Virtual boy
So what about emulation? This involves running a program on the new console that effectively pretends to be the old machine so that it can play classic games. Nintendo, for example, offers its Virtual Console service for the Wii and 3DS which allows owners to download and play classic Super Nintendo, Game Boy and even Sega Mega Drive titles in their original form.
Once again, however, the problem with emulating more recent consoles is technological advance. "It was when the PS3 tried to emulate the PS2 that the increase in technology began to present problems," says developer Byron Atkinson-Jones, whose new game Blast 'Em has just been released. "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."
And timing is not the only issue – the increasing adaptability of the hardware itself is also causing problems. "It's complexity versus schedule," says Hollis. "If your emulated graphics processor is programmable (as PS3 and Xbox 360 are) that creates a huge explosion of possibilities to emulate and test – easily trillions of cases. We are talking large possibility spaces here. No way you are going to be able to emulate all the games, and do the job in a rush. If you had ten years, well maybe.
"The second piece of bad news is performance headroom. To emulate an old system's hardware in software you need a system which is significantly more powerful, I'd say ten times more powerful is a good rule of thumb. 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."