Understanding the Core Differences Between x86, x64, and ARM: Implications for Software Compatibility

Introduction

Architecture Designx86, x64, and ARM are three major processor architectures, and their core differences lie in the instruction sets and data processing capabilities. x86 is a traditional 32-bit architecture represented by Intel and AMD processors, excelling in multitasking and complex computations. x64 is the 64-bit extension of x86, supporting larger memory and more efficient computations, suitable for high-performance computing and server applications. ARM, on the other hand, is a lightweight 32-bit architecture known for its low power consumption and high energy efficiency, widely used in mobile devices and embedded systems. These architectural differences determine the compatibility and performance of software across different platforms.

Instruction Sets and CompatibilityDifferent architectures use different instruction sets, which directly affect software universality. x86 and x64 utilize complex CISC (Complex Instruction Set Computing) instruction sets, while ARM employs a simplified RISC (Reduced Instruction Set Computing) instruction set. Although x64 can run most x86 software, it is not fully compatible. The ARM architecture has even greater differences from x86/x64, requiring software to be recompiled to run on ARM platforms. This difference in instruction sets complicates software portability across architectures, impacting software universality.

Application Scenarios and Performancex86 and x64 architectures are suitable for applications requiring high computational power and large memory, such as desktop computers, servers, and workstations. ARM architecture is more suited for low-power applications in mobile devices, such as smartphones, tablets, and IoT devices. In terms of performance, x64 performs better in handling complex tasks, while ARM has advantages in energy efficiency. These differences in application scenarios and performance further affect software universality, making software developed for specific architectures difficult to use across platforms.

Process

In the various computing devices we encounter daily, such as personal computers, mobile phones, and servers in data centers, they all rely on a common key component—the Central Processing Unit (CPU). However, despite these devices being equipped with CPUs, they often need to run their specific software programs. For example, applications designed for the Windows operating system typically cannot be executed directly on mobile devices; similarly, executable files based on ARM architecture cannot run on traditional x86 servers without the corresponding hardware support. The fundamental reason for this phenomenon lies in the differences in the CPU architectures used by these devices.

So, what are x86, x64, and ARM? Why can’t a program run across them? Today, we will delve into this topic.

1. What are x86, x64, and ARM?

In simple terms: they are different CPU instruction set architectures (ISA). Just like different languages have different grammatical rules, CPUs also have their own “syntax rules”.

1) x86 (32-bit) • Invented by Intel, primarily popular in PCs (personal computers) and servers. • Representative CPU brands include, but are not limited to, Intel’s Core series and AMD’s Ryzen series. • Being 32-bit, it supports a maximum of 4GB of memory.

2) x64 (x86-64 / AMD64, 64-bit) • Developed based on x86, supports larger memory (theoretically up to 256TB). • Currently, the vast majority of personal computer processors on the market adopt a 64-bit architecture design. • Can simultaneously execute 32-bit programs (provided the operating system can provide the necessary support).

3) ARM (King of Mobile Devices and Low Power) • Designed by ARM Holdings, licensed to various manufacturers. • Features: With its excellent low power characteristics and high energy efficiency, it is an ideal choice for smartphones, tablets, and various embedded devices. • Typical representatives include Apple’s M series, Qualcomm Snapdragon series, and Huawei Kirin series, all of which are prominent chip platforms in the current mobile device field.

Architecture	Main Uses	Characteristics
x86	PC, old servers	Classic, mature
x64	Modern PCs, servers	High performance
ARM	Mobile, embedded, IoT	Low power, lightweight, efficient

2. Why can’t an executable file run across architectures?

Because they use differing machine languages. Each computer architecture has its unique instruction set format, for example:

Operation	x86 Instruction	ARM Instruction
Increment Register by 1	<span>INC EAX</span>	<span>ADD R0, R0, #1</span>

Although they mean the same, the syntax is completely different. The compiler converts code written in high-level languages into machine instructions that can be understood and executed by the CPU.

int a = 1;
a++;

• • ✔ Compiled on x86 → generates x86 machine code
• • ✔ Compiled on ARM architecture platform, creating corresponding ARM format machine instruction code.
• • ❌ x86 machine code taken to ARM → CPU completely cannot understand!

🔧 This is why different architectures require separate compilation.

3. How to make a program run across architectures?

There are actually three methods:

✨ 1) Multi-architecture Compilation (Most Common)

For example, programming languages like Go, Rust, and C/C++ have cross-platform compilation capabilities.

gcc hello.c -o hello_arm -march=arm
gcc hello.c -o hello_x86 -march=x86-64

You will receive two files, each suitable for execution on ARM and x64 devices, respectively.

