X64 vs. X86-64

Attribute	X64	X86-64
Architecture	64-bit	64-bit
Registers	16 general-purpose registers	16 general-purpose registers
Memory addressing	Supports up to 64 TB of RAM	Supports up to 16 EB of RAM
Compatibility	Backward compatible with 32-bit software	Backward compatible with 32-bit software
Instruction set	Supports x86 and x87 instructions	Supports x86 and x87 instructions

Introduction

When it comes to computer architectures, X64 and X86-64 are two terms that are often used interchangeably. However, there are some key differences between the two that are worth exploring. In this article, we will compare the attributes of X64 and X86-64 architectures to help you understand their differences and similarities.

Overview

X64 and X86-64 are both 64-bit architectures that are used in modern computers. The main difference between the two lies in their origins - X64 is an extension of the X86 architecture, while X86-64 is a 64-bit extension of the X86 architecture. Both architectures are widely used in desktops, laptops, servers, and other computing devices.

Memory Addressing

One of the key differences between X64 and X86-64 architectures is their memory addressing capabilities. X64 architecture supports a maximum of 16 exabytes of virtual memory, while X86-64 architecture can address up to 256 terabytes of virtual memory. This difference in memory addressing capabilities allows X86-64 to handle larger datasets and applications more efficiently.

Registers

Registers are small storage locations within the CPU that are used to store data temporarily during processing. X64 architecture has 16 general-purpose registers, while X86-64 architecture has 16 general-purpose registers as well as 16 additional SSE (Streaming SIMD Extensions) registers. This additional set of registers in X86-64 architecture allows for better performance in multimedia and scientific applications.

Instruction Set

The instruction set is a set of commands that the CPU can execute. X64 architecture uses the x86 instruction set, which is a complex instruction set computing (CISC) architecture. On the other hand, X86-64 architecture uses the x86-64 instruction set, which is a reduced instruction set computing (RISC) architecture. This difference in instruction sets can impact the performance and efficiency of the CPU.

Compatibility

Both X64 and X86-64 architectures are backward compatible with 32-bit software, allowing them to run older applications without any issues. However, X86-64 architecture offers better performance when running 64-bit applications due to its larger memory addressing capabilities and additional registers. This makes X86-64 architecture a more future-proof choice for users who want to take advantage of 64-bit computing.

Operating System Support

Most modern operating systems, including Windows, macOS, and Linux, support both X64 and X86-64 architectures. However, some older operating systems may only support X64 architecture, limiting their compatibility with newer hardware. It is important to check the compatibility of your operating system with the architecture of your CPU before making a purchase.

Conclusion

In conclusion, X64 and X86-64 architectures are both 64-bit architectures that offer improved performance and efficiency over their 32-bit counterparts. While X64 is an extension of the X86 architecture, X86-64 is a 64-bit extension of the X86 architecture with additional features such as larger memory addressing capabilities and more registers. Both architectures are widely used in modern computing devices and offer backward compatibility with 32-bit software. Ultimately, the choice between X64 and X86-64 architectures will depend on your specific needs and requirements.