With Itanium, Intel proposes to examine programs when they are compiled into their executable form, and encode concurrent operations ahead of time. Intel calls this approach EPIC, for "explicitly parallel instruction computing," and it is the genuine difference between Itanium and AMDs x86-64. EPICs drawback is that the core of the Itanium no longer offers an upward-compatible path to existing x86 code, being designed instead with the simpler logic and the huge array of on-chip data registers that are the optimal environment for Itanium-style instructions. Upward x86 compatibility on Itanium processors is provided by included auxiliary hardware, but Itaniums actual speed with 32-bit x86 code has proved to be disappointing. Intel and its Itanium design partner, Hewlett-Packard, now position this facility as a convenience for running code that is either non-critical to performance or unavailable for porting to Itanium native form. Itaniums 32-bit x86 hiccup creates a major opportunity for AMD, which is betting that its cheaper to perform a miracle in hardwareand duplicate it in volume-produced microprocessorsthan to undertake the worldwide drudgery of revamping the software base.There is, however, a large degree of self-fulfilling prophecy in AMDs situation: In this casino, the other players side bets change the odds at the center table. If industry infrastructure vendors and software developers expect AMD to do well, then IT buyers will soon see a host of optimized driver software, middleware and applications for x86-64 that could easily add tens of percentage points to the overall performance of Opteron and Athlon 64 machines. Without that support, initial performance tests suggest that x86-64 wont have the compelling overall performance edge thats needed to overcome Intels market dominancepower that Intel is already rumored to be exercising in discussions with motherboard makers and others who are in a position to help or hinder AMDs momentum.
AMD is inviting enterprise IT buyers to set their own pace in a move to 64-bit systems at PC-market prices. The Opteron and its desktop-oriented sibling, the Athlon 64 (promised in September), throw all of AMDs talent at the challenge of running x86 instructions as quickly as possiblewhile at the same time introducing 64-bit hardware and instruction-set extensions.