On Backwards Compatibility

I'm certain that many of you have been waiting for us to say something about how backwards compatibility works on Xbox 360. It is a very complex topic, to say the least. Thanks to XboxFan, a member of the backwards compatibility development team here for providing a lot of these details.

Xbox is based on a Pentium III processor, while Xbox 360 is based on a custom triple-core PowerPC processor co-developed with IBM. This is but one of many differences between the platforms, but one people are familiar with. Digging deeper, you would find that nearly everything has changed. Graphics, audio, networking, etc. have all been replaced with different subsystems.

Xbox games all run on the assumption they are being run on the exact set of original hardware. Changing anything usually means breaking some kind of behavior games depend upon. Therefore, Xbox 360's backwards compatibility had to emulate the exact configuration of an original Xbox.

One way to do this is embed the parts of an original Xbox into an Xbox 360. This was the path Sony chose to use in PlayStation 2's compatibility. However, Microsoft doesn't own the intellectual property in Xbox: it's owned by various other companies including Intel. Microsoft wouldn't have the freedom to take the parts needed for compatibility, shrink them down, and put them inside Xbox 360. And no one would want a bigger power supply any way :)

Another option is software emulation. Many of you already know this is the path Microsoft has chosen. Our software emulator works much like emulators for other platforms like SNES and Genesis. However, one key difference to keep in mind is that the Xbox emulator is emulating the immediate previous generation of games. Most emulators come out many years after a console has launched and run on PCs that represent quantum leaps in performance.

Writing an emulator isn't the same as writing other pieces of software. Other software has a lot of top-down process to it: design, prototype, revise, etc. The goal and design of emulation is pre-ordained: do whatever it takes to act like what you're emulating.

At some point, your first attempt at emulation acts like the old hardware as well as it can. At that point, you try your luck: does Halo run? The answer is both yes and no at this stage. Yes, the executable loads and starts running some x86 code, but no you don't see anything on the screen. Then it promptly crashes.

Debugging

Traditionally, when your software crashes, you fire up a debugger, step through code, and analyze the logic. Usually, source code accompanies your debugging to help you track stuff. It's quite different when you're debugging emulated software - especially software you had no hand in writing. Is the problem due to code in the emulator? Or is the code inside the emulated stuff just plain wrong? Here's what XboxFan had to say about debugging:

Debugging BC ["backwards compatibility"] is much like debugging any other software, but there are a few things that make it harder: We typically have neither source code nor symbolic information for the games we’re debugging, so we’re just looking at raw assembly code with no external clues as to what it’s doing (or what it’s supposed to do). Obviously debugging code others wrote is always harder than debugging code you wrote yourself. It’s hard to know what the code normally does, and indeed some games already have a few bugs of their own. Debugging a mixed environment -- both the emulated Xbox (x86 assembly in one address space) and the translated native code and emulator runtime (PPC code in another address space) – can also be challenging. You have to master a lot of aspects of both the original Xbox (hardware, compiler, and operating system) and the Xbox 360.

Debugging software in general is hard work. Unlike feature work, which can be meticulously planned out, estimating schedules and distributing the work among many different people, debugging can usually only be done by one person at a time and there’s no way to know up front how long the process will take. Perhaps you’ll find the bug quickly and fix it quickly. Or perhaps it will take a week to find. And while you work on it you may uncover additional bugs.

Most software developers don’t actually debug software – we troubleshoot. If a system link game is disconnecting sometimes, then it must be a problem with the networking code, right? We first look at the code that handles networking. If system link worked fine a few days ago, then we look for code changes that happened around the time it stopped working. Usually in this way it’s possible to quickly narrow down where the problem is and fix it. In contrast, debugging involves stepping through the code one instruction at a time to see exactly what it’s doing.

For BC, debugging is especially challenging. Although sometimes during our daily work we make a bad code change that temporarily causes something that previously worked to stop working, the vast majority of the time you’re debugging something that has never worked. There is no way to troubleshoot this; you have to debug the code step by step until you uncover what’s missing or wrong.

So for example, during BC development we sometimes had problems with system link games. Once it was caused by the emulator missing a cryptographic key. Another time, it was caused by a very small precision error in floating point. Yet another time, it was caused by a subtle bug in the CPU emulator that caused it to take the wrong branch in the game’s internal state machine and ultimately (millions of instructions later) disconnect.

