XBox One Backwards Compatibility and Xbox One X Enhancements for X360 and OG (XO XOX BC)

[Shifty Geezer]

I'm afraid this isn't the place to ask CS questions. I'm sure there are resources on the internet to look up your answer, although your questions aren't coherent and can't be answered (XOR what with that number? XOR etc are binary operators requiring two parameters). Things like numerical conversion can be done on a decent calculator app on mobile phone. I use MobiCalc.

 

[Cyan]

I'm afraid this isn't the place to ask CS questions. I'm sure there are resources on the internet to look up your answer, although your questions aren't coherent and can't be answered (XOR what with that number? XOR etc are binary operators requiring two parameters). Things like numerical conversion can be done on a decent calculator app on mobile phone. I use MobiCalc.

yup you are right, XOR and so on would require another operand, and I didn't add a number 'cos I wrote that in a hurry, will fix that.

 

[Cyan]

I'm afraid this isn't the place to ask CS questions. I'm sure there are resources on the internet to look up your answer, although your questions aren't coherent and can't be answered (XOR what with that number? XOR etc are binary operators requiring two parameters). Things like numerical conversion can be done on a decent calculator app on mobile phone. I use MobiCalc.

I am going to give MobiCalc a try, thanks for the suggestion. I always try to simplify using powers 'cos I don't use a calculator irl as of now, but it's obvious it is a necessary evil at times.

Spoiler

this operation is tricky btw, cos the operand which is subtracting is > than the other number, but it can be done...if you know how, using C1 and C2,

find the result of this substraction using C1 and C2:

00101001
-11010110

 

[Deleted member 11852]

You're going to have to learn logical operators and they're really not that difficult. You may find your desktop OS calculator has a 'programmer' mode (OSX's calculator does) which visually expresses how the operators work see what each does. Once your know this it's really easy! There is also Wikipedia which has a really good articles on this stuff, e.g. XOR.

Good luck with your exam!

 

[Gitaroo]

did they add AA or something to the emulation? Shadow Complex looks a lot smoother than I remember.

 

[Allandor]

Fable 2, too, but that might just be better scaling or the forced vsync.
But fable 2 is just a game that was already laggy on xbox360, now it lags even more.
I hope they implement an option to deactivate it.

 

[Cyan]

did they add AA or something to the emulation? Shadow Complex looks a lot smoother than I remember.

I don't have that one, but I got the superb fun NBA Jam: On Fire Edition and also a friend gave me his Fallout 3 code -from Fallout 4- and it is an improved experience.

Spoiler

got a 9,2 score in my Network exam and a 9,75 score in my single-user Operating Systems exam, first in my class on both.

But we're told there's no recompilation.

Nope, totally full of shit. Code is not recompiled from source for the Xbox One backwards compatability.

Sorry but both of you are wrong, there is recompilation --whether it is from Little Endian to Big Endian or viceversa, I don't know, but there is-. If what's bolded isn't recompilation, what is it then? From DF:

We asked The Coalition's studio technical director, Mike Rayner, whether any optimisation or conversion was required in bundling prior Gears of War titles into the Ultimate Edition.

"It is essentially the exact same code," Rayner replied. "The Xbox team converts the 360 game and 360 flash PPC executables into native x64 executables, packages those up with the 360 game assets, 360 flash and emulator as a regular Xbox One game, and publishes it."

And this explains why we can't have immediate backward compatibility access to every Xbox 360 game in our library: the Xbox team itself seems to be recompiling the original PowerPC code to run on the x64 AMD Jaguar cores integrated inside Xbox One. This revised code is then bundled with the original game assets, along with x64-based versions of the Xbox 360 OS itself. In effect it seems that the Xbox team is able to quickly produce streamlined ports of original Xbox 360 projects. It's a remarkable achievement, and perhaps also explains why so many simpler titles are in the initial batch of backward compatible titles.

 

[Rikimaru]

Looks like 360 games do not use dirty assembler tricks much. They statically translate PPC binary to x64.

 

[BRiT]

@Cyan that is NOT recompilation. That is repackaging with static translation. Stop creating your own definition for standard terms.

 

[Cyan]

@Cyan that is NOT recompilation. That is repackaging with static translation. Stop creating your own definition for standard terms.

I am not inventing a term. This is a compiler.

https://en.wikipedia.org/wiki/Compiler

The Xbox 360 OS had to be recompiled at least for it to work as a VM. And games too...

http://www.windowscentral.com/xbox-one-uses-full-xbox-360-emulator-backward-compatibility

The instructions set of a PowerPC and X86 are not compatible

 

[Cyan]

If you don't want to call it recompiling, you can call it reassembly. But this is the reality:


http://www.redgamingtech.com/how-mi...ne-backwards-compatibility-why-sony-struggle/

Power PC (the same architecture the 360’s CPU is built in) emulation has been a ‘thing’ for computing for some time – for example, PearPC was initially released mid 2004 and is capable of running many PowerPC OSes, including pre Intel versions of Apple’s Mac OSX. The emulator does so by using JIT (Just in Time) compilation, effectively done during the run time of the application, rather than converting the code prior to the application running. Think of this (in a loose way) of being similar to how a Genesis emulator runs, with the software emulating the functionality of the Genesis’ hardware as the game software runs.

