Intel's 90nm Pentium M 755: Dothan Investigated
by Anand Lal Shimpi on July 21, 2004 12:05 AM EST- Posted in
- CPUs
Sixteen months ago, Intel released a confusing little thing called Centrino; it wasn't a new processor or chipset, but rather a "technology". Intel pumped billions into the marketing of this technology and even to this day, we still see the same "What is Centrino?" question. But unlike most multi-billion dollar marketing campaigns, Centrino wasn't a hip name masking uninteresting technology; instead, Centrino encompassed one of the most impressive microprocessor architectures to ever come out of Intel: Banias.
We had all heard about Banias, which was officially named the Pentium M, for almost two years, but most shrugged it off as a rebranded Pentium III. With the Pentium 4's power requirements climbing, it was all too easy to believe that Intel would just go back to a much cooler running architecture for the future of their mobile processors. Pentium M became known as a Pentium III with the Pentium 4's Front Side Bus long before it ever shipped, before the first benchmarks were ever run. But as we just finished mentioning, this processor was far from rehashed technology.
Last year, we took an in-depth look at the Pentium M and came away from the experience extremely pleased. Our sentiments were echoed by manufacturers and end users alike, with the Pentium M and Centrino notebooks that use the processor selling extremely well and truly enabling high performance, long battery life, thin and light notebooks. Offerings like IBM's Thinkpad X series grew extremely popular among business users while more stylistic options, like the Sony VAIO X series, brought a new meaning to portable, with Pentium M designs weighing less than 1.8lbs. What Pentium M brought Intel was the portability and form factor advantages of Transmeta, with the performance that Intel customers were used to.
To put it bluntly, Intel's Pentium M was an instant success and well deserving of the success at that. But in our long running history at AnandTech, we've never been quite satisfied with one successful product - we want to see improvements, perfection of the perfect, if you will. And thus, it was no surprise that we were quite eager to take a look at the follow-up to Intel's 0.13-micron Pentium M, code-named Dothan.
We first heard about Dothan before Banias ever hit the streets as Pentium M. If you'll remember from our original article on the Pentium M, Banias only missed its target completion date by a matter of days. One by-product of on-time execution was that a number of architectural tweaks that the design team wanted to get into Banias had to be left out, a sacrifice made to preserve on-time execution. As soon as the Banias design was complete, those final architectural tweaks and enhancements that didn't make it into the first Pentium M incarnation were at the top of the list for its successor. As a result, Dothan is best viewed as a more polished evolution of Banias, with higher clocks and more cache made possible by Intel's 90nm process.
But unlike Banias, Dothan wasn't the perfect student on time to its launch; instead, Dothan was released after months of delays. Intel has already publicly released the reason for Dothan's delay. There was apparently an analog design issue with Dothan; more specifically, a PLL was too jittery. Dothan was actually in the hands of OEMs back in January, but the yields were extremely low, thanks to the jittery PLL issue. The solution to the problem required another spin of the silicon, which takes a long time (even longer at 90nm) and resulted in Dothan's lengthy delay.
Being an evolutionary, rather than revolutionary part, Dothan isn't nearly as exciting to talk about as Banias was, but as you'll soon see, that doesn't take away from its worthiness of carrying the Pentium M name.
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phtbddh - Wednesday, July 21, 2004 - link
What is the battery life of a Dothan compared to a Banias? I know the Dothan is suppose to be better, but can we see some numbers?tfranzese - Wednesday, July 21, 2004 - link
Not quite SKiller, a large part of the P4's dominance in media encoding is the high core frequency attributed to such a long pipeline.SKiller - Wednesday, July 21, 2004 - link
I think the assertion that.."With Intel's vision for the future being centered on media encoding and content creation, the Pentium M is the last thing that Intel would want to build their future desktop CPUs around."
..may not be correct as by your own admission:
"Partially constrained by its 400MHz FSB and single channel memory interface, the Pentium M is not the successor to the Pentium 4 that many will make it out to be."