Performance

Once you've got a game up and running, it may not perform very well at all. If you're a computer science student, you most likely understand the idea of coding a horribly performing, but correct, implementation of an algorithm - only to completely rewrite it a different way later. The same thing happens in emulation, only we get to take some shortcuts.

Luckily, backwards compatibility doesn't need to emulate things exactly right. One of the biggest problems in emulation are exceptions. Exceptions are interrupts that occur when something unexpected happens. For instance, dividing by zero, accessing memory you're not supposed to, etc. all raise exceptions. There are very few exceptions that video games care about. Many times, they will completely ignore them. When an exception occurs, many games simply crash or exit. Backwards compatibility on Xbox 360 exploits this common behavior - as well as other common patterns.

Here's some more from XboxFan:

Performance work is even harder. Once you’ve eliminated all the “obvious” performance bottlenecks, you’re left with possibilities that are neither certain nor absolute. You could change the code in this way, but it might not be faster – you won’t know until you try it. There might be several different ways to improve performance, and each way might improve some scenarios while degrading others.

When debugging, the correctness of each individual part is what matters. However, it’s not the raw performance of each individual part that matters, but the performance of the system as a whole. Individual code routines might have excellent performance on their own, but when used together one part can interfere with another in many ways (including cache effects, CPU pipeline effects, lock contention, etc.). There are so many variables and so many different things that can be measured, and the act of measuring performance affects the performance of what you’re measuring.

BC performance work differs from typical software performance work in only two ways. First of all, emulators do some highly specialized things -- like interrupt handling and very low-level memory management -- that most software programs (other than operating systems) never do. Secondly, it’s not usually the performance of the emulator itself that matters, but rather the overall performance as perceived by the emulated Xbox game. Most of our work isn’t to improve the performance of the code we wrote, but rather to improve the performance of the emulated games. Overall, we approach performance in the same way that all software developers do: Measure, make a change, and measure some more.

I wanted to speculate a little on what PS3 might be doing for backwards compatibility. Sony hasn't announced that PS2 hardware will be die-shrunk and placed inside PS2. If that's the case, there must at least be some software support for backwards compatibility. As Major Nelson noted in his podcast, Ken Kutaragi noted in a previous presentation that backwards compatibility was gated on games following TRCs (or TCRs as Xbox folk call them). I hope Sony doesn't alienate gamers based on an excuse like technical requirements. More on that in a future post, I think, since it's getting pretty late.

Comments

  • Anonymous
    April 03, 2006
    I finally got around to writing that article on backwards compatibility, with a little help from other...

  • Anonymous
    April 03, 2006
    thanks for the post! interesting, although rather identical to my tg16 emulator, despite being an ancient console :)

    i'd be interested in knowing whether it uses dynamic recompilation or if it actually software emulates all of the instructions. further, does it use the additional cores for things such as the audio processing and shader translation?

  • Anonymous
    April 03, 2006
    Fantastic start!  Will there be any more detail on the how stuff?  Is it just brute force?  Are you JITting on one core, CPU emulating on another and GPU emulating on the third? More please, this is fascinating!

  • Anonymous
    April 04, 2006
    Thanks for the article. One question though, what is a TCR/TRC ?

  • Anonymous
    April 04, 2006
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  • Anonymous
    April 04, 2006
    I do not see any issue in writing games fully in c#. The only real problem in backwards compat is what to do about possible hand optimized shader assembly. Of course you could mandate the use of HLSL ...

    How about running Singularity on Xbox N together with DX10 compatible framework..

  • Anonymous
    April 04, 2006
    I'm still crossing my fingers that Munch's Oddysee will make the list. It's the only reason my old Xbox is still plugged in!

  • Anonymous
    April 04, 2006
    That backhanded Sony comment was rich considering all the problems that have been encountered in the 360's BC.  I think you guys need to worry about the users you're alienating before being concerned about Sony's approach.

    I can certainly appreciate the difficulty in providing full emulation in software for an entire game console, but let's face facts - BC has a black eye right now.  It'll heal over time, but for now, it's probably best not to throw punches at the competition regarding this topic.

    Standard PR/marketing tactics, I know.  But what I would really like to see here is the Xbox Team focusing on the Xbox and not on what the Joneses are doing.  Any time you guys dig on the PS3, it just comes across as mildly infantile.  Why not instead just keep telling us about the Xbox and stop mentioning what the competition is doing?

