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The
CPU Guide
AMD
K5
The AMD K5
has been coming slowly, but now it's there and getting better and
better. By now, you can get it from a PR 75 up to a PR 166. It's FPU
is still slower than the FPU of the Pentium, but it's better than
the FPU of the 6x86. It also will soon be released as a split
voltage version, which will reduce heat problems of this CPU as
well.
Here a table to
show the weird CPU speed/bus speed/multiplier relations of the K5
CPUs:
Processor
Performance |
Clock
Speed
(MHz) |
Bus
Speed
(MHz) |
PCI
Bus Speed
(MHz) |
Multiplier |
K5
PR75 |
75 |
50 |
25 |
1.5 |
K5
PR 90 |
90 |
60 |
30 |
1.5 |
K5
PR 100 |
100 |
66 |
33 |
1.5 |
K5
PR 120 |
90 |
60 |
30 |
1.5 |
K5
PR133 |
100 |
66 |
33 |
1.5 |
K5
PR 166 |
116.66 |
66 |
33 |
1.75 |
As you can see, the
PR120 runs at the same speed as the PR90, the PR100 runs at the same
speed as the PR133. These CPUs obviously have got a different die.
The PR120 and PR133 are more advanced than the PR90/100. This
however only touches the integer performance. The FPU performance of
the PR133 is the same as of the PR100.
Due to these
strange multiplier settings, the K5 has got a fixed multiplier,
which cannot be changed from out side via multiplier jumpers. The
PR75 to PR133 will run at 1.5 multiplier regardless what the jumpers
say, the PR166 will also always run at x1.75.
The
IDT WinChip C6 CPU
When IDT announced
the C6 CPU in the first half of 1998 it came as quite a surprise to
most of us. After this first introduction it became pretty quiet
around IDT again and only now this new Socket 7 CPU starts shipping.
Targeted against the Intel Pentium MMX, IDT claimed that the C6 has
got about the same integer performance at the same clock speed as
the Pentium MMX. IDT was also not making any secret of the fact that
the floating point as well as the MMX unit of the C6 will not be as
fast as in the Intel Pentium MMX. The C6 is targeted to the lower
end market, similar to the lower clocked versions of the AMD K6 and
the IBM/Cyrix 6x86MX CPUs. The special trick of IDT is supposed to
be the fact that the chip is fairly small as well as requiring only
little power and IDT is therefore pretty confident of raising the
clock speed to up to 400 MHz soon as well as using the C6 in
notebooks where low power consumption is crucial.
The architecture of
the C6 is much less sophisticated than the architecture of its
competitors AMD K6 and IBM/Cyrix 6x86MX. No 'register renaming' or
'out of order execution' is used here for reaching Pentium MMX
performance but simply a large L1 cache in cooperation with a pretty
classic but straight forward microprocessor design.
At the Computex in
June IDT only showed a few systems with C6 CPUs running at 150 or
180 MHz. I also had one 150 MHz engineering sample a few months ago
which couldn't really impress me a lot. Now IDT shipped a whole
system to me with a 200 MHz C6 so that I could test if this new
Socket 7 CPU is living up to its claims. I compared the C6 200 to
the Intel Pentium MMX 200, the AMD K6 166 and 200 and the IBM/Cyrix
6x86MX PR2 166 (running at 133 MHz) and PR2 200 (166 MHz). The price
of the C6 200 lies pretty much somewhere in between these CPUs, with
the Intel Pentium MMX as the most expensive, the IBM/Cyrix 6x86 PR2
166 as the cheapest.
The IDT WinChip C6
CPU is certainly no particularly great performer, but that was never
claimed by IDT either. It is a 'low trouble' CPU with a decent
integer performance under Windows 95 that might have some impact at
the low end sector of IBM's and Cyrix's 6x86MX market. I personally
like this CPU and would prefer it to the 6x86MX PR2 166, because
it's so much easier to handle, however as long as the 6x86MX is
cheaper, I wouldn't see a sensible reason for spending more money on
the C6. Although my expectations were extremely low, the C6 shows
that it can beat at least the slowest 6x86MX or offer pretty much
the same performance.The C6 will be sold for $135 (200 MHz), $90
(180 MHz). The $135 for the 200 MHz version are pretty much the same
what the PR2 200 rated K6 and 6x86MX CPU will cost from beginning of
November. Both CPUs are faster than the C6 200, so that IDT will
have to lower prices pretty soon if they want to sell the chip.
What I would like
to see in the near future is a real low power version of
the C6, which is running at 2.8V or even less. Then I hope that IDT
will be able to crank up the clock rate yields, which could result
in quite a market share, probably taking over customers of IBM and
Cyrix. I think that the biggest future of the C6 will be in the
notebook market in case they can reduce the voltage to about 2V.
