Inside Snapdragon is a Scorpion

Several years ago Qualcomm assembled an architecture team in the Research Triangle Park in NC, coincidentally around 30 minutes from where I live. One of their tasks was to design a high performance CPU core around the ARMv7 instruction set. They called it Scorpion.

While the Scorpion core is normally referred to as a Cortex A8, Qualcomm views it as more of a Cortex A9 competitor. The truth, as always, lies somewhere in between. Like the Cortex A8, Scorpion is a dual-issue in-order microprocessor architecture. As I mentioned in my iPhone 3GS article, you can think of it as a modern day Pentium processor (but not an Atom).

Qualcomm claims the ability to do some things out of order, but by and large the pipeline is in order which ultimately keeps it out of the A9 classification.

Qualcomm hasn't shared much about the base architecture other than to say that it's definitely not based on the Cortex A8. It might have a deeper pipeline than the Cortex A8 to help it reach higher clock speeds. Unlike the ~600MHz target the A8 will hit at 65nm, Qualcomm's Scorpion will run at 1GHz at 65nm.

Scorpion also implements the NEON extensions to the ARMv7 ISA, although Qualcomm's implementation is a higher throughput version of what the Cortex A8 offers. It's my understanding that NEON isn't very widespread in usage today, so I'm not sure that Qualcomm's advantage here matters just yet.

Cache sizes are unknown but I'd expect that they're competitive with what we've seen from competing Cortex A8 implementations. Ultimately everyone is bound by die size and power consumption at 65nm.

Qualcomm integrates the Scorpion core in its Snapdragon SoC. The version of Snapdragon in the Nexus One is the QSD8250. This SoC includes a 1GHz Scorpion core and an integrated 3G modem. The QSD8650 will be used in the Verizon version with support for EVDO and CDMA 2000.

Qualcomm's integrated modem is a very different approach from what we've seen from companies like NVIDIA, Apple/Samsung and TI. Those companies rely on an external modem solution to reduce time to market. Qualcomm's response is to instead offer an SoC that integrates support for all major wireless standards. The QSD8250 used in AT&T's supports GSM, GPRS, EDGE and HPSA networks.  The QSD8650 supports CDMA2000 1X, 1xEV-DO Rel 0/A/B, GSM, GPRS, EDGE and HSPA wireless networks.

When I spoke with Qualcomm one message it stressed was how calculated the timing of Snapdragon was. It's not by accident that all of the major Android phones being announced today use Snapdragon, it's because of very careful timing and planning that Qualcom was able to hit this bulge in the market. Most SoC makers would cite time to market as a reason for not integrating a modem into an application processor, it's clear that Qualcomm faced that challenge and took timing very seriously with Snap Dragon.

The CPU side of the Snapdragon SoC is fast. Faster than what's in the iPhone 3GS, Palm Pre and Motrola Droid. Unfortunately there are other issues. Qualcomm scaled up processing speed but didn't increase memory bandwidth. The Snapdragon still has a 32-bit LPDDR1 interface, giving it the same memory bandwidth as its competitors despite boasting a much higher clock speed.

The even bigger problem with Snapdragon is its use of the Adreno 200, a dated and slow GPU Qualcomm acquired from ATI a couple of years ago. Luckily for Qualcomm, intensive 3D gaming hasn't really taken off on smartphones just yet but here Snapdragon is at a disadvantage to the Samsung and TI SoCs that use Imagination Tech's PowerVR SGX.

So the Nexus One has better CPU performance, identical memory bandwidth and worse GPU performance compared to the iPhone 3GS. Nothing is ever easy in this world.

Later this year Qualcomm will introduce its 45nm Snapdragon SoCs. These will range from being simple clock bumps of the 8650 in the Nexus One with LPDDR2 support, to full fledged dual-core versions with a much higher performance 3D core. Qualcomm also confirmed its intentions to move to an out-of-order architecture at some point in the future. I'd expect to hear more about that next year.

Enter the Snapdragon The Display, My Love, the Display


View All Comments

  • KaarlisK - Saturday, April 03, 2010 - link

    ´´The graph below shows the rough costs of simply keeping up with fab technology every two years:´´
    Can´t seem to find it.
  • deputc26 - Saturday, April 03, 2010 - link

    Thanks Anand, Great Review! Reply
  • windywoo - Sunday, April 04, 2010 - link

    Taken out of context like that, the quote sounds like it is describing a graph of smartphone prices, laptops, e-readers :) Fab tech. Reply
  • Nihility - Saturday, April 03, 2010 - link

    I just know that after experiencing any responsiveness issues, that within a few months I'll get really frustrated with the device.
    I still have an iPhone 2G and I hate it. Takes forever to launch apps, browsing the web is a miserable experience and the battery life sucks. I'm definitely in the market for a better phone but I think I'll just wait for something smoother.

    One of my main gripes is that my navigation app for the iPhone takes ages to load and if I get a call mid-work I'll have to restart it. Hate that.

    Like Anand said, on paper the N1 is perferct but I'll let them smooth out the rough parts before I get one.
  • Exelius - Saturday, April 03, 2010 - link

    I had the same complaint of my iPhone 3G. I bought a 3GS the day it came out and it is a huge improvement over both the 2G and 3G in responsiveness. My girlfriend has a regular 3G and much prefers using my 3GS over her own phone when browsing the web or using the Maps application.

    If responsiveness is a problem on the iPhone platform, get a 3GS before ditching the iPhone completely. The hardware on the 3GS is roughly equivalent to the Nexus One.
  • Nihility - Saturday, April 03, 2010 - link

    No way. Fool me once, shame on you. Fool me twice...
    No more iPhones for me.

    My main concern was all my apps, but most of them are available for the Android so there's nothing holding me back. I'll be glad to get rid of iTunes.
  • solipsism - Saturday, April 03, 2010 - link

    You're comparing a phone from 2007 with an ARMv6 @400MHz w/ 128MB RAM and discounting the model that came two years later with ARMv7 @ 600MHz w/ 256MB RAM. Makes perfect sense¡ Reply
  • KaarlisK - Saturday, April 03, 2010 - link

    I love both the attention to detail and depth you have :)

    And I have to say that Android, not WinMo7, is the replacement for Windows Mobile 6.5 in my eyes. WinMo7 just isn´t WinMo :D
  • LuxZg - Sunday, April 04, 2010 - link

    I agree, great review, I think I've never read anything that long about a phone :)
    And I agree with Android being a true Windows Mobile successor.. I don't have money for stuff like this, but if I did - I'd want all the freedom of my PC on my mobile as well. In that regard, Android seems to be the only option at the moment.

    There is one thing that will clearly make lives of some people miserable.. Data rates in some countries are horrible, and smartphones all rely on mobile data connection heavily, but Nexus One is a data-hog champion by the looks of it. Hopefully, by the time I'll be able to afford phones like this one, this will be solved :)
  • macs - Saturday, April 03, 2010 - link

    Thank you Anand, the review is great and as an owner of the Nexus One I agree with your thoughts.

    Android world is so wide that it's really hard to have a complete review and I think what is really missing here is something about the community around Android, XDA forum, CyanogenMOD , USB Tethering, WIFI Tethering,...

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