  • Anonymous
    April 04, 2006
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  • Anonymous
    April 04, 2006
    Id like to see the following 2 games make the list:

    1. NCAA Football 2006 or 2005
    2. EA MVP Baseball 2005

    Both of these games have huge fan base support...

    now how about that poker on live and street fighter? whats the status?

  • Anonymous
    April 04, 2006
    OutRun 2

    Its the only great game on the xbox. Enough said...

  • Anonymous
    April 04, 2006
    I'll keep my fingers crossed that you guys succeed but if the Xbox 1 starts disappearing from shelves I might just go out an buy it.

  • Anonymous
    April 04, 2006
    There are a couple of articles that have been posted today that are worth pointing out:
    Larry Hryb...

  • Anonymous
    April 04, 2006
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  • Anonymous
    April 04, 2006
    Way back when I first heard the rumors that Xbox(next) would be using a PowerPC, all I could think was that there was NO way software emulation would be possible.  That, or we'd get performance about on par with VirtualPC for Mac!

    And now I learn that you guys have to look at assembly code!  I'm no whiz in programming, but I know that has to be tough.  It really is too bad things couldn't have worked out better in the first generation to ensure correct IP (whatever, etc.) to have hardware emulation, but for the xbox to be 4 years old, and the PS2 6, I'm very impressed with what you guys have accomplished.  I'm still very much dedicated to Halo 2, but I can slowly start to feel myself move away towards a more well rounded 360 game experience.  Although the whole 60$ game thing is kind of a barrier :-)

    Great article guys, despite the low number of comments, it's really great to get this kind of insight from the people who helped make it.

  • Anonymous
    April 04, 2006
    A very good read for anyone that thinks BC is a simple matter when you don't have the hardware manufacturers in the palm of your hand.

    Kudos to you, say I, for managing this kind of quality and optimization for software titles designed to run on one-generation old hardware.

  • Anonymous
    April 05, 2006
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  • Anonymous
    April 05, 2006
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  • Anonymous
    April 05, 2006
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  • Anonymous
    April 05, 2006
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  • Anonymous
    April 05, 2006
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  • Anonymous
    April 05, 2006
    Hey, I just was curious about something to xboxfan...

    Is there a main emulator "engine" with seperate "profiles' written for individual games? Or are all the "tweaks" made to the core engine, and that affects all games by itself?

    - Thanks.

  • Anonymous
    April 05, 2006
    Why not just let all the games play, and have a list of compatible ones. Thats how just about every emulator works. How long are we going to have to wait for each of our favirate classics to be added to the list?

  • Anonymous
    April 05, 2006
    Was there ever the thought of, instead of emulating the XBox, to just recompile the .XBE's as native 360 code where the new executables would reside on the hard disk but access the remaining data from the disc?  Would that have even been possible?

    Derek

  • Anonymous
    April 05, 2006
    So far the only ones offering any "excuses" is the Xbox Team.

    "I hope Sony doesn't alienate gamers based on an excuse like technical requirements."

  • Anonymous
    April 05, 2006
    Why didn't microsoft share this information from the start. It would have taken a lot of the concerns out of the backwards compatability issue. Up until this article I just couldn't understand why MS would go this route rather than what sony did with PS2. Good to hear. No I won't feel so bad buying a xbox360.

  • Anonymous
    April 05, 2006
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  • Anonymous
    April 05, 2006
    I think this is a great explanation of the BC process.  Hopefully enough people understand it but, from the small amount of comments I don't think they do so I have a feeling the same complaints will arise :(  However, I appreciate it and say keep up the good work :)

  • Anonymous
    April 05, 2006
    A great article, very insightful - the kind of minds you need to have to bear down on the problem of BC is seriously awe-insipiring;  these folks are a rare breed!

    It would be interesting to read a bit more about the time, how the many folks work there, how is it structured, who decides what gets worked on next (is that handed down from marketing or is it internal to the team)?   Most importantly, how do they keep sane staring hours upon hours at screens of assembler?!

  • Anonymous
    April 05, 2006
    wow...thats a lot of work for one person. i was wondering why the list wasn't updated that often. a blog for the games currently being worked on would be cool...

