Abstract: What we are seeing today has probably never happened in the history of computing. Faster and faster CPU's are churning out of the fab plants at what seems like a weekly basis. Before we can even get out hands on the fastest processor out there, an even faster processor comes and takes its place before we know it!|
CPU / Processors >
Cyrix/VIA MII-PR433 Processor
What we are seeing today has probably never happened in the history
of computing. Faster and faster CPU's are churning out of the fab plants at what
seems like a weekly basis. Before we can even get out hands on the fastest
processor out there, an even faster processor comes and takes its place before we know
it! As we all know, this is because AMD had at long last reached
a stage where their products were poised to do battle with the pride of Intel,
the Intel Pentium III line of CPUs.
Socks were knocked off at Intel and they just
couldn't believe that after all these years of AMD playing catch up with Intel,
AMD had finally had the technology to beat Intel at their own game with their
release of the Athlon processor. High end CPUs with speeds of 800MHz+ are being
released so frequently that it is almost boring to keep up with. The fanfare of
a processor launch isn't what it used to be.
The competition has become so fierce that it has
come down to a company releasing a CPU that is only 50MHz faster in clock rate
than its competitor just to be crowned "speed king" for the time being. Currently, no
one foresees a true competitor to the Intel Pentium III or the AMD Athlon CPUs.
Transmeta's Crusoe is making waves in the background, but as this CPU has yet to
hit mainstream, it will take sometime to judge whether or not the Crusoe is able
to share the same space with AMD or Intel.
So while this battle of "who's
better, who's best" goes on in the spotlight, VIA-Cyrix has been working its
own processor. No, not at the high-end where any chance of getting a foothold in
the market looks grim, but at the low end consumer level where the this bloodbath
is relatively less bloody. It is the upcoming "Joshua" processor which is
slated for release in few days this February. The "Joshua" is targeted to
compete directly with the Intel Celeron CPU which is Intel's "Consumer low
end" processor. And architecturally, it certainly looks promising.
Being Socket 370
compatible, based on a 0.18 micron fabrication process and having double the
on die L2 as the Celeron, the "Joshua" so far looks to be a great alternative on
the budget PC market.
But before our lives move on to
"Joshua" I just thought I would finish with a review of the last MII CPU made.
The Cyrix MII/433. As we all know, Cyrix (before being bought by VIA) CPUs were
built to compete with Intel's Pentium (now Pentium Classic) CPUs starting with
the 6x86 line of chips. Being plagued with problems such as very low floating
point performance, earlier Cyrix CPUs were targeted toward the business end user
as opposed to the hardcore gamers of that time.
much anticipated 6x86MX was the same 6x86 core with an increase
in L1 cache and an addition of MMX instructions. Soon after that, Cyrix
introduced a CPU with support for a 100MHz FSB the Cyrix MII. Many "CyrixInstead" advocates voiced
their disappointment with the MII as they had hoped for a better floating point unit
and higher clock speeds over the 6x86MX architecture. Throughout the MII line there have been varying
flavours ranging from PR300 - PR433. Strangely enough, the processor has evolved
from a 0.35 micron based chip to a 0.18 micron base with the same MII logo on
the CPU. Supported voltage has evolved as well, from a 2.9V core to a much lower
2.2V core which greatly lessens heat dissipation.
As mentioned earlier, the MII line of CPUs have
undergone some changes throughout the years. Certain specs given below are
specific for the Cyrix MII-433 CPU. No assumption should be made for similar
characteristics for early generation MII's.
- Clock speed of 300MHz with a PR rating of 433MHz
.18-micron fab process
- 2.2V core voltage
- 100MHz FSB officially
- 3.0x Clock multiplier at standard rating
- 64K 4-Way Unified
Write Back cache architecture
- 2 Level TLB (16 Entry L1, 384 Entry L2)
Scratchpad RAM in Unified Cache (L1)
- Compatible with MMX
In order to increase performance
the MII processor contains two caches, the
L1 unified 64 KB 4-way set associative write-back cache and a small high
speed instruction line cache. To provide support for multimedia
operations, the cache can be turned into a scratchpad RAM memory on a line
by line basis.
The cache area set aside as scratchpad memory acts as a private
memory for the CPU and does not participate in cache operations. Within the MII
processor there are two TLBs, the main L1 TLB and the larger L2 TLB. The
direct mapped L1 TLB has 16 entries and the 6-way associative L2 TLB has 384
entries. The floating point unit of the MII is optimized by being able to
process MMX instructions.
The smaller .18-micron process certainly contributes to the
lower voltage requirements and results in a lot less heat dissipation. The most
popular characteristic is the overclockability of .18-micron CPUs. Does the
Cyrix overclock as well as say, a Coppermine? We will soon find
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