AMD64

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The AMD64 CPU architecture (codenamed "Hammer", and often referred to as the x86-64 architecture) represents AMD's entry into the 64-bit microprocessor market.

AMD64 represents a break with AMD's past behavior of following Intel's standards, but follows Intel's earlier behavior of extending the x86 architecture, from the 16-bit 8086 to the 32-bit 80386 and beyond, without ever removing backwards compatibility. The AMD64 architecture extends the 32-bit x86 architecture (IA-32) by adding 64-bit registers, with full 32-bit and 16-bit compatibility modes for earlier software. Even the 64-bit mode is largely backward-compatible, allowing existing tools targeting x86 (eg. compilers) to be retargeted to AMD64 with minimal effort.

This is in sharp distinction to Intel's competing IA-64 architecture, which makes a complete break from Intel's own x86 architecture.

AMD has released its first generation of AMD64 processors, under the names Athlon 64 and Opteron. The Athlon 64 (codenamed "ClawHammer") is designed for desktop and mobile computers, while the Opteron (codenamed "SledgeHammer") is intended for servers and workstations. The Opteron processor has been shipping since April 22, 2003. Several companies are shipping Opteron-based servers.

Table of contents

1 Operating systems
2 Intel EM64T
3 See also
4 External links

Operating systems

There are now (2004) fully-functional versions of Linux, OpenBSD, FreeBSD, and NetBSD available for the AMD64, along with working processors. An AMD64 version of Microsoft Windows is available as a pre-release version. Sun is also working on a port of its Solaris operating system to AMD64.

Intel EM64T

In the face of the competition from the AMD64, Intel released the EM64T architecture in February, 2004. This is a 64-bit chip which is largely instruction-set compatible with the AMD64, with very minor differences in implementation. It is expected that EM64T will be fully compatible with AMD64 in later revisions. EM64T is apparently based on an earlier specification of the AMD64 architecture, which AMD had released prior to the actual launch of the Hammer family of processors.