MMX: Marketing Hype, or Innovative Technology?

So, if you're thinking of buying a new PC, is a Pentium MMX worth the extra cost? Or should you wait for the next generation of MMX (the Pentium ll Processor) instead?

by Tina Lieu

Against a backdrop of falling PC prices and depressed sales, buyer anticipation of new PC models incorporating the MMX technology contributed to stranding Japan's PC vendors on top of worrisome high inventories. Faced with the task of selling off their non-MMX PC models while the new Pentium MMX machines were coming out put PC vendors in a no-win situation.

Lots of hardware, little software
In Japan, the official release of the Pentium MMX came almost simultaneously with announcements of Pentium MMX-equipped PCs by Dell Computer, Digital Equipment Corporation Japan, Gateway 2000 Japan, Hitachi, IBM Japan, Sanyo, Seiko Epson, and Toshiba. These frontrunners were quickly joined by NEC and Fujitsu, and other makers soon jumped on the bandwagon. The first wave of Pentium MMX PCs hit the Japanese market from late January to early February. (For a listing of Japanese MMX-equipped PCs currently on the market, see the expanded online version of this article on our website at http://www.computingjapan.com. -Ed.)

What effect are Pentium MMX computers having on the PC market? According to Katsushi Shiga, analyst at Dataquest (of the Gartner Group), "MMX technology will have a big impact. It enlarges the range of multimedia applications and widens the spectrum of users. By enabling [less powerful machines] to run applications like Adobe's Photoshop or Macromedia's Director, MMX will eventually allow more users to take advantage of this software. And in business, video conferencing will become a more common and casual affair."

Shiga dismisses the claim that MMX technology will enable Windows to erode the Macintosh's traditionally strong areas of DTP and multimedia. "Rather than steal share from the Mac, the MMX will broaden the range of PC users using multimedia."

"The MMX chip will gradually drop in price into the latter half of 1997. By the end of 1997, probably almost all new PCs on the market will be loaded with MMX. And MMX-optimized software will likely be bundled with those machines, thus further spreading the use of MMX and stimulating software developers to write software using MMX," says Shiga. He cautions, however, that "the software will take more time than the hardware to reach the market. It's rather hard to write software for MMX [and] adapting existing software to take advantage of MMX will be almost like rewriting it from the beginning. Software used by professionals, such as Photoshop 4.0, will be MMX-optimized first; software for amateur use will probably not become widespread until the fourth quarter of '97."

This is a point to bear in mind if you're in the market for a new computer. MMX technology instructions are only effective if you have software that is written to take advantage of them.

What's new?
The MMX Technology Pentium Processor is not so much a new MPU (microprocessor unit) as one that incorporates additional instructions and functions to improve the processor's efficiency and performance. The Pentium and Pentium Pro are highly complex chips, and making them more complicated would be extremely difficult without significantly raising the costs of the chip. So instead, Intel went back and simplified the instructions, adding four significant functions to the conventional Pentium processor.

First, Intel added a whopping 57 new instructions to the MPU. This new instruction set simplifies the work of the MPU and enables it to perform the same functions with fewer instructions. One example is the algorithms that take the inner product of vectors (a basic calculation needed for processing images, sound, and video); MMX technology reduces the instructions that need to be executed from 40 to just 13.

A second advance is implementation of "simple instruction multiple data" (SIMD), through which a single set of instructions can be applied to multiple data items. This enables data to be processed more efficiently and quickly in parallel (at the same time). Multimedia data processing involves a lot of time-consuming, compute-intensive loops, and running a bunch of them at the same time is more efficient.

-Home users targeted-

As mentioned in the article, Japanese PC makers were quick to announce Pentium MMX-loaded PCs after the Intel announcement. A survey of the PCs available as of mid-February at the MMX Convention in Tokyo showed that very few systems were marketed with a business focus; most of the desktop models had multimedia extras and were targeted for home use. Loaded with a DVD (digital versatile disc) player were Panasonic's Woody CF-200PDX with PD drive (DVD optional), Toshiba's Brezza 5200VMB (with an easy-to-use push button panel), and NEC's Cereb (with remote control, widescreen TV monitor, and wireless keyboard). IBM's Aptiva S-series B80, B85, and B95 models come with a joystick, and Mitsubishi's Apricot MS660 has an easy-to-use remote control.

Before MMX, for example, a register (a place in the MPU to hold data for processing) could only hold one pixel or audio byte per cycle. With SIMD, four to eight pixels can be operated on simultaneously in a 64-bit register. Where a conventional Pentium might only be able to show every fourth frame during video playback, MMX technology allows every frame to be shown, making for smoother viewing.

Third, the Pentium MMX chip has a larger cache (32K rather than 16K). This larger cache alone improves the processing speed of any application (not just MMX-optimized applications) by 10% to 20%.

The fourth advance is improved "branch prediction" efficiency. As Michael Aymar, vice president and general manager of Intel Corporation's Desktop Products Group, explains, "In the past, data had to go through a loop before being branched [sent] off on its way. Now, based on where other data was sent, the processor will prepare the data for a certain path before processing it [which] is efficient if the same operation is repeated." Since with multimedia data there are many repeated operations, this function can greatly improve performance.

Pentium MMX vs. PowerPC
Compared to a conventional Pentium processor of the same clock speed, a Pentium MMX processor yields higher performance (with MMX-optimized software, much higher). But how does the Pentium MMX compare with other chips, such as the PowerPC processor produced by Motorola and used by Mac compatibles?

