Why Older Software Hasn’t Been Rewritten for ARM — And How It Shapes Future Device Adoption

Introduction

The computing industry is undergoing a profound architectural shift. For decades, x86 processors from Intel and AMD dominated desktops, laptops, and servers. Meanwhile, ARM processors quietly rose to dominance in the mobile world, powering billions of smartphones and embedded devices. Today, ARM is moving aggressively into new territories: laptops, desktops, and cloud servers. Apple’s transition to Apple Silicon, Microsoft’s Windows-on-ARM initiative, and cloud providers like AWS (with its Graviton processors) are reshaping the landscape.

Yet, despite ARM’s clear advantages — energy efficiency, strong performance-per-watt, and scalable designs — one major obstacle remains: software compatibility. A huge portion of the world’s software ecosystem was built for x86. Older applications, libraries, and drivers often remain tightly bound to Intel/AMD architectures, making rewriting them for ARM expensive, time-consuming, or in some cases nearly impossible.

This article explores why older software hasn’t been rewritten for ARM, and the impact this has on adoption of ARM-based devices. We’ll look at the historical evolution of x86 dominance, the rise of ARM, the technical and business challenges of rewriting, the role of emulation, and the strategies Apple, Microsoft, and cloud vendors are using to overcome this barrier. Finally, we’ll consider the long-term future: will ARM truly displace x86, or will legacy inertia slow down its progress?

1. The Historical Context: x86 Dominance

1.1 The x86 Legacy

Intel’s x86 architecture, born with the Intel 8086 in 1978, became the foundation of the IBM PC and all its descendants. Over four decades, x86 became deeply entrenched:

Enterprise applications like SAP, Oracle databases, and Microsoft Exchange were designed for x86 servers.
Consumer applications like Microsoft Office, Adobe Photoshop, and countless PC games were optimized for Windows on Intel/AMD hardware.
Toolchains and compilers were heavily tuned to x86 instruction sets, providing predictable performance improvements.

By the 1990s and 2000s, x86 was synonymous with computing outside of mobile and embedded systems.

1.2 ARM’s Rise in Parallel

ARM, on the other hand, originated in the late 1980s with a focus on low-power, RISC-based designs. ARM processors found their niche in embedded devices and later became the powerhouse behind smartphones.

Mobile dominance: Nearly every smartphone today runs on ARM.
Battery efficiency: ARM’s simpler instruction set allows excellent performance per watt.
Customization: ARM licenses its architecture, letting companies like Apple, Qualcomm, and Samsung design tailored chips.

While ARM took over mobile, x86 retained a stranglehold on PCs, laptops, and servers because of legacy software compatibility.

2. Why Older Software Hasn’t Been Rewritten for ARM

Despite ARM’s growing importance, vast amounts of software remain tied to x86. The reasons are multi-layered:

2.1 Immense Codebases and Cost of Rewriting

Large enterprise and desktop applications often consist of millions of lines of code written in C, C++, or even assembly. Rewriting or porting these to ARM requires not just recompilation but deep testing, bug fixing, and re-optimization. For many companies, the ROI doesn’t justify the engineering cost, especially if the existing x86 user base remains strong.

2.2 Legacy Dependencies and Proprietary Components

Many applications depend on third-party libraries, middleware, or drivers that exist only for x86. Even if the main program can be recompiled for ARM, these dependencies become blockers.

Example: A legacy ERP might rely on an x86-only database driver.
Example: CAD tools often depend on proprietary rendering libraries not ported to ARM.

2.3 Heavy x86-Specific Optimizations

Decades of work have gone into fine-tuning software for Intel and AMD CPUs. This includes:

Inline assembly using SSE, AVX, or MMX instructions.
Compiler optimizations specific to x86 microarchitectures.
Performance-critical kernels like FFTs or matrix math routines.

Porting such code to ARM isn’t trivial; the equivalents (like ARM NEON or SVE instructions) require manual optimization, not just recompilation.

2.4 Developer and Market Incentives

For many software vendors, the user base is still majority x86, especially on desktops. Until ARM achieves significant market share in PCs, companies feel little pressure to allocate resources toward ARM ports.

2.5 Availability of Compatibility Layers

Apple’s Rosetta 2 and Microsoft’s x86/x64 emulation on Windows ARM allow old software to run on new ARM devices. These stopgaps reduce urgency — vendors can postpone native ARM development because users can still run their apps, albeit with some performance loss.