  • Anonymous
    April 05, 2006
    Nice article, I sold my Xbox when I got the 360, but I kept PGR2, MX vs ATV Unleashed and Stranger's Wrath, hoping they might be BC. Guys, at least Stranger's wrath needs to work, its a classic! That can be your next game to add to the list :D

  • Anonymous
    April 05, 2006
    I appreciate the difficulty involved with this process. I only hope that both the Brother's in Arms and Mechassault series find their way to the 360 sometime this year :)

  • Anonymous
    April 05, 2006
    Is there a technical reason that Capcom's 2D fighters haven't been emulated yet while complex 3D shooters like Halo have?  

  • Anonymous
    April 05, 2006
    Is there a technical reason that Capcom's 2D fighters haven't been emulated yet while complex 3D shooters like Halo have?  Marvel vs Capcom 2 and Capcom vs SNK 2 are mostly underappreciated by the core Xbox audience, but I think they are some of the best in the Xbox lineup.  It'd be great to see them on the BC list.

  • Anonymous
    April 05, 2006
    Well wouldnt even worry about it because there will be hopefully so many games being developed for the 360 that it should be great. I think that making a emulator for the 360 would be to expensive for what its worth and plus halo 2 is the only game xbox is popular for and what every xbox is used for constantly so yea i wouldt do it. My opinion what ever

  • Anonymous
    April 05, 2006
    Xbox emulation for the Xbox Team is a lot easier compared to free-lance coders. Because the Xbox Team has all the code for the kernel, all the drivers code and well they did(well most of them) work on the Xbox.

  • Anonymous
    April 05, 2006
    Im sure gald that forza motorsports works now on my 360.

    Now just give the guys at free60.org a little hint on how to run XBMC on the 360.  That way you guys dont create a monopoly by FORCING the users to use Window XP MCE!

    Peace!

  • Anonymous
    April 05, 2006
    Sence DICE has been bought out by the videogame industry distruction company known as EA I'd like to see Rallisport Challenge 2 and Midtown Madness 3 added to the BC list.

    Especially sence Microsoft won't be releasing sequels to either one.  Thanks.

  • Anonymous
    April 05, 2006
    Sence DICE has been bought out by the videogame industry distruction company known as EA I'd like to see Rallisport Challenge 2 and Midtown Madness 3 added to the BC list.

    Especially sence Microsoft won't be releasing sequels to either one.  Thanks.

  • Anonymous
    April 05, 2006
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  • Anonymous
    April 05, 2006
    I understand how hard it is to emulate a system; however it was part of M$ merchandise around xbox360, so someone has to deal with it :-|
    Nevertheless, I look foward to see Soul Calibur II in the b.c. list.

    cheers

  • Anonymous
    April 05, 2006
    Like to see Panzer Dragon Orta, Battlefront, MX Unleashed series, Soul Calibur II, and DOA series make the Backward Compatibility list.

  • Anonymous
    April 05, 2006
    When will the backward compatible games work with the vga cable? At present, no games work with the vga cable. Whenever I try an xbox game that is on the bc list my 360 tells me to change the screen resolution. But no resolution setting solves the problem. I hear it is to do with the update program requiring 50Hz. When will this be sorted.

  • Anonymous
    April 05, 2006
    3 games that should be added to the BC list sence Microsoft won't make 360 versions of them......Rallisport Challenge 2, Midtown Madness 3, and the game that should have had a sequel on Xbox....Links 2004.

  • Anonymous
    April 06, 2006
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  • Anonymous
    April 06, 2006
    Nice article. good read :)

  • Anonymous
    April 06, 2006
    Sony has run into TRC limitations in the past that resulted in maybe 10-15 games not making it through their backwards compatibility changes.

    At this time, the Xbox 360 is well over 1000 games short of fulfilling its BC promises.  While this will certainly change over time, it's probably best not to make snide remarks about the competition in this area of functionality.

  • Anonymous
    April 06, 2006
    One thing I don't understand is...they should have the actual source code available to them. Microcoft is the company that writes the emulators for the 360. And before the game goes into production, it has to be certified (by Micrsoft). In order to do that, don't they need the code?