So all Intel would have to do is up the FSB on a desktop version to improve media encoding and content creation performance and be competitive with P4.
mkruer - Wednesday, July 21, 2004 - link
you know i wonder just how much of the preformance is gained from the 2MB of L2 cache. If I recall from Aceshardware the 2MB is the sweetspot For mico op code, any more, and there is a preformance hit in either direction, Also on a side note. The 90nm Athlon 64 show a ~5% improvement across the board.dvinnen - Wednesday, July 21, 2004 - link
Yea, I was wondering the same thing. Why not just use a mobile A64 system with a mobile 9600. Acer and emachines make systems with them.alexruiz - Wednesday, July 21, 2004 - link
Another one: Was that difficult to get an eMachines M68xx for the review? Mobile against mobile.alexruiz - Wednesday, July 21, 2004 - link
Anand made a huge mistake in the Athlon 64 CPU selection. The mobile [b]A64 3000+ is clocked at 1.8 GHz with a 1MB L2 cache[/b]. He used a desktop 2.0 GHz with 512 K. This will affect the outcome, specially because clock speed matters more cache.I knew Dotham was going to give a very good fight, but I didn't expect it to win any gaming application ot Business Winstone. As reference, my M6805 A64 3000+ scores 22.2 and 27.8 in the BW and CCMW tests (7K60 hard drive, so not the same setup)
A very good review, but we can do better. I still want to see video encoding tests run with a commercial application, preferably 3 (Ulead Video Studio 8, Roxio Videowave 7, Pinnacle 9) and 2 alternative programs for DivX encoding (DVD2AVI and virtualdubmod are suggested. We have seen enough XMPEG from other sites)
Run some photoedition benchmarks not only with Adobe, but also with Corel Photopaint 11 or Roxio Photosuite.
AutoCAD is also expected to give an idea of what be attained. SolidWorks or UG would be fantastic, but those 2 are more of a wish.
How about more scientific or technical programs? Electrical simulators (PSpice for example), FEA (Nastran), MathCAd, Maple, etc.
More games were expected to be run. Howe about chess programs? How about OSmark, the succesor of COSBI by Van Smith?
I stressed the use of 2 or more applications that do the same to highlight the fact that software optimization matters a lot and that some myth about a CPU being "the best for that activity" are only myths.
All in all, Dotham is a potent rival that uncovers some weaknesses in the K7/K8 architecture that were noticeable against the P6 (Pentium II/III) but forgotten against the P7 (Pentium 4): [b]L2 cache performance[/b] and integer performance.
Regarding battery life keep in mind that the CPU is not the biggest spender in a laptop, the screen is. The K8T800, the most popular chipset for AMF64 laptops is a desktop part, and is quite voracious. Keep those factor when battery life is evaluated.
I foresee that SOI will give AMD the edge in battery life once they implement power saving caches, the biggest energy conservation feature in the P-M.
Comments are welcome
Alex
dacaw - Wednesday, July 21, 2004 - link
Well Dothan looks very much like a copy of a 32-bit AthlonXP to me.Comparing it to an Athlon64 makes no sense. Dothan is not 64-bit.
I bought an AthlonXP Barton mobile 2600 for $99 and it runs barely warm under PowerNow. What could you buy for the price of a Dothan? Maybe 5 top-of-the-line Athlon XPs?
Let's compare apples to apples and have a review of top-of-the line Dothan to top-of-the-line AthlonXP.
Oh, and drop those fake synthetic benchmarks. What point are they if they simply "favor" Intel processors (your comment in the review).
Come on Anand, lets have a review that really means something. Please!
Jeff7181 - Wednesday, July 21, 2004 - link
Can't wait to see battery life tests.mino - Wednesday, July 21, 2004 - link
Nice review, however it is a shame you didn't include Celeron 2.4 (which could be find in many SLOW notebooks) and also AXP-M 2600+ would be nice. -> this way it would be a complete notebook market review. - The best one.I'll love to see bench results of Cely and XP added (by using same desktop platform as you did in case of P4)
mino