PowerVR MBX in iPhone

Discussion in 'Mobile Graphics Architectures and IP' started by Rob Evans, Jul 4, 2007.

  1. Ailuros

    Ailuros Epsilon plus three
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    What's the iPhone's MBXLite clocked at? Even if they're operating at the same frequency, the comparison would be purely on a GPU vs. GPU basis and I'm not so sure that the MBX Lite would lose after all, since it's 2 generations apart from the DC chip (if memory serves well) and there have been quite a few advancements even on "simple" tiling algorithms since then. Fetch the SoC specs of that iPhone and compare to that: http://www.firingsquad.com/hardware/dreamcasthw/page2.asp
     
  2. MoHonRi

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    Edit -- nm, it appears that the info around the net says that the bus speed got bumped up to 103 Mhz. Which is not necessarily the clock speed of the MBX Lite.

    The only info I got on the MBX lite clock speed while googleing was about an SDK a long time ago 2004 that said the max speed for it was ~50 Mhz and at that speed and with the SDK release it could do ~500,000 Polys a second. Of course that was in 2004.....


    http://www.iphoneatlas.com/2007/12/03/112-update-boosts-iphones-clock-speed/
     
  3. Lazy8s

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    The polygon performance of the MBX Lite should approach around one million per second, so it's not up to Dreamcast levels but well beyond N64 and DS.

    [​IMG]
    (a scaling earth benchmark running on the Axim and featured at Loewe's Deferred Power -- http://www.mitrax.de/ )
     
  4. Ailuros

    Ailuros Epsilon plus three
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    I've seen Loewe's demo on an Axim in realtime when he visited me ;) The question still remains what the iPhone MBX Lite is clocked at. I don't recall the x50 MBX Lite frequency but if memory serves well it was either around 75MHz or below. Manufacturing processes have advanced since then and frequencies are higher nowadays; I'm not saying it is, I'm merely asking if you have any info on the final frequency of that iPhone thingy.

    If you still should have the older MBX whitepapers in your hands, compare it to the newest one on their homesite.

     
  5. Lazy8s

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    Interesting; I hadn't noticed that latest performance scale being quoted for the MBX family.

    While I don't know for certain what the clock speed of the iPhone's graphics core is, I've been suspecting 103 MHz, that of the system bus.
     
  6. Ailuros

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    Ask Loewe he most certainly knows what the MBXLite in his Axim is clocked at; if it should be anywhere in the 50MHz region and the iPhone contains something in the =/>100MHz region there's quite a difference after all. How that measures against a Dreamcast I'd still have no idea, but I wouldn't be surprised if it would at least with the right frequency come damn close to it.

    If we'd be talking about a MBX+VGP it would be easy to say that it would beat a DC hands down.
     
  7. Simon F

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    IIRC, an MBX should, in general, be quite a bit faster than a CLX at the same clock rate. The addition of the VGP then offloads a lot of work from the host CPU which makes the whole system faster.
     
  8. darkblu

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    interesting.. didn't the CLX do one pixel per clock?
     
  9. Simon F

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    The texturing and shading processor did one pixel per clock as does MBX - the latter is more efficient when AA is being used.

    The HSR front ends of both chips run at higher pixel/clock rates but, IIRC, MBX has some additional efficiency improvements.
     
  10. Lazy8s

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    Doesn't the CLX2 have a higher effective peak opaque fill -- maybe 32 Z comaparators compared to 8 or less -- than MBX?
     
  11. Simon F

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    Yes.... but MBX adds one important facility which, in practice, makes up for this.... but I doubt I should say any more.
     
  12. Ailuros

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    Again consider that the CLX2 and MBX are two whole technology generations apart. Of how many pixels/clock is the CLX2 capable of anyway?

    If memory serves well MBX didn't inherit maybe one aspect of the Series4 generation, which probably makes it's Multisampling on one axis capability rather a moot point.
     
  13. Iron Tiger

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    Clock for clock, the iPhone's MBX Lite should outperform the Axim's since the iPhone's screen is at a lower resolution. Most every accelerated demo or game I ran on my X50v was at 640x480. Also consider that the Dreamcast ran at that res.

    Process shrinkage may not have led to an increase in clocks as the iPhone has MUCH better battery life and stays cool in operation (only heating up when wireless components are active).
     
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