This and a clock rate of 400 MHz will even give Intel and its
upcoming notebook version of the Pentium II quite a little bit to
think about.
The road map
doesn't look too bad regarding the above said. IDT is planning a 225
(3x75) MHz and a 240 (4x60) MHz version for this November and next
year there will be a WinChip C6+ with improved FPU performance (as
fast as Pentium MMX) and much improved MMX performance (faster than
Pentium MMX) as well as extended x86 instructions that shall improve
3D performance up to threefold. These new instructions will be
distributed within Microsoft's next Direct3D. The WinChip C6+ will
use a 1/4 micron die and run at only 2.5 V.
For late '98 we can
expect a 300 MHz C6+ as well as a new version with on-chip 256kB L2
cache.
The
Cyrix 6x86 CPU
The Cyrix 6x86 or
M1, as it was called before, is a strong contender to the Intel
Pentium and is able to outclass the Pentium in quite a few respects.
This CPU might also be able to push technology forward more than the
current Pentium CPUs, because since the 6x86 P200+ was released, a
new bus speed of 75 MHz turned up at the horizon to replace
the old maximum of 66 MHz of Intel CPUs. This will require new
memory technology as well as new chipsets and therefore new
motherboards.
This however is
also the downside of the new 6x86 P200+, because you can't run this
chip in a Triton FX or HX board for they don't support a bus speed
of 75 MHz. Only to remind you - the 6x86 P200+ runs at a clock speed
of 150 MHz, which is a multiplying of the 75 MHz bus speed with 2.
Would you run this CPU with a bus speed of only 50 MHz and a
multiplier of 3, you would loose all the speed advantages due to
this pathetic slow bus speed.
Technical
Specifications of the 6x86
Processor
Performance |
Clock
Speed
(MHz) |
Bus
Speed
(MHz) |
PCI
Bus Speed
(MHz) |
Multiplier |
Special |
6x86-P200+ |
150 |
75 |
37.5
or 33 |
2 |
needs
special motherboard and chipset to support
75 MHz bus speed ! |
6x86-P166+ |
133 |
66 |
33 |
2 |
no |
6x86-P150+ |
120 |
60 |
30 |
2 |
no |
6x86-P133+ |
110 |
55 |
27.5 |
2 |
needs
motherboard that supports 55MHz bus speed |
6x86-P120+ |
100 |
50 |
25 |
2 |
no |
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Clocking
2x, 3x bus-to-core clock multiplier, no 1.5 or 2.5 clock
multiplier! |
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L1
Cache 16-KByte; write-back; 4-way associative; unified
instruction and data; dual-port address |
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Bus
64-bit external data bus; 32-bit address bus |
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Pin/Socket
P54C socket compatible (296-pin PGA) |
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Compatibility
Fully compatible with x86 operating systems and software
including Windows 95, Windows, Windows NT, OS/2, DOS,
Solaris and UNIX |
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Floating
Point Unit 80-bit with 64-bit interface; parallel execution;
uses x87 instruction set; IEEE-754 compatible |
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Voltage
3.3V core with 5V I/O tolerance |
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Power
Management System Management Mode (SMM); hardware suspend;
FPU auto-idle |
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Multiprocessing
Supports SLiC/MP(TM) and OpenPIC(TM) interrupt architecture |
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Burst
Order 1-plus-4 or linear burst |
Problems with
the 6x86 and the solution
Problem |
Solution(s) |
The
6x86 needs lots of power, more than a Intel Pentium. This
leads to two different problems.
- The voltage regulator
has to supply much more current, which some regulators
are not up to. The regulators get very hot.
- The 6x86 CPU gets much
hotter than a Pentium, which means that you have to
take special precautions for good cooling of the CPU.
I only can recommend the original Cyrix P200+ heat
sink with fan, which is very good.
There are
so far three different voltage specifications of the
single voltage 6x86.
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Type
C028, which requires 3.52 V |
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Type
C016, which requires 3.3 V |
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'voltage
switching' types, which can work with any of the
above voltages |
It's a
matter of fact, that at a lower voltage the chip needs
less current and produces less heat.
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There
are two solutions from Cyrix to this problem
- 6x86 of the revision
2.7 or higher need considerably less current or power
than the previous versions. If you should want to buy
a single voltage 6x86, you should at least get a
revision 2.7 or higher.
- The 6x86L won't have
this problem at all, since it runs at 2.8 V and needs
under some conditions even less current than a Pentium
of the same P-rating. This is the best 6x86 you can
get. I wouldn't buy any other 6x86 model.
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The
6x86 is very sensitive to reflections on the different
buses. This was leading Microsoft to switch off the write
back L1 cache of the 6x86 completely in Windows NT 4.0.
