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
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
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.
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
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
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.
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
Donkey game, however.
Still, in many ways, if you open up the box, you still
the same design as on that original PC? a motherboard, a power supply
a fan in the back, right-hand corner, drive bays, cards, ribbon cables.
More sophisticated parts, but organized identically to that ancient
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
manufacturers to bring products to market with less (or even no)
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
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
common, and at last, provide an update to that 15 year old PC design.
What?s more, Intel has made the ATX specification
manufacturers can design and sell their own models, compatible with
design (check http://www.teleport.com/~atx or
for more details).
What?s inside the case?
Think of an ATX motherboard as a traditional baby-AT
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
into their traditional back-to-front orientation.
This simple reorganization provides a number of
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
short cards. Users wanting to add longer cards for video capture or
might be out of room. Alternatively, the CPU or ram could end up
the drive bays, making it difficult to access. In either arrangement,
flow is a problem, leading to potential overheating.
The new geometry of the ATX eliminates both of these
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
without needing an additional fan. (It should be quieter, too).
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
and computer that are less expensive to produce, and that give off
electronic emissions?a requirement of the regulatory agencies.
floppy drive and twin EIDE hard drive are built right into the
right behind the drive bays, enabling short connections that are
and allow higher performance.
Intel?s efforts have been widely adopted?virtually all
major PC manufacturers
have begun offering ATX-style models in their current product line.
traditional go-their-own-way companies like Compaq, are flocking to
though, inevitably, with their own twist. It?s estimated that 16% of
computers will support this style, a percentage expected to grow to 64%
Intel?s moves into the chipset and motherboard
are decimating independent competitors, particularly in Taiwan. 80
companies have left the motherboard business, leaving only another 20
A year or two ago, there were 50 companies in Taiwan making chipsets.
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
or use of CPUs from Intel competitors Cyrix or AMD ?most cloners feel
the bulk of the market wants ?Intel Inside?, so they have to remain
to that standard. But there?s still room to innovate and compete. Since
the ATX specification is public, they can design their own variants,
customers more features built in?such as multimedia using on-board
Signal Processing chips.
Is it still a PC?
The 486 motherboard on my desk is sitting inside an
286 case; it?s had 386-25 and DX-33 boards in it in between. But if I
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
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
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
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
It?s a good bet that your next desktop computer will
feature this design.