1 than native x86-64. One of the key reasons why Rosetta 2 provides such a high level of translation efficiency is the support of x86-64 memory ordering in the M1 SoC.[12] The SOC also has dedicated instructions for computing x86 flags.[13]

Since macOS Ventura, Linux guest operating system virtual machines can install Rosetta 2 as a guest runtime binary to run x86-64 Linux apps.[14][15]

At WWDC 2025, Apple stated that most Rosetta 2 features will be removed from macOS with version 28 in 2027, with support limited to unmaintained games.[16]

## See also

[edit]

* Fat binary § Apple's fat binary – combined 68k/PPC applications that run natively on both processors
* Mac 68k emulator – a similar feature in classic Mac OS that translates 680x0 instructions to PowerPC instructions
* Universal binary – combined PPC/Intel applications that run natively on both processors
* Universal 2 binary – combined Intel/ARM applications that run natively on both processors

## References

[edit]

1. ^ "Running Intel Binaries in Linux VMs with Rosetta". Apple Inc. Retrieved August 7, 2022.
2. ^ Norr, Henry (January 27, 2006). "Core Duo iMacs debut speedy new chips". Macworld.
3. ^ a b Warren, Tom (June 22, 2020). "Apple is switching Macs to its own processors starting later this year". The Verge. Retrieved June 22, 2020.
4. ^ "The brains behind Apple's Rosetta: Transitive". CNET. June 8, 2005. Retrieved January 9, 2023.
5. ^ "Rosetta". Apple. Archived from the original on January 13, 2006. Retrieved September 5, 2011.
6. ^ a b AppleInsider Staff (February 26, 2011). "Mac OS X Lion drops Front Row, Java runtime, Rosetta". AppleInsider. AppleInsider, Inc. Archived from the original on April 29, 2014. Retrieved February 27, 2011.
7. ^ "Rosetta" (PDF). Universal Binary Programming Guidelines, Second Edition. Apple. Archived from the original (PDF) on August 3, 2012. Retrieved September 5, 2011.
8. ^ Mayo, Benjamin (June 22, 2020). "Apple announces Mac architecture transition from Intel to its own ARM chips, offers emulation path". 9to5Mac. Retrieved June 23, 2020.
9. ^ WWDC2020 Keynote. Apple Inc. June 22, 2020. Event occurs at 1h39m37s. "It translates the apps when you install them, so they can launch immediately and can be instantly responsive. Rosetta 2 can also translate code on the fly when needed."
10. ^ Evans, Jonny (November 19, 2020). "Everything you need to know about Rosetta 2 on Apple Silicon Macs". Computerworld. Retrieved December 8, 2020.
11. ^ "Yeah, Apple's M1 MacBook Pro is powerful, but it's the battery life that will blow you away". TechCrunch. November 17, 2020. Retrieved December 8, 2020.
12. ^ Wrenger, Lars; Töllner, Dominik; Lohmann, Daniel (April 1, 2024). "Analyzing the memory ordering models of the Apple M1". Journal of Systems Architecture. 149: 103102. doi:10.1016/j.sysarc.2024.103102. ISSN 1383-7621.
13. ^ Dougall, J (November 9, 2022). "Why is Rosetta 2 fast?". Retrieved August 15, 2023. "ARM flag-manipulation extensions... Apple's secret extension..."
14. ^ Proven, Liam (June 9, 2022). "Apple offers improved Linux support in macOS 13". The Register. Retrieved January 6, 2023.
15. ^ Cunningham, Andrew (June 7, 2022). "Apple will allow Linux VMs to run Intel apps with Rosetta in macOS Ventura". Ars Technica. Retrieved January 6, 2023.
16. ^ Cunningham, Andrew (June 9, 2025). "Apple details the end of Intel Mac support and a phaseout for Rosetta 2". Ars Technica. Retrieved June 10, 2025.

## External links

[edit]

* Apple Rosetta Web site at the Wayback Machine (archived January 7, 2011)
* Transitive Corporation web site at the Wayback Machine (archived September 14, 2008)
* Rosetta compatibility index at the Wayback Machine (archived February 8, 2006)
* Does it ARM? – Rosetta 2 compatibility index

* v
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