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What is meant by "Superscalar"

J

Jacky Luk

Jan 1, 1970
0
Pentium 4 is refered to as superscalar. What is meant by that? Thanks
Jack
 
J

John Jardine

Jan 1, 1970
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Jacky Luk said:
Pentium 4 is refered to as superscalar. What is meant by that? Thanks
Jack
It's what I know as "bollocks". It's something their marketing people have
dreamed up because the word sounds hi-tech.
regards
john
 
M

Mark Little

Jan 1, 1970
0
Jacky said:
Pentium 4 is refered to as superscalar. What is meant by that? Thanks
Jack

A superscalar architecture is a uniprocessor that can execute two or more
scalar operations in parallel. A scalar process consists of sequential
operations that cannot be parallelised or vectorised.

Hope this helps,
Mark
 
J

Jacky Luk

Jan 1, 1970
0
I feel a little hunch that "superscale" is exactly the same as
hyper-threading which is redundant....
 
J

Jani Miettinen

Jan 1, 1970
0
Jacky Luk said:
I feel a little hunch that "superscale" is exactly the same as
hyper-threading which is redundant....

They are not the same. Superscalar is older than hyper-threading,
and as most (probably all) of today's processors in desktop
computers are superscalar, only some do hyper-threading.

Hyper-threading differs from superscalar in that hyper-threading
allows the processor run operations parallel on _thread_ level
whereas superscalarity allows processor execute several
instructions of _one_ thread at once.

I don't know the details of hyper-threading, but I do know that
it's not exactly the same thing as superscalar. However, as you
might have concluded from the previous statement, they do have a
lot in common, so you are not entirely mistaken, either.
 
K

Keith R. Williams

Jan 1, 1970
0
They are not the same. Superscalar is older than hyper-threading,
and as most (probably all) of today's processors in desktop
computers are superscalar, only some do hyper-threading.

Correct. I don't belive any x86s (for instance) are simple scalar
processors anymore. Of this class only some Pentium 4's are
Simultaneous Multi-Threading (SMT). Hyper-threading is hyper-
marketeer-speak.
Hyper-threading differs from superscalar in that hyper-threading
allows the processor run operations parallel on _thread_ level
whereas superscalarity allows processor execute several
instructions of _one_ thread at once.

SMT doesn't disallow simultaneous operations (super-scalar) on
different threads.
I don't know the details of hyper-threading, but I do know that
it's not exactly the same thing as superscalar. However, as you
might have concluded from the previous statement, they do have a
lot in common, so you are not entirely mistaken, either.

Basically, super-scalar processors are those that have more than one
execution unit that can operate simultaneously (I.e. more than one
instruction operating at a time). Multi-threading processors track the
state of more than one process/thread simultaneously. The idea behind
super scalar processors is to execute more than one instruction at a
time (add in "fully-pipelined" as a modifier to super-scalar and one
can execute more than one instruction per clock). The idea behind
multi-threading is to keep the processor busy (the second thread) when
one thread has a pipeline stall.
 
B

BananaPannaPoe-

Jan 1, 1970
0
<architecture> A superscalar architecture is a uniprocessor that can execute
two or more scalar operations in parallel. Some definitions include
superpipelined and VLIW architectures; others do not. Superscalar
architectures (apart from superpipelined architectures) require multiple
functional units, which may or may not be identical to each other. In some
superscalar processors the order of instruction execution is determined
statically (purely at compile-time), in others it is determined dynamically
(partly at run time).

Refers to microprocessor architectures that enable more than one instruction
to be executed per clock cycle. Nearly all modern microprocessors, including
the Pentium, PowerPC, Alpha, and SPARC microprocessors are superscalar.
 
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