MaximumPC 2006 06

B

ig brains or fast feet? Those are the two broad

choices for CPU architects. Some processors

achieve high performance by using extra-complex

logic. Others use simpler logic to race through cal-

culations at faster clock speeds. Either approach

works, but sometimes technology dictates which

method is better at a point in time.

This time, Intel is betting on the “big brains”

approach. Intel’s new microarchitecture, named Core,

is the foundation for new x86 processors coming in

mid-2006 and beyond. Don’t confuse it with today’s

Core Duo processors, which use the older Banias

(Pentium M) microarchitecture. Although the Core

microarchitecture is based on Banias, it’s a fresh

design not found in existing chips.

Core follows the “brainiac” philosophy. Brainiacs

are complex processors that run at slower clock

frequencies but perform more math than other

speed-demon processors. Intel’s previous NetBurst

microarchitecture was a speed demon. Its 31-stage

instruction pipeline was the deepest ever seen in a

general-purpose processor. Deeper pipelines enable

higher clock speeds, but NetBurst sprinted into the

brick wall of power dissipation.

By contrast, Core has a 14-stage pipeline.

That’s still pretty deep, so Core processors won’t

be slugs. And Intel has compensated by adding

more pipelines, widening some datapaths, and

making other improvements. NetBurst was a

three-way superscalar design, whereas Core is a

four-way machine. Core has 128-bit wide data-

paths for floating-point and multimedia instruc-

tions, whereas NetBurst had 64-bit-wide data-

paths. Core’s additional complexity delivers higher

performance at lower clock frequencies.

Core’s four-way superscalar design is a little

surprising. Executing four program instructions

per clock cycle is a relatively rare event. Most

superscalar processors struggle to average more

than 1.5 instructions per cycle. However, the wider

floating-point and multimedia datapaths should

measurably improve gaming performance, which

is critically important for home PCs. Intel has also

dropped Hyper-Threading for now, but it will probably

resurface in a future processor.

Overall, the Core microarchitecture makes

intelligent trade-offs and paves the way for Intel to

build multicore processors with two, four, or even

eight cores in the near future. It also pressures

AMD to do something marvelous with its own

revised microarchitecture, expected this summer.

Tom Halfhill was formerly a senior editor for Byte magazine

and is now an analyst for Microprocessor Report.

Intel’s Core

is a Brainiac

TOM

HALFHILL

FAST F/RWARD

JUNE 2006 MA XIMUMPC 9

Quad Cores Are on the Way!

Four core and five years ago...

W

indows Vista will support hybrid hard drives, which augment tradi-

tional platter storage with onboard fl ash memory. This small cache of

non-volatile memory will reportedly allow massive speed increases while

consuming signifi cantly less power. The problem is that Microsoft is depen-

dent on drive manufacturers to make the drives, and cost issues could be

a deterrent. Intel has devised a workaround of sorts—adding fl ash memory

directly to the motherboard chipset.

Dubbed Robson, Intel’s hplatform acceleration technologyv could consist

of either a fi xed amount of memory or an upgradeable socket. The benefi t

of Robson would be improved hard drive performance, without requiring a

special hybrid design. It should perform like Windows’ Prefetch, placing com-

monly accessed fi les and boot fi les in the cache, for quick access. Robson

could also allow drives to remain spun down, cutting down on noise and heat,

and saving energy. Intel is reportedly readying Robson for a 13 release along-

side its new Conroe CPU.

Intel’s Flashy New Technology

If Intel has its way, we’ll all soon be running onboard memory—

on our motherboards

Preview

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ur 200 Dream Machine (aka DM8)

sported two dual-core CPUs—for a

total of four cores—and it was bad to the

bone. Many readers coveted our quad-

core rig, and we can’t blame @em. The

good news is that in 200, quad-core

CPUs are coming to the desktop (fi nally).

According to a report in Digitimes ,

both AMD and Intel are prepping

quad-core CPUs for release in 11 of

200. Intel’s processor is code-named

+entfi eld and will be manufactured on a

6nm process using the company’s new

Conroe microarchitecture. AMD’s new

processor will be christened +L, and

will be a Socket AM2 part manufactured

with a 90nm process.