Pentium chips are based on CISC (Complex Instruction Set Computing) architecture; PowerPC chips are based on RISC (Reduced Instruction Set Computing) architecture. One of the advantages that MMX technology brings to the Pentium chip is single-cycle instructions, something that is inherent to RISC architecture. According to Gary Montgomery, operations manager of Nippon Motorola Ltd.'s RISC/NetComm Operations, RISC means that instructions are single cycle, or pipelined to single-cycle instructions. All instructions are 32 bits long, and the CPU issues new instructions every clock cycle.

The number of registers is one important variable that determines how quickly and well a chip performs but, as Montgomery explains, "Once the number of registers in a chip is decided, it is very hard to change that number without also changing the architecture. When the PowerPC architecture was first designed, Motorola had the foresight to put in 32 registers, each double-precision 64 bits. That means a decimal with the accuracy of 26 places will fit in a register." And thanks to "register renaming," the PowerPC actually has more than 32 registers at its disposal (although the 32 are the only ones that programmers need to worry about).

Pentium chips, on the other hand, have only four 64-bit registers. While MMX technology is able to create four more "virtual registers" when running MMX instructions, only four registers are available for non-MMX processing.

For MMX 3D graphics processing - as in games - movement of polygons (i.e., figures) requires floating-point operations, but painting the polygons requires MMX instructions. Since floating point operations and MMX operations cannot share a register, the MPU must switch the registers back and forth between the two operations. This explains why 3D graphic performance is still relatively weak in the current version of MMX.

Asked what he thinks of Intel's Pentium MMX, Motorola's Montgomery laughs. "It's a marketing coup for Intel! MMX is just trying to do what the PowerPC already does. If you want to know what MMX is aiming for, look at a Macintosh."

Byte Magazine reported ("MMX: Better in Fits and Starts," February 1997) on a performance comparison test between a 200-MHz Pentium MMX, 200-MHz Pentium Pro, and 200-MHz PowerPC 604e running Adobe Photoshop 4.0, an MMX-optimized application. In five tests of common Photoshop functions, the PowerPC 604e beat the Pentium MMX in three of the five functions considered to be the most important: arbitrary rotate, unsharp mask (custom), and RGB to CMYK.

MMX-optimized software, now and later
Intel sees applications for MMX technology in multimedia-rich home applications such as video, image, and sound processing, and in office uses such as multimedia data on intranets and videoconferencing. MMX is, more than anything, aimed at improving performance of multimedia data processing; there are few spill-over benefits to programs like word processing and spreadsheets (except for the non-MMX related improvements of cache size and improved branch prediction).

At Tokyo's Intel MMX Technology Convention in February, Microsoft was not yet ready to announce when and how it intended to incorporate MMX technology into its future software releases. Over a dozen software makers were on hand, however, to demonstrate their MMX-optimized software (mostly music-composing programs, games, music videos, and educational CD-ROMs). Almost without exception, the makers said they planned to market products that were MMX-optimized but also playable on conventional Pentium machines.

- Don't try it! -

Can you buy a Pentium MMX chip and slot it into your current machine for a homemade upgrade? Not unless your system has a special motherboard with variable adjustable current. The Pentium MMX chip runs on a power-efficient 2.8 volts rather than the conventional Pentium's 3.3 volts. You'll fry your new Pentium MMX chip if you plug it into a conventional Pentium system's motherboard.

Sega Enterprises, Ltd., was at the convention demonstrating its fast-paced and popular "Cyber Troopers Virtual On," a 3D fighting game (ported from the arcade game version) that requires MMX technology to run. According to manager Hiroyuki Otaka, of Sega's PC division, "This game would have a very hard time running without MMX technology because it's extremely graphics heavy. It has double the graphics of the most graphics-heavy game currently on the market. This game [being demonstrated] is running on 32MB of RAM, but that's just the minimum. Ideally you'd want even more RAM." Otaka estimates that of the game software produced by Sega each year, about 60 titles are for use with their game console system, Sega Saturn, and only about a dozen titles are for PCs.

Asked about Sega's future plans for MMX-optimized games, Otaka says, "Sega is planning on putting out another ten titles from April that will use MMX technology, but those games will also run on non-MMX machines. Most of those will be 3D." Regarding the future of MMX and games, Otaka said that he'd like to see MMX catch on and spread, and that he hopes to see the Klamath [Intel's next generation of MMX chips] come out soon. He points out, however, that the speed of the CPU is only one of the factors that will improve PC gaming (advanced video cards and even cheaper RAM being others).

The next generation
According to an Intel spokesman, the chip formerly code named Klamath is now officially called the Pentium II Processor. In essence, it is a Pentium Pro with MMX technology added. Shipment of the Pentium II is scheduled to begin in the first half of 1997.

On the PowerPC side of the market, Motorola released a 240-MHz 603e chip for notebook computers in second-quarter 1996; the 603e is featured in Apple's new PowerBook 3400c series of notebooks. In February, Motorola released a technical paper on the next-generation chip which, according to Rieko Asanuma of Nippon Motorola Ltd., will be announced later this year. Motorola's Montgomery says this new chip is expected to be up to production standards by the third quarter of this year, and systems based on the chip are expected by year end.

And the playing field is growing. Exponential Technology of San Jose, California, has announced a microprocessor based on the PowerPC architecture that will run at 533 MHz. It is expected to be released in 1997.

Will the likely proliferation of MMX-required software spark another cycle of PC buying similar to the launch of Windows 95? Time will tell, but the next year or so looks to be an exciting time for the chip industry.

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