Sony quietly adds PS2 emulation to the PS4’s bag of tricks

When Microsoft announced that the Xbox One would gain the ability to play selected Xbox 360 titles, it was big news across the game industry. Sony, in contrast, never said much about its own plans. The company told developers that it would add the feature way back in January 2014 and said very little publicly thereafter. Now, that’s finally changed — Sony has begun re-releasing PS2 titles on the PS4, and it’s clearly running them in emulated mode.

Digital Foundry has the details on this discovery, and a comprehensive slide-by-slide comparison of how each game looks now compared to its original. The PS2 is the most popular console ever built — it was in production from 1999 to 2012 and sold over 157 million units, far exceeding the sales of any other living room console and even narrowly beating Nintendo’s phenomenally successful DS handheld.

While emulation always incurs a performance penalty, the hardware advances between the PS2 era and the modern PS4 allow the new console to render PS2 classics with greater visual fidelity and much-improved results. Digital Foundry notes that the exact particulars depend on the title and that 3D assets scale up much more effectively than 2D art. Because these games are running in emulation, Sony appears to have taken no effort to improve graphics or release an HD version — this is what shipped on the PS2, with only the most minor changes.

DF measured an initial output of 1292×896, followed by the insertion of black bars to bring the final output up to 1080p. The total number of pixels is roughly 4x the original output, and games maintain a smooth 60 FPS throughout. This makes a number of titles control more smoothly, though the fact that these are straight emulated titles means that on-screen controls are still given in terms of the PS2 controller, not the PS4.

So far, Sony has only released a handful of PS2-era Star Wars titles, no doubt to capitalize on the imminent release of The Force Awakens. The company has confirmed, however, that it plans to release more games in the not-too-distant future.

Why emulate the PS2 over the PS3?

If I felt like taking a cheap shot, I’d congratulate Sony for finally finding a way to ship 1080p content on the PS4 at 60 FPS. There’s an actual question behind the snark, however — why is Sony reaching back to the old PS2 catalog with no mention of the newer PS3?

The answer, I suspect, lies in the specific hardware built into Sony’s last-generation console. Both the XBox One and PS4 use AMD’s low-power Jaguar processor, and while that chip was generally faster than the Atom processors it debuted against, it’s nothing like the CPUs that the Xbox 360 and PS3 used.

I admit, I’m actually surprised that MS managed a backwards compatibility mode for Xbox 360 games, though the fact that only certain titles will be supported says something about the strategy. It’s entirely possible that games that were most optimized for the Xbox’s Xenon processor will be the hardest to convert.

Cell, however… Cell is simply a different story altogether. The Xbox 360 contains three cores that are nearly identical to Cell’s PPE (Power Processing Element), which is a general-purpose microprocessor core. Cell also contained seven synergistic processing elements, or SPEs. These SPEs were used for multi-threading, and each had its own dedicated 256KB of embedded SRAM. The chip was designed for extremely high bandwidth and relatively high latency, and timing was absolutely critical.

In other words: Cell was a high-latency, extremely high bandwidth architecture that depended on careful timing and very particular timing in order to hit top performance. Jaguar might be able to emulate a PPE, since Microsoft has obviously gotten it working, but the SPE elements were unlike anything previously shipped in a system. I’m not saying Sony can’t emulate the PS3 on the PS4, but I also think it’s telling that their gaming efforts like the PlayStation Now platform relies on custom PS3 hardware rather than a high-end conventional x86 solution for emulation.

There’s no word yet on which titles Sony intends to bring over from the PS2 if these Star Wars games take off — what favorites would you like to see debut?