Sega: The iPhone is as Powerful as Dreamcast

by Eric March on July 20, 2008 at 11:59 am

Sega of American president Simon Jeffery was, as you might expect, present at E308, and thankfully he had time to sit down and be interviewed by Kotaku to talk about the company and its current and future plans.

Bolstered by the roaring success of Super Monkey Ball and an adoration for the platform, Simon stated that they already have “quite a few” games in development for the iPhone, “…and some very cool stuff.” He would not admit to a Sonic game in the works when asked point blank, but the intimation was there quite strongly. He did however say that they are absolutely be looking back at their Dreamcast lineup for material.

Which brings us to the interesting statement he made. “You’re playing dreamcast-quality games on this tiny little device,” he said, adding when it was brought up that the iPhone’s processing power was comparable to the Dreamcast, “It’s like that, yeah.” I admit, I was a little baffled by this statement, but once I took a look at the tech specs of each device I realized, that’s probably not too far from the truth, though perhaps a tad hyperbolic.

Witness the main CPU, for example. The Dreamcast used a 32-bit Hitachi SuperH SH-4 RISC CPU (specs) with an integrated 128-bit floating point unit (FPU, the thing that does all the hard math) running at 200MHz and pushing 360 million instructions per second (MIPS) and 1.4 gigaflops (that’s 1.4 billion floating point operations per second). The iPhone uses a 32-bit ARM 1176 RISC CPU (specs) that runs natively at 620MHz, but is underclocked to 412MHz. Faster, yes, but there’s no FPU, so the main portion of the CPU has to do the math itself. This lack of an FPU on the iPhone’s CPU means significant degradation in the processor’s ability to handle math-intensive operations like physics calculations.

The graphics processor, or GPU, is where the two are far more similar. The Dreamcast uses the Imagination Technologies PowerVR series 2 GPU running at 100MHz. The chip featured all the latest technologies of the time — perspective-correct hardware texture mapping (helps correct texture distortion), transparency, 32-bit Z-buffering, gouraud shading, coloured light sourcing, MIP mapping, bump mapping, point, trilinear and anisotropic filtering, full scene antialiasing with supersampling, volumetric fog, light and shadow, et cetera. The iPhone uses the PowerVR MBX, which was effectively an enhanced, low-power successor to its KYRO 3 line, but adds capabilities such as curved surfaces, DOT3 lighting (per-pixel lighting), environment mapping (reflections of the game world on shiny surfaces), multitexturing (texture layers), displacement mapping (how imagery gets distorted when viewed through transparent, distorted surfaces like mottled glass, or reflected off of turbulent water), light bloom (how light from bright sources seems to seep around the edges of objects) and more.

Another issue here is bus bandwidth.  The bus is like a highway along which data travels from one component of the system to another.  Like a real highway, the wider it is, the more traffic can move along it at once, side-by-side, so the more data can get from one place to the other in a given time frame.  The Dreamcast utilized a 64-bit bus, which was pretty fat for the day and was rivaled only by its predecessors, the Nintendo 64 and the Atari Jaguar.  That means that 8 bytes can travel along the bus at once, so the processor could concievably send 8 instructions, or 4 instructions with 4 one-byte parameters, to the GPU in one CPU cycle, for example, and the GPU could send just as much data back to the CPU in one CPU cycle.  The iPhone on the other hand runs on a 32-bit bus — half the width, so it can only send a maximum of 4 bytes per CPU cycle.  This again significantly reduces the amount of data the device can process at once.

Now, these are just the primary areas where the two can be most favourably compared. You can also add that the iPhone has more main memory (128mb with 112mb available to the user) and a lower screen resolution, which means less to render and therefore more power available to place 3D objects on the screen and/or add special effects. This is certainly true, but it comes back to the iPhone’s lack of a powerful FPU and its narrower bus, because this is where the Dreamcast shoots out ahead in terms of raw 3D processing power. The ability to handle complex maths and be able to transfer large quantities of data across the bus can’t be underestimated when we’re talking about 3D applications. Math is the core of 3D processing, and distributing the graphics that make up 3D scenery requiers a fat bus. The better a processor is at it, and the wider its bus, the faster and more complex the 3D scenes it can build, and this is where the iPhone falls behind.

Oh, don’t get me wrong — the iPhone is still very capable of building wonderful 3D imagery, but a Dreamcast it is not. Not quite, anyway — its higher specs in some areas go some distance towards mitigating its shortcomings, but not far enough.  Still, it gets close, and that’s no small achievement for such a small handheld.

At any rate, you can watch the interview at the Kotaku link below for all the tasty Sega plans.

(via Kotaku)

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Posted in Gaming Related, In The Works, Product Comparison, iPhone 3G, iPhone Related