This results in a serious performance decrease under this
OS for 6x86 users. |
There
are also several different solutions to this problem:
- Cyrix offers a
replacement to all registered NT4 users who are
affected by this 25% performance decrease. Read more
about this on Brian Davis' excellent 6x86 site.
- You also can download
a software patch to enable the L1 cache again. However
this *can* lead to instability under NT4.
- The revisions 2.7 and
higher are not affected by this NT4 problem. You'll
best get one of these or even better a 6x86L in the
first place.
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The
FPU (Floating Point Unit) of the 6x86 is considerably
slower than the FPU of the Pentium. A 6x86 P166+ has a FPU
performance of a Pentium 90 only. This is something most
people noticed in the game Quake. |
Unfortunately
there is no solution to this. Please consider however,
that the FPU is only needed in very few applications like
CAD or other calculating applications. It really depends
on how important Quake is to you. It is expected, that
more future games will use the FPU. Let's hope that the M2
will have a better FPU than the 6x86. |
The
Cyrix 6x86L CPU
The 6x86 CPU was
not a child that came to the world and was making every person, that
had to deal with it, happy straight away. The 6x86 had it's problems
and Cyrix had to fight with a lot of trouble since the 6x86 release.
However this doesn't say that Cyrix wasn't working extremely hard to
survive by fixing one problem after the other. The latest
improvement the 6x86 has received from its creator is the most
pleasing one and eventually now I am happy with the 6x86 as well.
The letter 'L' behind the CPU name is making all the difference to
me and hopefully to all the possible 6x86 buyers as well.
The 'L' stands for
'low voltage' and doesn't say anything else as that the 6x86 now
also has got the 'split voltage' feature known from the newly
released Pentium MMX. Now for the Pentium this isn't making much of
a difference, since the Pentium never had to fight any serious
current or heat problems. For the 6x86 however, this could be the
final liberation from his bad name as 'chip fryer'.
The 6x86L has just
as the Pentium MMX a 2.8 V core and a 3.3 V I/O interface voltage.
Cyrix expects a power reduction of more than 25% of the previous
models, which will keep the CPU much cooler and won't ask for more
current than a Pentium MMX.
This is probably
the solution for all the people who have been scared by the recent
problems with the 6x86. Unfortunately it comes a little bit late,
since everyone is waiting for the M2 and the Pentium MMX 200 is much
faster than a 6x86 P200+ (which is even on a lower level than the
Pentium MMX 166 in most applications). However, who thinks that a
P200+ is still by far fast enough and who doesn't want to spend as
much money as for Intel CPUs, should get a 6x86L and nothing else.
Getting an old 6x86 without the 'L' now is considered to be
completely crazy, unless the old single voltage 6x86 shouldn't be
considerably cheaper than the 6x86L.
The
Intel Pentium Classic
I don't think
there's too much to say about the Pentium, because there's that much
information already being released on the net and in magazines.
However there's one important thing, which doesn't seem to be known
too well. It's the fact that Pentiums of the same clock speed are
not all the same, but can be VERY different, and you should know
that before you get one ! There are now three reasons for that to be
considered:
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Second
class Pentiums, which require a higher voltage or are not
capable of multi processing |
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Intel is
actually releasing different kinds of Pentiums. Some are not
capable of multi processing, others have to have a higher
supply voltage to run correctly. You have to realize, that
Intel is not having a different production line for each
clock speed, but is in real now producing more or less only
one dye. After the chips have been produced, they are
tested, and regarding how they performed in the test, the
clock rates are chosen. Some chips would work correctly on a
special clock rate only with a higher voltage, which means
also getting hotter. Others wouldn't work with multi
processing. To find out which kind of CPU you have or are
offered, you have to have a look on the bottom side of the
chip, where's written something like e.g. SK 106 SSS. These
last three letters can tell you what kind of CPU you have,
and here's the list. It's obvious, that you should
try hard getting a chip, that runs at 3.3 V(Standard)
rather than 3.4 to 3.6 V (VRE), and maybe it makes
you feel better to know that you've got a real
Pentium, that works with multi processing as well, though
you won't be able to use multi processing on a Triton board.
If you should be into overclocking, it's almost inevitable
to get a SSS-chip, because than you still can increase the
voltage on the motherboard to get it running at a higher
clock speed (as long as you cool it well!).
