We must not forget the life cycle of a product, so when the speed of sales begins to slow down considerably, one of greater capacities ends up being launched to replace it. In the case of video game consoles, this is called console generations and not always the product of a brand that replaces the previous one is backwards compatible in the sense of being able to use its games.
Traditionally, the solution was to encourage the purchase of new hardware, which was architecturally different from the old one. If the user wanted to continue playing games from the previous system, he had to keep it or pray for some kind of compatibility with the previous generation, either through hardware and, therefore, adding a reduced version in size of the previous console, or through through some emulator, which is less efficient.
With the arrival of the PS5 and Xbox Series generation, we find ourselves in a different way of approaching backwards compatibility. All thanks to the use of AMD hardware for PCs to build the new generation of consoles, a point in common with the previous one.
How does backwards compatibility work on PS5 and Xbox?
If you ask any new user, they will tell you that it is because they are PCs and on that platform there is forward compatibility. However, on consoles things are much more complex and the main reason has to do with the graphics API used. Let’s not forget that on PC there must be an interpreter of the shader code that compiles between the engine, OS and driver for our graphics card model. On consoles like all those of a brand have the same GPU, so the code is precompiled in the game installation files.
This has led to AMD designing RDNA architectures to be backwards compatible with GCNs, but even within that family not all instruction sets are created equal. So in the design of the new chips they have been forced to reimplement the instructions of their predecessors within the ISA of their GPUs as long as it works. Thus, in the backward compatibility of PS5 and Xbox we do not find an RDNA 2-type GPU for PC that has been added to the APU of each of the consoles as is, but rather it has been optimized in terms of its set of records and instructions.
All this is so that they can run the precompiled shaders without problems on more powerful hardware, which allows us to run the games with more graphic power, more resolution and frames per second than in the previous generation.
The importance of the CPU
If we talk about the CPU, it has no more problems and in this case forward compatibility does apply. SONY or Microsoft could even include a more powerful Zen core and only gain performance. As for the backward compatibility of PS5 and Xbox Series, this has been key. Since this allows you to run PS4 and Xbox One code natively and without having to emulate it without emulation and much faster.
How fast? Well, taking into account that we are talking about more than twice the clock speed and a performance per ditto cycle that is double, we are talking about a power four times higher. This translates into the time it takes for the CPU to calculate its share for each frame.
specialized hardware
PS5 and Xbox backward compatibility also requires the re-implementation of accelerators and domain specific units that were in the previous generation and although they have been replaced by much better hardware performing the same function, this is not entirely compatible with the code. ancient.
So, to make sure that everything works without problems, all those pieces of hardware have also been added that, although outdated if they did not exist, would have to be emulated. The latter would cause a performance hit for backwards compatibility. In addition, they are very small pieces, whose implementation is a few cents in the SoC and in general they consume very little. Many of them, by the way, are unknown to us, since they carry out tasks that are not visible to the programmer and are not even documented in the development kits of both consoles.
Despite all efforts there are exceptions, but these are usually due to “illegitimate” uses of the hardware, a phenomenon that occurs when an application is poorly programmed according to the logical rules for developing programs, but still works on the original machine. , but causes them not to do so in the next one.
