For
the first time since the transition from 16 bit to 32 bit,
Intel is now making the break to a new 64 bit architecture.
Intel's first IA-64 (Intel Architecture-64) processor
code-named Merced will be arriving in the second half of
1999; Merced is being co-developed by HP. But even with the
arrival of Merced, Intel will continue to enhance their IA-32
processors--i.e., the Pentium II family (Celeron and
Xeon) processors.
The Merced will introduce a new buzzword to the CPU
world: EPIC, which stands for Explicitly
Parallel Instruction Computing. In order to maximize a
system's performance, it isn't enough to simply increase the
processor's raw clock speed.
IA-32 processors use dynamic branch prediction to
"look ahead into the future." Branch prediction
means the CPU is constantly attempting to anticipate the
next instruction before it actually occurs. Add
"dynamic" to the equation and you have a processor
that will analyze the history of instruction flow and
attempt to predict the next instruction.
But there's a limit, in terms of hardware, of how far the
CPU can predict. EPIC will attempt to overcome this barrier
by embedding the possible branches into each instruction
set. The compiler will bundle this data along with a set of
instructions into a large packet known as a long instruction
word. With a little help from the compiler, the Merced will
be able to arrange instructions in the most efficient way.
Of course, it remains to be seen how fast the software
industry (read Microsoft) can transition to EPIC. The
migration from 16 bit to 32 bit isn't completed yet; there
are still millions of Windows 3.x users out there. And even
today's Windows 95/98 is a hybrid 16/32 bit operating
system. But Microsoft is committed to supporting Merced in
NT 5.0 when the processor debuts in 1999.
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