ATX-- Intel reinvents the PC

by Alan Zisman (c) 1996. First published in Canadian Computer Wholesaler, July 1996

It?s 1996; if you?re running a PC, you?ve got a machine that, in some ways, has evolved a long way from IBM?s original Personal Computer in 1981.

That machine shipped with a massive 16kb of ram, and an Intel 8088 processor, running at a speed of 4.77 mhz.?over twice as fast as an Apple II of the same era. You could avoid paying extra for a floppy disk drive, and use the built-in Basic, loading programs through a cassette tape port. (Nobody did that, though, as far as I can tell).

PC DOS 1.0, the product (more or less) of fledgling Microsoft (as was the built-in Basic), lacked support for directories, or even commands we take for granted such as CLS to clear the screen. No mouse support, no graphical user interface, but there was a game called Donkey, where you tried to get an incredibly ugly donkey across a busy highway? rumoured to be the last program completely written by Bill Gates.

Fifteen years later, we?ve had 286s, 386s, 486, and now Pentium and Pentium-Pro style processors, with speeds now approaching 200 mhz. Even the humble 486-66 I?m using right now, when measured by the old Norton Utility SI (System Information), clocks in over 100 times as powerful as that initial PC. Increasingly common ram of 16 meg offers 1000 times as much memory as that initial computer. That initial computer lacked hard drives? soon, 5 to 10 meg units became available, for $1000 or more. Today, you can buy a gigabyte drive?1,000 megs, for $300 or so.

And while DOS is still around, it?s increasingly well-hidden, or replaced entirely, with much more attractive and easier to use interfaces. No more Donkey game, however.

Still, in many ways, if you open up the box, you still get basically the same design as on that original PC? a motherboard, a power supply with a fan in the back, right-hand corner, drive bays, cards, ribbon cables. More sophisticated parts, but organized identically to that ancient ancestor. Even a new tower case just turns it all on its side.

Intel tries something new

Intel, with the bulk of the market for CPU processor chips, has, increasingly, also been selling the support chips and the motherboards?allowing computer manufacturers to bring products to market with less (or even no) research?buy the parts from Intel, slip them into a case, paste your name on front, and distribute them as your own.

Some have questioned their motivation?while profits on CPUs can be 50% or more, there?s much less profit on the sale of a motherboard. But this way, Intel ensures that their chips go into well-designed units. What?s more, they make sure that OEMs aren?t selling computers with chips from one of several companies cloning Intel?s designs.

Whatever their motivation, their new ATX designs are becoming increasingly common, and at last, provide an update to that 15 year old PC design.

What?s more, Intel has made the ATX specification public?other motherboard manufacturers can design and sell their own models, compatible with Intel?s design (check or for more details).

What?s inside the case?

Think of an ATX motherboard as a traditional baby-AT motherboard that?s been rotated 90 degrees, so the long side runs parallel to the back of the case. Then, the expansion slots get flipped again, putting them back into their traditional back-to-front orientation.

This simple reorganization provides a number of benefits.

In the old-style motherboards, the CPU and ram often had to be placed behind the expansion slots?as a result, many of the slots could only hold short cards. Users wanting to add longer cards for video capture or multimedia might be out of room. Alternatively, the CPU or ram could end up underneath the drive bays, making it difficult to access. In either arrangement, air flow is a problem, leading to potential overheating.

The new geometry of the ATX eliminates both of these arrangements?long cards can be used in all slots, and the ram and CPU can be more easily accessed. A new style power supply blows air over the CPU for better cooling, without needing an additional fan.  (It should be quieter, too). More IO options can be built into the motherboard, allowing both traditional and new-style ports to be included? the upcoming Universal Serial Bus, and even TV input can be easily added to the double-height IO panel.

Low-end models support unified memory design?widespread on Macs, this shares the motherboard?s ram between the CPU and the video system. With more options built-in, fewer cables are needed? the net result is a motherboard and computer that are less expensive to produce, and that give off fewer electronic emissions?a requirement of the regulatory agencies. Similarly, floppy drive and twin EIDE hard drive are built right into the motherboard, right behind the drive bays, enabling short connections that are cheaper and allow higher performance.

Industry shakeup

Intel?s efforts have been widely adopted?virtually all major PC manufacturers have begun offering ATX-style models in their current product line. Even traditional go-their-own-way companies like Compaq, are flocking to ATX, though, inevitably, with their own twist. It?s estimated that 16% of 1996?s computers will support this style, a percentage expected to grow to 64% by 1999.

Intel?s moves into the chipset and motherboard businesses, however, are decimating independent competitors, particularly in Taiwan. 80 Taiwanese companies have left the motherboard business, leaving only another 20 remaining. A year or two ago, there were 50 companies in Taiwan making chipsets. Today, there are about five.

Despite this, the survivors feel like they can both cooperate and compete with Intel?cooperate by not jumping ship with a major push to the PowerPC or use of CPUs from Intel competitors Cyrix or AMD ?most cloners feel like the bulk of the market wants ?Intel Inside?, so they have to remain true to that standard. But there?s still room to innovate and compete. Since the ATX specification is public, they can design their own variants, giving customers more features built in?such as multimedia using on-board Digital Signal Processing chips.

Is it still a PC?

The 486 motherboard on my desk is sitting inside an old Packard-Bell 286 case; it?s had 386-25 and DX-33 boards in it in between. But if I upgrade to a new generation Pentium or Pentium-Pro ATX-style motherboard, that case will have to go. I?ll need a new case and power supply.

Despite that, the ATX is still compatible with much of the standard PC add-ons? my ISA cards will still work, along with my floppy and hard drives. (I?d need to replace my VLB video adapter with a PCI model, but I?d have to do that anyway. Similarly, I?d need to replace my 30-pin ram with newer versions?something that again, I?d need to do in any event. In fact, I?d probably be best off simply getting a whole new computer, and giving this one to my kids!)

ATX motherboards are here now, supporting both Pentium and Pentium-Pro cpus, in both traditional single-processor, and high-end dual-processor designs. They are increasingly available both from Intel and a growing number of other manufacturers; and in computers sold by a wide range of companies, ranging from the well-known brands, to the clones. It?s not a total break with the PC?s past, but rather, is the logical next step in PC-evolution.

It?s a good bet that your next desktop computer will feature this design.

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Alan Zisman is a Vancouver educator, writer, and computer specialist. He can be reached at E-mail Alan