X64 instruction set

AMD64 instruction set is suitable for Athlon 64, Athlon 64 FX, Athlon 64 X2, Turion 64, Turion 64 X2, Opteron and newer Sempron and Phenom processors. Before the appearance of x86-64, Intel and Hewlett-Packard jointly designed IA-64 architecture, but this 64-bit architecture is not compatible with x86, the market response is relatively cold, and it is also subject to a number of patents, which makes other manufacturers unable to imitate it. AMD64 architecture compatible with x86 came into being. As the name implies, its main features include supporting 64-bit general-purpose registers, 64-bit integer and logic operations, and 64-bit virtual addresses. Designers have also made many improvements to the architecture, and some major changes are as follows:

Add register

Address width extension

SSE2, SSE3 instructions

"NX-bit": One of the characteristics of AMD64 is that it has a "no execution, NX bit", which can prevent worms from attacking in the way of buffer overflow (also called buffer overflow attack). AMD64 represents AMD giving up the consistent style of following Intel standards, and choosing to expand the x86 architecture to a 64-bit version just like expanding 16-bit Intel 8086 to a 32-bit Intel 80386, which is compatible with the original standards.

AMD64 architecture adds a 64-bit register to IA-32, and is compatible with earlier 16-bit and 32-bit software, so it is easy to convert the existing x86-oriented compiler into AMD64 version. In addition, NX bit is also one of the notable features.

Many people think that a 64-bit RISC chip like DEC Alpha will eventually replace the existing outdated and changeable x86 architecture. But in fact, the application software designed for x86 system is too huge, which is the main reason why Alpha can't replace x86. AMD64 can effectively migrate x86 architecture to 64-bit environment and be compatible with the original x86 applications.