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I think it's kind of strange and interesting how the GPU industry is turning PC performance metrics on their head. My new nvidia GTX 650 Ti will bring my computer's processing capacity to somewhere around 2 teraflops. With 1.8 tf of that residing on the GPU alone. Computers of any kind did not reach half of that capacity until 1996. I find that I never get tired of reveling in the idea that my ordinary middle-of-the-road gaming PC is computationally equivalent to a machine for which an entire research department or university would have paid millions of dollars as recently as within my lifetime.

I'm also struck, however, by the surprising asymmetry. There are 768 parallel execution units on this GPU. That is, it has hardware support to perform seven hundred sixty eight simultaneous operations at any given time. It's like a supercomputing cluster on a PCI card. In some ways, I wonder if it isn't the PC which is becoming a peripheral to the video card. I think there will come a time when the PC is relegated to little more than the role of IO backplane, while all of the interesting things happen elsewhere.

To answer why this is, I think we have to consider the burden imposed on x86 architecture by the desire for backward compatibility. As far as I know, it wasn't until the adoption of the amd64 architecture that the PC began to discard legacy features, and even then, this is only in 64-bit "long mode". This means that, in addition to all of the advanced hyper-modern features available on an amd64, there is still all of the supporting circuitry needed to run applications from 1978. Try booting to DOS sometime. It works perfectly. I suspect that CP/M would be no different.

I don't understand why this is. Can't Intel and AMD sell special legacy kits for people who want to run ancient software? Why not just emulate old computers entirely in software? There is absolutely no shortage of processing power to do that, plus there are substantial benefits to virtualization, like snapshotting, as well as the extension of the modern OS's capabilties into the emulated environment.

I think that, at some point, Intel and AMD should simply start over from scratch and design a chip around a modern instruction set. With the recent progress on virtualization technology, I tend to hope that this is the direction in which they are headed already. Even as things are, if I needed to run some sort of x86-based PLC written in QBASIC, I would have no problem emulating several dozen such machines entirely in software. So what is the point of hamstringing the transistorspace with three decades' worth of backward compatibility? Because a PC CPU has, not some, but ALL of the features that were ever implemented over the course of my entire lifetime. 8086, 286, 386, 486, and on, and on, and on. All of those features, many of which are non-features to me, as well as most users, take up space and waste energy.

The GPU, on the other hand, is not burdened by any such issues, and can be designed entirely for raw performance. So, I think that if the results which GPU designers are achieving are any indication, then it means that we're designing CPUs wrong.