Sun and AMD are to tighten their co-operation, focusing on the internals of AMD's flagship Opteron processor, according to Sun - though AMD has yet to make a definitive statement on the matter. Instead, AMD said that the two already co-operate on both technical and promotional levels.

David Yen, boss of Sun's scalable systems group, has reportedly said that that the two companies' collaboration will result in joint work on the 64-bit processor. He said that it was a natural evolution of the relationship; Sun also has experience of building high-end processors.

So far, Sun has released an Opteron-based workstation and provided AMD with technical advice on how best to make its chip work in a workstation.

Previous joint efforts between Sun and AMD have been of a similar nature and have not touched the insides of the chip. However, AMD, like many chip-making companies, has been forced to build alliances to help it defray the huge costs of designing processors and the associated multi-billion dollar fabrication plants required to manufacture them.

According to Sun, enterprises are now ready to buy Opteron-based servers so it presumably this as the right time to issue such a statement.

The background to the announcement includes joint participation in the HyperTransport Consortium, the group that promotes the chip-to-chip link used by the Opteron, among others. Last year, Sun started selling Opteron-based servers, following an announcement back in 2003 of a strategic alliance between the two companies.

Sun's statement at the time said that: "The alliance plans to also include long-term joint technology development to create future hardware and software offerings."

That statement's only mention of collaboration at the chip level was that "the parties will also collaborate on coherent HyperTransport technology implementations". It also said that Sun was to deliver new AMD Opteron processor-based Sun Fire servers, and versions of Solaris, Linux and Java. Analysts at the time saw the relationship as a natural development given that they both were and remain in competition with Intel.

The latest fruit of that relationship was Sun's announcement in April this year of its first dual-core Opteron-based server. Sun said: "The Sun Fire(TM) V40z server powered by AMD64 dual-core technology, is an enhanced four-socket, eight-way server that integrates four microprocessors - each with two complete CPU cores."