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-- by Jim Forbes
With 51 million desktop and mobile PC users armed with Pentium-based systems, Intel knows it needs a new hit to maintain its torrid growth and further feed the PC buying frenzy. To that end, the microprocessor titan will spend 1997 evangelizing a new PC multimedia technology that could change the way you work and play. It's called MMX, and it's arriving on Pentium desktops and laptops now.
MMX could well usher in a new generation of multimedia and communication applications-from advanced games to image, audio-processing and voice-recognition software-that stimulates even greater demand for new, high-performance PCs.
Before you embrace MMX, it's important to understand the technology's underpinnings.
The MMX-enabled Pentium (known as the P55C or "The Pentium Processor with MMX Technology") has 57 new instructions, which operate on packed data types using 64-bit registers. Each 64-bit register can hold 8 bytes, four words or two double words, and each data size can be treated as signed or unsigned.
Why is the 64-bit register so important? The answer is Single Instruction, Multiple Data (SIMD) parallel processing. For example, multiple pieces of data in the register can be processed simultaneously. In addition, the MMX instructions can either wrap around or saturate on arithmetic overflow or underflow-which simply means it can handle numbers too large or too small to be easily represented in binary. Saturation arithmetic, which isn't available in the rest of the Intel instruction set, is useful in preventing multimedia problems, such as color errors, when processing image and sound data.
Some experts say the combination of SIMD parallel processing and saturation arithmetic can dramatically reduce the instruction count for many media-processing operations, resulting in roughly a 60 percent performance boost over standard Pentium instructions, depending on the data size and the application. MMX can also help existing peripherals: Since MMX was designed to handle communications, it can, in some cases, boost programmable modems to faster speeds.
Marching to Intel's Tune
Most personal computer makers say they're eager to support MMX, especially because it requires few changes to motherboard design. MMX processors can be used in systems equipped with Intel core logic and Socket 7 sockets-the very same sockets used in most PCs shipped during the last two years. That will make it easy for PC manufacturers to make the switch to MMX. The first MMX systems, from Compaq, Dell, Gateway, Micron, Packard-Bell and Sony, among others, are expected to hit retailers' shelves this month. MMX will also hit the road in a new generation of multimedia laptops (see sidebar on this page)
Initially, computer makers will offer MMX only on higher-end systems that cost $2,500 or more, according to PC market analysts. The new machines will typically include 166MHz or 200MHz MMX-equipped Pentium processors with 6X (or faster) CD-ROM drives, at least 16MB of RAM, 1.2GB or 1.6GB hard drives, specialized 3-D graphics accelerators with 2MB of memory, a Universal Serial Bus and a full complement of standard or enhanced ports. At press time, Intel was said to be finalizing a labeling campaign, similar to "Intel Inside," that would make MMX systems easily identifiable to PC buyers.
MMX-enabled Pentium Pro microprocessors (code-named Klamath) won't likely arrive until the second half of this year. Klamath systems are expected to be bolstered by several additional Intel technologies, including an Advanced Graphics Port (AGP), a new 3-D accelerated video chip and other technologies. The AGP is particularly interesting. It's a new high-speed graphics bus that will support a new generation of 3-D graphics chips, and could in the longer term subsume the PCI bus. When Klamath systems arrive, industry experts believe they will start at $3,000 and drive prices for MMX Pentium systems below $2,000.
Who Needs Software?
While hardware vendors are embracing MMX, it's less clear when MMX-enabled software will arrive, especially MMX-enabled business software. On the plus side, MMX is completely compatible with existing operating systems because it reuses the existing Pentium floating-point register set and context switching. And even in the absence of MMX software, WINDOWS Magazine's lab has found some reason to celebrate MMX hardware: It will improve the performance of many existing applications.
Micron Electronics sent two Pentium desktop computers to our labs, a 166MHz machine and a 200MHz box. Each unit had an MMX-enabled Pentium processor. The computers were configured with a BIOS that supports MMX and non-MMX processors, allowing us to swap out the MMX processor for a non-MMX chip and get a true performance comparison.
The results were impressive, even for non-MMX applications. For example, in the case of the 166MHz Micron machine, we saw an average performance improvement (after three executions of a macro) of about 14 percent in Microsoft Word 7.0 and 9 percent in Microsoft Excel 7.0.
Our analysis of the 200MHz system offered similar results. The Word and Excel tests each showed roughly 12 percent improvement with the MMX processor. A review of Gateway's new entry in the MMX market showed comparable results (see review in sidebar "Pound for Pound, a Powerful PC")
The performance improvement in these non-MMX applications is, however, due to a boost in cache rather than the new Pentium's MMX capabilities. Indeed, the MMX-enabled Pentium has 16KB more L1 cache than a conventional Pentium.
How well will MMX applications perform on MMX chips? The answer is a bit hazy. The only test available at press time was a multimedia benchmark from Intel. Since this is Intel's chip, many would question the objectivity of the test. With that caveat in mind, we found that multimedia performance for the MMX-enabled 166MHz system improved almost two-thirds overall, with an impressive four-fold increase in image processing performance. We charted similar results for the 200MHz processor, with only slightly different numbers.
The Waiting Game
Despite the promising results of Intel's multimedia benchmark, it remains unclear when MMX software will arrive. Only a short list of software developers, including Adobe, Epic MegaGames, IBM, Microsoft and PowerSoft, have pledged at least some support for MMX. Microsoft, for one, says it will support MMX in its Direct3D, ActiveMovie and Visual C++ compiler, but admits it's still evaluating MMX support directly in Win95 and NT.
To be sure, MMX will find its way into some business applications, including teleconferencing products, Internet-enabled whiteboarding, personal messaging and a new generation of presentation graphics products. Specifically, future versions of Intel's ProShare videoconferencing product, IBM's VoiceType voice recognition software, Adobe's Photoshop and PhotoDeluxe, and Books That Work's Visual Home design program will all take advantage of MMX.
Early MMX converts are quick to praise its performance and the way it eases the development of new software games and communications-intensive applications. Epic MegaGames, for instance, says its forthcoming MMX action games will offer 16.7 million color modes-a whopping increase from the current 256-color limit.
The Bottom Line
By assuring operating system compatibility, Intel and its loyal following of hardware makers insist the combination of MMX and MMX-enabled software will deliver new levels of performance and functionality to homes, small offices and some corporate users. But until MMX becomes a standard for software development, Intel's multimedia nirvana won't likely be realized.
David Gabel, James Alan Miller, Martin Heller and John J. Yacono also contributed to this article.
Copyright © 1997 CMP Media Inc.