And you don't know how it works, nor do I, but I am more likely to be right because some recompilation has to be going on:

Microsoft are keeping rather quiet on the exact technical methods they’re using for the emulator (which isn’t surprising) – but the take home message is that Microsoft’s engineers have managed to a rather impressive feat. The ‘virtual 360′ is effectively an Xbox 360 emulated

“This time,” said Spencer, “the team took the approach of effectively running the whole hardware OS that was running on the 360 hardware on the Xbox One. So when you boot the games, it literally boots up the operating system of the Xbox 360 – which is why you can play with Live and everything else. That was the most difficult thing.”

 

[BRiT]

Recompilation involves source code. They do not have the source code. Stop trying to redefine standard terms.

 

[BRiT]

JIT compilation is a runtime optimization and only has to do with languages which have an intermediate instruction target such as those run under a virtual machine like Java or C#. Console game engines do not use either of those. That is not recompilation.

 

[Cyan]

Recompilation involves source code. They do not have the source code. Stop trying to redefine standard terms.

Okay, say you are right... How do you know? Did you talk to the engineers? Even if the code isn't recompiled, which you and I don't know... the games are clearly recompiled for the Xbox One!! Otherwise you would not have to download the flash and the ENTIRE game whether you own the disc or not.

This means that they aren't emulating the Xbox 360 hardware, just recompiling Xbox 360 code for the Xbox One.

 

[BRiT]

I'm sorry, but I cant help you since you refuse to accept the obvious and keep redefining standard terms.

 

[BRiT]

During multiple XBox One related interviews they directly said they are NOT recompiling X360 games to run on Xbox One. They directly stated they are repackaged with an application that runs and emulates the X360 system.

 

[Rockster]

Oh no, here we go again. I understand why people think there is no re-compilation based on information provided during previous interview, and why those responses were given. However, the x360 emulation on x1 is using ahead of time compilation and newly linked x64 executables.

 

[BRiT]

Oh no, here we go again. I understand why people think there is no re-compilation based on information provided during previous interview, and why those responses were given. However, the x360 emulation on x1 is using ahead of time compilation and newly linked x64 executables.

Right, as said it uses repackaging with static translation, which is not recompilation.

 

[BRiT]

I think what is confusing some is what parts receive what actions.

The X360 OS System was created as an XBox One Game. This did involve using original X360 OS System source code and compiling it from source to target x64 XBox One Platform.

Each Individual X360 Game set to run on XBox One through the Backwards Compatible layer. This does not involve using the original game source code and compiling to target the Xbox One [recompilation step would be here, but it does not happen]. Instead, the binary artifacts of the game have been put through an ahead of time static translation to shift it into something suitable to run on the x64 Xbox One Backwards Compatible layer. The results of this are then repackaged as a x64 Xbox One game.

 

[Cyan]

Oh no, here we go again. I understand why people think there is no re-compilation based on information provided during previous interview, and why those responses were given. However, the x360 emulation on x1 is using ahead of time compilation and newly linked x64 executables.

I think what is confusing some is what parts receive what actions.

The X360 OS System was created as an XBox One Game. This did involve using original X360 OS System source code and compiling it from source to target x64 XBox One Platform.

Each Individual X360 Game set to run on XBox One through the Backwards Compatible layer. This does not involve using the original game source code and compiling to target the Xbox One [recompilation step would be here, but it does not happen]. Instead, the binary artifacts of the game have been put through an ahead of time static translation to shift it into something suitable to run on the x64 Xbox One Backwards Compatible layer. The results of this are then repackaged as a x64 Xbox One game.

Rockster has said that the emulator is using ahead of time compilation, and you call it repackaging and seem to agree with him? Plus you mention compiling several times, so in the end, you are also saying it is a compiled emulator, just not the games themselves but the OS --from your words.

You are probably right there. However, what does explain that games must be repackaged and even if you own the disc you must download the digital copy? Wy games don't use the same space even if we subtract the emulated flash space?

This PDF shows how to build a X360 emulator, and compiling is mentioned everywhere:

http://digiex.net/attachments/downl...x-360-emulator-building-xbox-360-emulator.pdf

Xenon_(CPU) • 64-bit PowerPC w/ in-order execution and running big-endian • 3.2GHz 3 physical cores/6 logical cores • L1: 32KB instruction/32KB data, L2: 1MB (shared) • Each core has 32 integer, 32 floating-point, and 128 vector registers • Altivec/VMX128 instructions for SIMD floating-point math • ~96GFLOPS single-precision, ~58GFLOPS double-precision, ~9.6GFLOPS dot product

Xenon uses in-order execution – great for simple/cheap/power-efficient hardware, but bad for performance. Optimizing compilers can only do so much, and instruction streams meant for in-order processors should always run faster on out-of-order processors like the x86.