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Comment by malkia | Hacker News Reader

The PS2 had an unseen graphics VRAM speed (48 GB/s), and that's why it's hard to emulate it on PS3, and maybe even PS4 (early PS3 simply included PS2 in there).

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As far as I know, all reverse compatibility at initial release that any console has ever had is by virtue of either the new console being "just" the old console with some more hardware bolted on and higher clock speeds, allowing the new hardware to be the old hardware just by turning the new features off and slowing the clock, or by simply physically including the entire previous console in the new one. I don't know of anything that ever did it by emulation. Maybe something back in the first couple of generations. I post this partially so someone will correct me, because I'm interested in the correction.

The Xbox 360 is a different architecture (tri-core PowerPC vs single core x86), but it emulates the majority of Xbox games. There are bugs, but Microsoft fixed most of the issues with popular games.

I never owned an Xbox, but I always thought that it was matter of recompiling (Xbox games to PPC) and re-releasing. I could be wrong....

While the Nintendo DS contained the CPU the GBA did, the Nintendo 3DS does not contain the DS's CPU. I assume that's either because, as they're both ARM chips, the instruction set is backwards-compatible, or that there's actually emulation happening.

The 3DS downclocks the ARM CPU and disables its second core when playing a NDS game. As a side effect, battery life is better when playing DS games on a 3DS than when playing native 3DS games on the same 3DS.

The 3DS processor is capable of emulating 8-bit systems, as it has virtual console NES and GB/GBC games. SEGA also ported some Genesis games to run on the 3DS, but I think they had to re-write parts in native ARM code as straight emulation wasn't fast enough (Google "Sega M2 GigaDrive" for a great series of interviews about this).

Some PS3s shipped with hybrid SW/HW emulation where, IIRC, the PS2 CPU was emulated by the Cell processor and the PS2 GPU hardware was included.

Wow, I didn't know this. I was so annoyed when the slim got rid of backwards compatibility but it makes more sense now. It's easy to underestimate the complexity of emulating older systems I guess.

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