Why PS5 can play PS4 games？

[buklu]

Does it have ps4 emulator？

[Deuxez]

6 minutes ago, buklu said:

Does it have ps4 emulator？

Its just backwards compatible. Dont think they use emulators for it.

[OrionFOTL]

PS5 can play PS4 games for the same reason a PC with i7 and GTX3080 can play games for a PC with i5 and GTX3060.

[syntactual]

Quote

Sony's new PlayStation 5 will have its GPU clocked for "native" tasks -- aka running next-gen PS5 games, while Gen1 and Gen0 will see the custom Navi GPU dropping its clock speeds and memory bandwidth radically to "emulate" the PS4 Pro and PS4. Gen1 will see the SoC dropping its GPU clocks to 911MHz and its memory bandwidth to 218GB/sec, and just 64 ROPs in order to emulate the PS4 Pro. The regular PS4 emulation mode on the PS5 is 'Gen0' and reduces the GPU clocks to 800MHz, memory bandwidth to 176GB/sec and 32 ROPs.

Read more: https://www.tweaktown.com/news/69542/playstation-5-gpu-9-2-tflops-36-custom-navi-compute-units/index.html

 

[PlayStation 2]

The PS5's system software was built with PS4 compatibility in mind, meaning that it retains a mode for PS4 games to run under. It allows those games to run as intended, or sometimes better than intended, if a game has a dynamic resolution setup or an uncapped frame rate. 

It's not really emulation, so much as it is making sure that software from the older, not-really-incompatible console runs mostly as intended on the newer console.

[REscobar]

The only way I cant think of how this was implemented is that on PS4 the games already ran sandboxed (aka hypervisor, virtual machine, etc) without full access to the hardware (aka bare metal), and all the PS5 has to do is provide a similar sandbox (through software trickery and a few hardware features) for PS4 games to run and an enhanced sandbox for a few select titles that run with enhanced features or are PS5 aware.

 

If this is correct, no actual emulation is required, or at least most of the code runs the same way as it did on PS4 and only a few occasional bits need to be emulated.