64-bit chips: Power to burn
- By Dan Carney
- Sep 24, 2001
"Wider is better," at least according to recent Pontiac TV commercials. The truth of that statement may be debatable with regard to sedans, but for computers, there is no doubt that a wider 64-bit data path can yield higher performance than a 32-bit processor.
It's not just because a 64-bit processor swallows data in bites twice as large as a 32-bit processor does. The newer chips can address, or directly access, greater amounts of data stored in the system memory—up to 18 exabytes. An exabyte is a billion gigabytes.
This added capability means that the system doesn't have to break big processing jobs into smaller chunks and quickly swap them in and out of memory to get the job done, as is sometimes necessary with 32-bit chips, which can only access 4 gigabytes of memory.
Processing data in such large chunks is not a new concept. Mainframes, minicomputers, workstations and enterprise servers have employed 64-bit designs for years. Compaq Computer Corp.'s Alpha, Hewlett-Packard Co.'s Precision Architecture RISC (PA-RISC), IBM Corp.'s PowerPC and Sun Microsystems Inc.'s UltraSPARC III are all 64-bit designs that federal agencies have been buying for several years.
However, personal computers, which far outnumber such high-powered workstations, have been limited to 32-bit designs. But with the recent introduction of Intel Corp.'s Itanium chip, 64-bit processing has taken its first step toward the mainstream. That's expected to cause significant changes in the high-end desktop computing market, not the least of which is greater affordability.
That isn't to say that 64-bit Itanium PCs are headed to desktops across the federal government. On the contrary, 64-bit desktop PCs probably wouldn't run any faster than 32-bit designs because the work isn't complex enough for the 64-bit design to have an advantage. "For 95 percent of different applications out there, the 32-bit product line is sufficient today," said Bob Barr, director of federal marketing for Dell Computer Corp.
So PC makers aren't rushing to build desktop PCs around the Itanium chip as they would with the latest version of Intel's Pentium processor. Instead, Itanium is going into servers and work.stations, which can benefit from the added power while sifting through immense databases or crunching numbers with Itanium's floating-point calculator.
Until now, users who run very large databases or computer-aided design applications have chosen one of the more established 64-bit chips that can support the 32G or more of main memory required for those applications, according to Nathan Brookwood, principal analyst at Insight 64, a consulting and research firm.
But although those proprietary computers are immensely powerful, they also cost much more than Intel-based systems. "Some of the difference is caused by the greater scale of those products and because they are using proprietary processors," Brookwood said. "The economics of developing and selling these processors is very different from Intel processors."
Another key benefit of Itanium is that although it offers maximum-strength workstation capability, it can also run a Microsoft Corp. Windows operating system, so users can keep using familiar personal productivity applications on their workstations.
That is important to federal users such as employees at the Air Force research lab in Rome, N.Y. "A lot of the machines for our scientists serve dual purposes: research and office productivity," said Fred Hall, chief technology officer with the service's information directorate.
"Itanium is a good first start, but it is not what is going to move the market to 64-bit computing," said John Enck, senior research director of servers and directory strategy for Gartner Inc. Later versions of the chip will make the move to 64-bit computing more compelling, but the move will be gradual, he said.
Future Intel chips will be faster than the initial Itaniums, which are code-named Merced. The Merced generation chip is aimed at large database servers, high-performance computing that exploits its fast floating-point capability and security services, said Lisa Hambrick, Intel's director of Itanium processor family marketing. Merced runs at 800 MHz and has a 4M cache on the processor cartridge.
The newer McKinley chip will run at faster clock speeds, move the cache onto the chip and improve the facilities for processing work in parallel.
"McKinley's performance will be about 50 percent to 70 percent better," Enck said.
With McKinley, company officials also aim to trim costs, so they can pursue the more price-sensitive work.station market, she said.
The chip after that one, dubbed Madison, will be a no-holds-barred performance chip that targets directory services applications, Web servers and cache servers, Hambrick said. "Intel wants this architecture to last for the next 25 years."
The Intel Bandwagon
Intel officials recognized that they lacked experience developing enterprise-class systems, so early in the Itanium design process, the company recruited HP to assist in designing the chip. "We wanted someone with enterprise experience," Hambrick said.
That cooperation produced a chip compatible with both the Intel architecture and the HP PA-RISC architecture. "PA-RISC lives on in the Itanium architecture," said Chuck Kausch, an HP technical consultant. "If you are a current [Unix] customer, you already have that compatibility."
Another boost may come from the infusion of help from Compaq. Before the announcement that HP plans to buy it, Compaq announced that it, like HP, would convert its proprietary Alpha 64-bit systems to use Intel chips in the future. And perhaps even more importantly for Intel, Compaq is handing over to the folks who made the Alpha chip one of the most powerful available today.
It is too early to say whether any Alpha design features will turn up in future Itanium chips because the designs planned through 2003 are pretty far along at this point, Hambrick said.
But the software side is a critical aspect in which the Alpha team can have an immediate impact. "Compilers are pretty important for 64-bit architectures," she said. "We will have their compiler people come over as well, and good compiler people are few and far between."
The planned move from Alpha to Itanium sounds good to customers in the Air Force's Joint Surveillance Target Attack Radar System surveillance program, who today use Alpha computers from Compaq.
"When we get ready to replace these computers in five years, we would consider Itanium," said Jim Kuhn, systems engineer on the computer replacement program for Joint STARS. "The reason for going with the commercial products [instead of custom-built computers] was that we could roll with the market."
Itanium-based computers are trickling into government offices as users size up the machines for possible widespread use. The research lab in Rome, N.Y., has ordered Dell Itanium computers for evaluation, Hall said. "We want to be sure they fit into the architecture here without any surprises."
The lab had a problem with Pentium 4 machines because of an in-house Oracle Corp. application. The application used an old Oracle plug-in, written when the Pentium 4 didn't exist. The plug-in didn't recognize the processor and had to be updated for the application to run.
Similar updates may be necessary for Itanium, so agencies such as the Rome research lab want to sort out all of the problems before rolling out the new systems across the board.
"Itanium is a Version 1.0 product, and typically you have to work out the bugs," Dell's Barr said.
Carney is a freelance writer based in Herndon, Va.