64-Bit CPUs: What You Need to Know - Page 2

-64 & Itanium">

Intels IA-64 (née Tahoe) architecture had a gestation period longer than that of an elephant. After first announcing their cooperation in 1994, Hewlett Packard and Intel said the first offspring of their matrimony would arrive "not before 1998," a prognostication that certainly proved to be true. In reality, the design was even longer in the making, for Intel and HP had stealthily begun working well before their mid-94 announcement.

Ten years and 325 million transistors later, we behold Itanium (all the good names were taken). Originally code-named Merced, Itanium is the first-born of the IA-64 family and our first real look into how well IA-64 will--or wont--work. (The subsequent offspring code-named McKinley, Madison, and Deerfield, are covered later in this article.) First and most obviously, Itanium, like all IA-64 processors, is not an x86 chip. It is a clean break from the long and legendary x86 (or IA-32, in Intel parlance) architecture that Intel invented, seemingly back when Earth was still cooling, and which propelled the Santa Clara company to such heights. Yes, Itanium is able to run x86 code in backward-compatibility mode, but that compatibility is tacked on; in its element, Itanium and all IA-64 chips are nothing at all like Pentium.

Thats both good news and bad news, as we shall see. Its good to be free from the tyranny of the x86 architecture, considered by many programmers to be the worst 8-bit, 16-bit, or 32-bit (take your pick) CPU family ever developed. That it should have succeeded so spectacularly is enough to shake ones faith in divine forces. The bad news? IA-64 leaves behind everything that made x86 chips ubiquitous, and presumably replaces it all with new bugs, new quirks, and new head-scratchers, leaving us to wonder, "why the hell did they design it that way?"