  • Anonymous
    April 06, 2006
    Emulation of xbox games seems to be quite a complex procedure. I guess the only way for it to be perfect would be to get external games testers who know the original versions of the game like the backs of their hands to play it through noting all the issues down, and as that would take a lot of time and money. I personally think that it'll never be perfect. when I first heard about it, I thought it would be easy to emulate. Just because the new console has the xbox label, it doesn't mean that it will have the same properties. I was hoping that steel battalion would be converted, but now I know that is just a dream. keep it up, we're all behind you!!

  • Anonymous
    April 06, 2006
    It's still kinda annoying that MS can't get the games to fully work , ninja gaiden worked perfect before and now the march update has robbed the gameof sound

  • Anonymous
    April 06, 2006
    Thats great and all, my problem is more with how Microsoft (mainly the marketing side) is talking about the Backwards Compatibility like it works perfectly, using it as a selling point for the system, then I bought the system, all these problems started to arise.  All top games, Ninja Gaiden, Forza, Halo 2, Fable all had problems.  I would have also thought that once the 360 was decided to be Backwards Compatible, then all future games from that point on, would be certified for the xbox 360 emulator and the xbox, and microsoft could work with a company at the time of development, to make sure it ran fine on the emulator.

    I just feel really mislead in regards to this.  Halo 2 is a perfect example.  It STILL doesnt work right.

  • Anonymous
    April 07, 2006
    Excellent read.

  • Anonymous
    April 07, 2006
    If this is a technical article I'll feel sorry to inform you that what is stated in the article is obvious to technical people. Which path is the PS3 Followin is going to be breathtaking to say the least (as breath taking as not having backwards compatibility). I sure was hoping to see backwards and fordware compatibility! Did i ever expect the xbox360 disc to contain both, xbox360 and xbox games versions, and let the console decide which one to play? yeah I did, and I felt impressed by the difficulty and expertise doing such a thing would demand, just to name a few: devising a way to let the original xbox read the game disc, and doing, a completely different way to allow the xbox 360 read the disc also, allowing shared content on the dvd for both systems, mixing textures and making availible the texture definitions, etc). I am still waiting for that to be posible... not having to pay twice for a game and being able to play it on both (sacrificing only the quality of the graphics) would have been something without precedents... and really challenging shall I reafirm.

    And not including games but also not letting know people about what made this console great (online content, downloadable demos, backward compatibility kindof) is a hurtful fault in mexico. I assume you may get more sales if you could manage that, please do place the xbox360 comercials on market place!!! they rock.

    .-Kryz

  • Anonymous
    April 07, 2006
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  • Anonymous
    April 07, 2006
    Excellent article!  It's very interesting to look at what all you guys (or girls) have to work through to bring these BC games to the public.  Thank you for all of your hard work, and please pass on my compliments to the BC team for adding Black to the list!

  • Anonymous
    April 08, 2006
    we need serious sam 1 & 2 emulation

  • Anonymous
    April 08, 2006
    After reading that, it seems that debugging is a big issue, especially if they don't have the source code. I would then tend to think it should be easy to get all the MSG (Microsoft Game Studios) games onto the Xbox...such as all the XSN sports games, etc.

  • Anonymous
    April 09, 2006
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  • Anonymous
    April 10, 2006
    Why isn't the compability list the same for all regions (ie. a european version of a game is working, but not the american version and vice versa)?

  • Anonymous
    April 12, 2006
    Good stuff =).  I know it's hard work and I'm hoping you are able to make some monumental strides.  Not sure if this helps at all, but Cisco has made emulators for their routers and I believe that they look at designing the emulator based more on looking at the hardware rather than trying to decode the existing software.  I'm not a developer and I'm sure you've thought about this, but it just seems more logical to focus more efforts on making a pure hardware emulator (via software) than attempting to work each title's issues individually.  I maybe totally wrong, but sometimes it's the simple suggestions that make milestones =).

    Just got my XBox today and getting ready to dig into it when I get home.  Now that PGR3 is out, do you think the PGR2 developers might be able to help you guys on BC for it?

  • Anonymous
    April 18, 2006
    In my opinion, some of the more popular games that should be checked for backwards compatibility include morrowind, and DDR. I also think that Nightcaster is a good game to look up on too!

  • Anonymous
    April 21, 2006
    Instead of using an emulator, why not create some porting libraries and recompile the original xbox game source code, into the xbox 360 xdk. In this way you will have a native PPC application and also the original game developer can add extra features. You will only need to download the new executable from xbox live....