📌 2) Virtual Machines / Bytecode (Java, .NET, Python)

These languages do not generate machine code directly but first compile into an intermediate layer of bytecode, which then needs to be interpreted and executed by a virtual machine.

• • Java’s <span>.class</span> files can run cross-platform
• • Python scripts can also run cross-platform

⚠️ But the prerequisite is: the virtual machine itself must be compiled for the corresponding architecture.

🪄 3) Emulation (e.g., QEMU, Rosetta 2)

By simulating the behavior of the target CPU, allowing the program to “think” it is running in a native environment:

• • Performance usually suffers (10% to 50% loss)
• • Commonly used during the debugging phase of development or during system migration (e.g., allowing Apple Silicon Macs to run applications originally designed for Intel architecture).

4. Summary

Question	Explanation
x86?	32-bit PC architecture
x64?	64-bit extension of x86
ARM?	Low power, mainstay of mobile devices
Why can’t programs be universal?	Each CPU instruction set is different
How to achieve universality?	Multi-architecture compilation / Virtual machines / Emulators

👉 In summary: Whether a program can run depends not only on the operating system but also on the CPU architecture!

Many people ask:

Isn’t the ARM architecture processor specifically designed for mobile devices? Why has Apple also adopted ARM architecture in its MacBook series, and its performance surpasses many x64-based laptops?

This is not due to a sudden significant improvement in the ARM brand itself, but rather a result of a clear strategic plan and design philosophy combined with substantial investment in R&D.

5. ARM’s Design Philosophy: Low Power First, Not Poor Performance

ARM was originally aimed at embedded and battery-powered devices, with core goals of: • Power saving • Small chip area • Low cost • High energy efficiency (performance per unit power)

In other words: doing more with the same power consumption, rather than “piling on performance at any cost”.

In contrast, traditional x86 chips often operate under the philosophy that:

As long as performance is significantly enhanced, it is worth the additional power consumption.

This explains why personal computers and server devices must be equipped with cooling fans and high-power power supplies, while smartphones can achieve fanless designs and operate silently.

6. Why can Apple make ARM outperform x64?

Apple’s M1/M2/M3 can “outperform” many x64 laptops because it is not a typical ARM chip.

🍏 Apple has accomplished several things that others have not:

1) Self-developed high-performance ARM cores Most manufacturers of ARM-based devices prioritize energy efficiency, while Apple has invested substantial resources in developing high-performance core units on the ARM technology platform, enhancing computational performance while ensuring energy utilization efficiency.

2) Unified Memory Architecture (UMA) CPU, GPU, and Neural Engine (NPU) all use the same high-speed memory for data exchange and sharing.

• • Traditional x86: CPU and GPU memory are separate → data needs to be copied (slow)
• • Apple M chips: shared memory across the chip → zero-copy, extremely low latency

3) Deep optimization of software and hardware integration

• • macOS is restructured from the ground up for ARM
• • The Xcode compiler is specifically optimized for Apple M series chips.
• • System APIs are deeply bound to hardware features

This is akin to: while others use conventional weapons in battle, Apple independently developed a complete set of equipment systems and established corresponding training systems.

7. Why can’t all ARM outperform x64?

Because ARM is an architecture license, and implementations vary widely.

Chip Direction	Representative	Design Goals
Mobile ARM	Snapdragon, Kirin, MediaTek	Power saving as the main goal
Embedded ARM	STM32, Raspberry Pi chips	Low cost, low power
High-performance ARM	Apple M series	Performance + Energy Efficiency
High-performance x64	Intel, AMD	Extreme performance

Therefore: ❌ One cannot claim that mobile ARM chips are “weak in performance”❌ It is inappropriate to compare lightweight laptops constrained by x64 architecture with devices equipped with fully capable M processors.

Comparisons must be made under the same design goals to be meaningful.

8. Summary: Why can ARM defeat x64 on computers?

Perspective	ARM (Apple’s Approach)	x64 (Traditional PC)
Core Design	High energy efficiency	High power for high performance
Source of Advantage	Self-developed architecture + UMA + system-level optimization	Mature ecosystem, strong universality
Replicability	Difficult, very difficult (requires full-stack software and hardware capabilities)	Numerous manufacturers, open ecosystem
Future Trends	Rapid expansion into PC, server, and AI fields	Facing energy efficiency bottlenecks and competition

👉 ARM is not just for mobile; Apple has officially brought ARM into the era of high-performance computing.

Conclusion: A deep understanding of CPU architecture knowledge is key to understanding software compatibility, performance optimization, and future computing development directions. For software engineers or computer users, understanding “why certain programs cannot run smoothly on specific hardware” will greatly reduce the obstacles encountered in technical exploration and application.

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