Why isn’t PS4 backwards compatible? Three reasons PS3 games won’t play on PS4

Heat, processing issues and lack of power are the main culprits behind PS4‘s lack of backwards compatibility. PS3 games might appear on PlayStation 4 via Gaikai in the future but there are several strong reasons why you’ll never play old games straight off the disc.

Why isn’t PS4 backwards compatible?

Speaking to The Guardian former Rare dev Martin Hollis explains the problems behind backwards compatibility. Hollis states that the two usual options would be either to build PS3 chips into PS4 or to emulate it via sofware. Those approaches worked in the past but are now impracticable. Here are the three main reasons:

1 Heat

While cost is now a big issue in adding old chipsets to new consoles (how much would a PS4 cost with a PS3 built in?) the biggest problem is heat. “With the high frequency clock rates (GHz), designing your board to incorporate the entire old machine is not easy or cheap, and worse, it will emit just as much heat as the old system did on its own”, says Hollis. “Heat is a big factor with modern system designs and you do not want to add 100 watts to your output, and another jet turbine style fan.”

2 Software emulation

Basically early hardware could be backwards compatible because the chips and tech involved were simpler. With PS3′s six core Cell that’s not so easy – software emulation has to recreate the effect of several processes all happening at once through timing alone. Hollis explains: “Like the PS1, the PS2 had a single processor but the graphics system was a lot more complex, allowing for parallel processing, which meant it could run more than one bit of code at a time. You can emulate this on the more modern processors but you have to get the timing between the true hardware-based parallel processing and the software emulated version exactly right. And that timing would also have to take into account the differences between the territory versions, i.e. a game running on PAL or NTSC. Along with other factors that might be enough to break a game.”

3 Performance headroom

One last problem is that the PS4 would need to be significantly more powerful than PS3 to run a PS3 game. And while PlayStation 4 is powerful it’s not the “ten times more powerful” Hollis estimates would be required. “To emulate an old system’s hardware in software you need a system which is significantly more powerful. This current generation is simply not that much more powerful than the last, especially in terms of general purpose compute. Moore’s law is basically over for CPUs, and has been for around five years. That means new machines do not have the power to emulate last generation in software.”

Thanks to The Guardian.