  • Anonymous
    April 21, 2006
    This article was great and there was more info about emulating than i would need... But i'd like to know more about games that will be or never be at BC.. Like Outrun2, Sega Gt Online & Taito Legends 1 & 2. ^^) You rule

  • Anonymous
    April 21, 2006
    i still dont understand how to play old games on the xbox 360

  • Anonymous
    April 24, 2006
    i hope to play doom gladius or warriors thats the only reason i got my xbox still plugged in

  • Anonymous
    May 05, 2006
    Please, Please, Please can yall try your hardess to get NBA Ballers Phenom to play on the XBOX 360 for me. I'm begging you. Thanks

  • Anonymous
    May 05, 2006
    Please, Please, Please can yall try your hardess to get NBA Ballers Phenom to play on the XBOX 360 for me. I'm begging you. Thanks

  • Anonymous
    May 08, 2006
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  • Anonymous
    May 11, 2006
    i need to know the MEASUREMENTS!

  • Anonymous
    May 12, 2006
    An update on how things are going would be good.

  • Anonymous
    May 24, 2006
    ow I so hope that morrowind is backward compatible soon :(
    and also, (this is a real n00b question, I know )if you emulate, why is it imposible to make the game believe that it's running on a normal Xbox, while using the full performance of the Xbox 360?

  • Anonymous
    May 31, 2006
    A bit rich having a dig at Sony at the end there with regard to possibly alienating gamers with the excuse of technical requirements because the entire article above is one long excuse on that exact theme. There is absolutely no viable excuse for the lack of the backward compatibility we were promised when we bought the 360. The resources available to microsoft are massive beyond belief and if they had any respect for their customers they would be getting stuck into the BC issue with everything they have. The fact is Microsoft greed means no worthwhile BC because they fear it's impact on next gen sales. We're seeing the same thing on XBLA, nothing happening because of oure greed.  

  • Anonymous
    May 31, 2006
    Thanks for the insight guys. Would be great if Morrowind could be ported some day.

  • Anonymous
    June 02, 2006
    No one is saying that implementing BC via software is trivial.

    We (the xbox gaming community) just wants you (the Xbox Team) to understand that when BC is mentioned as a selling point, we expect you to deliver on your promise. Maybe it was another Marketing not having a clue what was going on, but when I hear B.C. I expect my games to work.

    Would you be upset if it turns out that HD-DVD players can only play a subset of original DVDs after being told that HD

    "I hope Sony doesn't alienate gamers based on an excuse like technical requirements."

    I hope Xbox360 doesn't alienate gamers based on an excuse like software emulation is too hard.

  • Anonymous
    June 05, 2006
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  • Anonymous
    June 05, 2006
    The comment has been removed

  • Anonymous
    June 05, 2006
    They took the easy way out - looks like they are just putting a PS2 chipset inside the PS3.  

  • Anonymous
    June 05, 2006
    Having written a couple emulators myself, I knew this would be a difficult task. But yet, with MS walking away from the Xbox 180 so rapidly, they have little choice.

    Still irked that Forza Motorsport is listed as working when the frame rate drops to less than 6fps driving down the Esses at Road Atlanta. Forza was no performance wonder on Xbox, but it didn't do this badly.

  • Anonymous
    June 07, 2006
    I have the more expensive version of the 360 and bought a current BC disk from Microsoft. I put the disk in and downloaded what was on the disk. I've tried to play 'Fable', 'Forza Motorsports'. The are on the current list, but when I try to play them, an error message pops up "This game is not compatable with this system." Does anyone know what I am doing wrong?

  • Anonymous
    June 11, 2006
    Anyone know if Dead or Alive Ultimate is going to be BC with the 360? I noticed that DOA 3 is and can only assume that eventually this will be as well. Anyone got any info on this game yet?

  • Anonymous
    August 03, 2006
    I regularly check the backwards compatibility list on the official XBOX site and I am constantly disappointed to see that none of the Burnout games have made it on there. Does anybody know if they will make it to the list?