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The
Intel Pentium MMX
The Technical
Advantages of the Pentium MMX over the Pentium Classic
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doubling
of the L1 caches, 16kB data and 16 kB instruction cache |
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data
cache now 4 way set associative - only 2 way set associative
in Pentium classic |
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doubling
of the Write Buffers, now 4 instead of 2 |
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new
branch prediction unit, taken from the Pentium Pro |
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implementation
of a Return Stack, as known from the Cyrix/IBM 6x86 |
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increase
of the U and V Pipelines by one step |
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improvement
of the Parallel Processing Ability of the two pipelines |
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the
MMX instruction set with the ability to pair up two MMX
instructions in one go, hence 2 SIMD instructions can be
processed with 16 byte data in one clock cycle |
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new
split voltage technology, 2.8 V for CPU core, 3.3 V for CPU
I/O interface |
The Intel
Pentium-Pro CPU
The family consists
of processors at 150 Mhz and higher and is easily scalable to up to
four microprocessors in a multiprocessor system and is suitable
specially for servers.
Features
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Available
at 150MHz, 166MHz, 180MHz and 200MHz core speeds |
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Optimized
for 32-bit applications running on advanced 32-bit operating
systems. (16 bit programs runs slower). |
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Single
package includes Pentium® Pro processor CPU, cache and
system bus interface |
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Scalable
up to four processors and 4 GB memory (suitable for
servers) |
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Separate
dedicated external system bus, and dedicated internal
full-speed cache bus |
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8K/8K
separate data and instruction, non-blocking, level one cache |
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Available
with integrated 256 KB, 512 KB or 1 MB non-blocking, level
two cache on package |
Core
Frequency |
L2 Cache
Size |
L1
Instruction/Data
Cache Size |
150 MHz |
256-Kbytes |
8-Kbytes/8-Kbytes |
166 MHz |
512-Kbytes |
8-Kbytes/8-Kbytes |
180 MHz |
256-Kbytes |
8-Kbytes/8-Kbytes |
200 MHz |
512-Kbytes |
8-Kbytes/8-Kbytes |
The Intel
Pentium II (P-II)
It is simply
Pentium Pro + MMX. The Intel Pentium II processors deliver good
performance and are fully compatible with existing software.
The Intel Pentium II processor family includes 233MHz, 266MHz,
300MHz, 333MHz, (FSB Speed 66 MHz) and 350MHz,
400MHz, 450MHz (FSB Speed 100 MHz) versions. The processor
core is packaged in the Single Edge Contact (SEC) cartridge.
Features of P-II:
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Available
in speeds from 233MHz up to 450MHz. |
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Includes
MMX technology. |
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At
450MHz, delivers a 25% performance boost over the 333MHz
Pentium II processor |
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Dual
Independent Bus (DIB) architecture increases bandwidth and
performance over single-bus processors. |
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350MHz,
400 MHz and 450MHz versions improve system
bandwidth and performance by increasing the system bus speed
from 66MHz to 100MHz. The Intel 440BX AGP set enables the
100MHz system bus to increase peak processor data transfers
to the rest of the system by 50%. |
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32K
(16K/16K) non-blocking, level-one cache provides fast access
to heavily used data. |
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512K
unified, non-blocking, level-two cache. |
The Intel
Celeron Processor
The Intel Celeron
processor, is for the Basic PC (sub-$1000) market segment. The
Intel Celeron processor meets the core needs and affordability
requirements common to many new users. Intel Celeron processor
benefits from the same P6 microarchitecture core as the Pentium
II processor. It is same as P-II minus the l2 cache. Intel
was forced to release this as a cost effective soulution because of
the competition it has been facing in CPU market. Currently Celeron
processor is available with 128 KB L2 cache.
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Provides
a base level of functionality to meet the core needs and
affordability requirements common to new home and business
PC users. |
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Based
on the Intel P6 microarchitecture, the same
microarchitecture the Pentium II processor is based on. |
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Utilizes
the Intel P6 microarchitecture’s multi-transaction system
bus at 66MHz. |
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Includes
a 32K (16K/16K) non-blocking, level-one cache that provides
fast access to heavily used data. |
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Available
in the single edge processor package (S.E.P.P.) form factor,
which maintains compatibility with Slot 1. |
AMD ALTHON
(CURRENTLY FASTEST CPU ON EARTH)
Back in end 1998 at
the Microprocessor Forum in San Jose, California, the PC-world
watched and listened in amazement to Dirk Meyer's first presentation
of K7's or now Athlon's architecture. It was quite obvious to
experts as well to most other listeners, including Intel employees,
that this new AMD processor would mark a new era in the processor
world, if AMD could make its promises come true. Now finally, the
waiting is over and we can look at a new processor that is indeed
living up to all the positive expectations that arose at the end of
last year.
Athlon was designed
with the future in mind. The architecture is designed for very high
clock rates and obviously superior to Intel's P6-architecture,
including the Pentium III. If AMD can deliver Athlon and move over
to .18µ-process soon, Athlon will be a continuos threat for Intel,
even beyond Coppermine. And currently Althon beats Intel flagship
chip Pentium-III in almost all spheres.
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