DESKTOP COMPUTING - Power User weighs the chips and dips into the Pentium debate

Many readers sent e-mail asking for advice after a column on how I chose a PC
for my office [GCN, March 23, Page 55].


I don’t believe Intel Inside and Pentium MMX mean much when it comes to purchasing
decisions. In the real world, there’s no more reason to pay extra for a Pentium MMX
PC than to insist on a V-6 engine vs. an equally powerful four-cylinder model in a car
that’s just for commuting.


Other makers’ chips are as fast as Intel Corp.’s or faster. And they cost
less, so PCs without the Intel Inside sticker have a lower price tag. But by all means,
get an Intel model if it has the best mix of features for the price.


Intel and its MMX clone licensees support 57 multimedia commands in their hardware,
which will run programs with lots of MMX functions much faster than computers that support
MMX-only software.


I still contend that MMX is mostly irrelevant. Only a few programs even look for MMX
capabilities in the processor, let alone support more than a few MMX commands. And if your
software doesn’t have encoded MMX commands, you will get zero benefit from having an
MMX chip installed.


Just about every machine sold today has an MMX processor, so it doesn’t make much
difference. But think about it when you consider upgrades from classic Pentium systems.


How about stepping up to the 400-MHz Pentium II chip now in PCs? Ask yourself how much
time you spend waiting for your PC to process a command before you can move on to the next
task. Most delays involve moving data between memory and hard drive or between your PC and
a remote Web server.


Unless you build gigantic spreadsheets, do nearly supercomputer-level analysis or
manipulate massive graphics and video files, you won’t find much real advantage in
doubling your clock speed from 200 MHz to 400 MHz.


One exception is heavy graphics users who need the 400-MHz or faster chip.


Meanwhile, Intel’s Merced processor, due early next year, will add a new set of
instructions and may even emulate the old x86 instructions in software.


If the emulation isn’t good, legacy software won’t run well. On the other
hand, if it runs too well, what incentive is there for developers to build programs based
on the Merced instruction set—programs that won’t run on older PCs?


Another Intel plan for a MMX/2 processor, code-named Katmai, would add 80 new 3-D
graphics functions. But with no software making much use of MMX yet, how much demand will
there be for the MMX/2?


Here’s a quick summary of the Intel Pentium chip’s history, because as you
can see, things have gotten confusing:


Also, Intel soon will release a Slot 2 processor for workstations.


Now let’s talk Intel competitors. Cyrix Corp. of Richardson, Texas, makes the 6x86
with a maximum clock rate of 150 MHz but greater efficiency than a same-rate Pentium.
It’s about equal to a 200-MHz Intel chip, has a 75-MHz bus and lacks MMX extensions.


The 6x86MX has a top 200-MHz clock rate and an Intel-equivalent rate of 350 MHz with
100-MHz bus. The faster 6x86MX chip incorporates 3-D graphics enhancements. Look this fall
for a Cyrix MXi chip equivalent to a 400-MHz Pentium II.


Advanced Micro Devices Inc. of Sunnyvale, Calif., makes the maximum 233-MHz K6
processor with 66-MHz bus and no MMX extensions. Other K6 versions go to 350 MHz with bus
speeds up to 100 MHz and MMX extensions plus 3-D graphics extensions. The planned K6+ 3D
will have a 400-MHz clock rate and 100-MHz bus to match Intel’s latest Pentium II.
  n


John McCormick, a free-lance writer and computer consultant, has been working with
computers since the early 1960s. E-mail him at powerusr@penn.com.

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