  • Anonymous
    August 10, 2006
        Great article, and one that I can agree with based on my own experience with emulation and technology in general.  I am especially familiar with the problem of figuring out code that I did not write.  It is always much easier when I have the developer to speak with.  This begs the question?  Should it not be easier for games developed by Microsoft to be emulated?  I do understand that there are sometimes engineering issues which seem to require the original hardware, but these are rare.  I'll just use one example here.  MS Links.  As one of the best golf simulations that I have played, this is one game that I continue to enjoy on my original Xbox as well as my PC.  It would be nice, however, if I could play it on the 360 with the 360 controller without going to the side room that I retired my Xbox 1 to.  So what gives?  Microsoft game,  Microsoft developers, Microsoft emulation team, no emulation for Links.  It does not make a lot of sense to me.  Additionally, are there not guidelines that you could send to developers for the original xbox (I know there are hardly any left now) so that all new Xbox 1 games could be more efficiently emulated?

  • Anonymous
    August 28, 2006
    I think that you guys are awesome. Keep up the good work. I am always check the backwards compatibility page to see whats new. (I can't wait for Midtown Madness 3) Again keep up the good work. (^_^)

  • Anonymous
    August 28, 2006
    Anyone have a message on the 360 with Forza Motorsport saying"The disc you are using may be dirty or damaged". I had this problem with several used discs, one of which actually worked for a couple hours. I have downloaded the updates, and the game itself updated while I was on xbox live. Any comments would be greatly appreciated.

  • Anonymous
    August 30, 2006
    My games wont work from xbox to 360

  • Anonymous
    September 02, 2006
    i think that any game rfom xbox would easley be put on the xbox 360 if one are to is put it would easley be put on others as well you just do'nt care about trying even so that all the that buy the consoles suplys for spend so much money you can do them that?if it was me i would make sure it worked one way or another.

  • Anonymous
    September 03, 2006
    Please try to make americas army: rise of a solder compatible on the xbox 360

  • Anonymous
    September 08, 2006
    Why in the name of the Great pumpkin is Morrowind not backward compatible!!!!!!!

  • Anonymous
    September 15, 2006
    The comment has been removed

  • Anonymous
    September 17, 2006
    NCAA Football 07,06,05 PLEASE!!!!!!!!!!! NCAA Football for Xbox 360 is terrible and you guys know it! Make 07 Backwards compatible!!!!

  • Anonymous
    September 21, 2006
    Morrowind?Please, please, please.So many people want to see this game made backwardly compatibile. It needn't even be the GOTY edition....I miss that game soooo much.....

  • Anonymous
    October 04, 2006
    Please, please, make Soldier of Fortune 2 , Serious Sam 2 , Doom3 Resurrection of Evil and sufferring 2 backwards compatible

  • Anonymous
    October 17, 2006
    The comment has been removed

  • Anonymous
    October 18, 2006
    Soul Calibur 2 for the Xbox. That's all we want.

  • Anonymous
    October 22, 2006
    please make doom 3 resurrection of evil, unreal championship 2 the liandri conflict, the elder scrolls 3 morrowind game of the year edition, midnight club 3 dub edition remix, conker live and reloaded, the chronicles of rdddick escape from butcher bay, dead or alive ultimate 1&2, dead or alive xtreme beach volleyball, backwards compatible

  • Anonymous
    October 29, 2006
    I would like that Microsoft finally get the backward compatibility with Mortal Kombat games, and Capcom games such Capcom vs Snk EO, Capcom Classic Collection or Street Fighter Aniversary Collection. ThankS

  • Anonymous
    November 04, 2006
    The comment has been removed

  • Anonymous
    November 04, 2006
    Snide remarks about the competition are not appreciated when Microsoft themselves can only port a few hundread titles out of thousands.  At least when Sony released their second console (PS2) they kept their promise about BC. Microsoft has yet to live up to their word.

  • Anonymous
    November 06, 2006
    Hey people, Dead or Alive Extreme 2 is hitting our lovely console soon.. I think it's about time Dead or Alive Extreme Beach Volleyball gets a Backwards Compatible patch. Please.

  • Anonymous
    November 24, 2006
    Of the five retailers that sell xbox 360 in this area, all without exception stated with absolute certainty that all the xbox series game titles would run on the xbox 360.  I was one of those consumers that believed those statements and purchased the 360 along with 3 games that did not work. I think that the incorrect information offered at the retail level is a bigger issue that actually delivering on those promises of backwards compatability.  Finding out after I have purchased this unit that the long list of playable games is not long, that even the games packaged with the unit are nonfunctional is most disappointing to say the least.  However I have already spent the money, already opened the package, already talked to support, already been dissapointed, and there is no fix for that.