3. The Impact on ARM Adoption

ARM’s challenges in desktops and laptops stem directly from the above. Let’s examine the real-world impact:

3.1 Slower Consumer Adoption

Consumers hesitate to buy ARM-based laptops (outside of Apple Silicon Macs) if critical apps run slower or fail under emulation. Gaming is a prime example: many PC games are x86-only and perform poorly on Windows ARM.

3.2 Enterprise Resistance

Enterprises running critical workloads on Windows or Linux x86 servers hesitate to migrate, since rewriting or re-validating complex business applications is expensive. ARM servers (e.g., AWS Graviton) are gaining traction mostly for cloud-native workloads, not legacy enterprise apps.

3.3 Ecosystem Fragmentation

When vendors release software for x86 but not ARM, users face an uneven landscape. Some apps are ARM-native, others rely on emulation, creating inconsistent performance experiences.

3.4 Performance and Battery Penalties

One of ARM’s biggest selling points in laptops is energy efficiency. Native ARM apps achieve excellent battery life and performance. But emulated x86 apps consume more power and run slower, undermining the very advantage ARM promises.

4. Case Study: Apple’s ARM Transition

Apple’s move from Intel to ARM (Apple Silicon M1/M2/M3 chips) is the most successful example of an x86-to-ARM transition. Why did it work?

Universal Binaries: Apple encouraged developers to compile both x86 and ARM versions of their apps into a single binary.
Rosetta 2: Apple built a highly efficient translation layer that runs x86 apps with minimal slowdown.
Incentives: Apple Silicon chips provided a clear performance boost, motivating developers and users alike.
Control: Apple owns the hardware, the OS, and the developer tools, allowing a tightly integrated ecosystem.

This shows that ARM adoption can succeed if the ecosystem push is strong, compatibility is smooth, and native performance is superior.

5. Case Study: Windows on ARM

Microsoft’s approach highlights the difficulties:

Early ARM-based Windows devices (like Surface RT) suffered because apps weren’t available.
Even with emulation, many performance-sensitive apps and games performed poorly.
Developers had little incentive to port apps, since the user base was small.

Only recently, with Qualcomm’s Snapdragon X Elite chips and improved Windows emulation, has the Windows-on-ARM story started looking promising. Still, the ecosystem gap remains wide compared to Apple’s more controlled environment.

6. ARM in the Cloud

Interestingly, ARM adoption is thriving in cloud computing:

AWS Graviton processors deliver significant cost and efficiency gains for cloud-native workloads.
Cloud-native software stacks (written in portable languages like Go, Java, and Python) are far easier to recompile and deploy on ARM.
Unlike desktops, cloud workloads are less dependent on binary-only legacy applications.

Here, the lack of heavy legacy baggage makes ARM adoption much smoother.

7. Future Outlook: Will ARM Overtake x86?

7.1 The Case For ARM

Performance per watt advantage is undeniable.
Apple’s success shows users will embrace ARM if the transition is handled well.
Cloud adoption is accelerating, which could trickle down to enterprises.

7.2 The Case Against ARM

Software inertia: Some legacy apps may never be ported.
Gaming ecosystem: Heavily x86-centric, with major investment in DirectX/x86 optimization.
Enterprise conservatism: Businesses avoid risky transitions unless absolutely necessary.

7.3 Possible Middle Ground

Hybrid models: ARM dominates mobile and cloud, while x86 retains parts of desktop/gaming.
Gradual erosion: Over time, as old software is phased out, ARM adoption could accelerate.

8. Conclusion

The reason older software hasn’t been rewritten for ARM is simple but powerful: legacy inertia. Codebases are massive, dependencies are entrenched, optimizations are x86-specific, and market incentives have been weak until recently. Compatibility layers like Rosetta and Windows emulation reduce urgency, allowing ARM devices to coexist with legacy x86 software instead of forcing rewrites.

The impact is clear: ARM adoption in desktops and laptops has been slower and patchier than in mobile and cloud, where legacy baggage is lighter. Apple has shown one path forward — strong ecosystem control, efficient emulation, and compelling hardware advantages. Microsoft and the broader industry are still catching up.

The long-term outcome depends on whether developers, enterprises, and consumers embrace the ARM-native future. If they do, ARM could eventually dethrone x86 even in domains where legacy software still rules. Until then, the coexistence of old x86 binaries and new ARM processors will continue to shape the computing landscape.

Aditya Pratap Bhuyan @adityabhuyan