  • Anonymous
    November 25, 2006
    can any please email me what normal compatible xbox can be play on xbox 360 i really need to now my email is xbox360_1988@yahoo.com.au please email if you know

  • Anonymous
    November 28, 2006
    The comment has been removed

  • Anonymous
    December 17, 2006
    The comment has been removed

  • Anonymous
    December 24, 2006
    Yeah it may be hard but we're talking about Microsoft. Throw more programmers at the problem and get more games supported! There are way fewer titles on the compatibility list then there should be.   Pleaaaase include Godzilla Save The Earth! There is no Godzilla game for the 360!! Morrowind definately too.

  • Anonymous
    December 29, 2006
    The comment has been removed

  • Anonymous
    January 08, 2007
    Please convert Strangers wrath!

  • Anonymous
    February 09, 2007
    Bloodrayne 1&2 !!! It's a must !!! And the Matrix Path of Neo too !!! Please create a patch for these games !!!

  • Anonymous
    February 19, 2007
    Would love to see either of the Godzilla games, added to the list. Thanks....

  • Anonymous
    February 19, 2007
    The comment has been removed

  • Anonymous
    February 24, 2007
    Please make sure Elder Scrolls III: Morrowind Backwards compatible, I have been waiting forever.

  • Anonymous
    March 10, 2007
    Exteremly disappointed with the Backwards compatibilty project to date.

  • Anonymous
    March 19, 2007
    i would like to see Ncaa March Madness 2006 backward compatible i love that game and i don't like the the Ncaa games or college hoops at all

  • Anonymous
    March 28, 2007
    MAKE PATH OF NEO BC PLZZZ I BEG YOU!!!  WWWAAAAAHHHH!!!!   BOOOHOOOHOOO!!!!  -_-............................

  • Anonymous
    April 02, 2007
    PLEASE!!!, I would also like to see Elder Scrolls III: Morrowind backwards compatible ^_^

  • Anonymous
    April 04, 2007
    I really hope they do Elder Scrolls 3 as well. Although I can see why it would take so long.  It has a lot different engine then most games.

  • Anonymous
    April 06, 2007
    The comment has been removed

  • Anonymous
    April 07, 2007
    why is mercenaries playground of destruction not on te backwards compatability list?? barbie and buffy are on there are you kidding me

  • Anonymous
    April 12, 2007
    The comment has been removed

  • Anonymous
    April 15, 2007
    Stupore! Amo questo luogo!:)))))))

  • Anonymous
    April 19, 2007
    Since it has been a while since the last backward compatible update I was wondering if this project is still alive and when the next update will be. I think they should still try to get all games backward compatible. I still have a few that are not on the list and I can't decide to trade them in for a few bucks each or keep waiting. Maybe the next update will be in May at the same time they update xbox360 dashboard!!

  • Anonymous
    April 24, 2007
    Morrowinds Elder Scrolls should be backwards compatible by now if any game was going to be backwards compatible it was not only a game of the year both on pc launch and xbox launch but as a platinum hit for xbox as well. Get it together man because honestly i find some of the titles that are backwards compatible not only ludacris to waste time on but were not very good games at all. Hopefully you guys will come thru for the millions wating on this one game.

  • Anonymous
    April 24, 2007
    WE NEED EMULATION FOR: Soldier of fortune II double helix                                           Serious Sam 2                                           Doom III Resurrection of Evil                                           Painkiller                                           The Sufferring II PLEASE PLEASE

  • Anonymous
    April 25, 2007
    The comment has been removed

  • Anonymous
    May 01, 2007
    Please, please, make Soldier of Fortune 2 , Serious Sam 2 , Doom3 Resurrection of Evil and sufferring 2 backwards compatible

  • Anonymous
    May 02, 2007
    Elder Scrolls III: Morrowind is a must see on the backwards compatibility list!   I personally wouldnt mind seeing Shattered Union as well.  

  • Anonymous
    May 05, 2007
    TES III: Morrowind..... I've been waiting way too long for that.

  • Anonymous
    May 09, 2007
    Any news on when there will be a patch on the xbox 360 for Taito Legends ??

  • Anonymous
    May 09, 2007
    I know this is off the topic of Backwards Compatibility , but I'll like to see games the Resident Evil series on the xbox.