Microsoft Engineer Speaks on Xbox 360 Backward Compatibility

[Guest]

http://news.teamxbox.com/xbox/8357/MS-Engineer-Speaks-on-Xbox-360-Backward-Compatibility/



blog http://www.qbrundage.com/michaelb/pubs/essays/xbox360.html

quote:

"Now that it's been announced at E3, I can finally reveal that the Xbox 360
feature I work on is... Xbox backwards compatibility!


Yes, it's real. It's been fun to watch all the wild speculation over the
past year or so as to whether the Xbox 360 would or wouldn't be backwards
compatible. And reading all the crazy ideas people have about how hard or
easy it would be.

Xbox backwards compatibility is a unique project in so many ways, and I feel
very fortunate to get to work on it. I'm sure it will be the hardest
technical challenge of my career -- I can't imagine what could possibly top
it in terms of sheer technical difficulty. It's not just the difficulty of
emulating completely different processors and devices. It's also all the
arcane knowledge I've needed to acquire about kernel-level development,
advanced graphics processing, operating systems and computer architectures.
It's changed the way I think about software.

To me, the most appealing aspect of backwards compatibility is its "magical"
quality. Normally, once you understand how something magical works, it's
much less amazing. With Xbox backwards compatibility, the opposite is
true -- the more you understand what it needs to do, the more certain you
are that it's impossible, and consequently the more amazed you are to see it
in action.

For example, some people observe the CPU and GPU architectures are utterly
different between the Xbox 360 and the Xbox, and then speculate about the
difficulties those differences pose for emulation. Without really
understanding anything that's involved, they're already convinced that
backwards compatibility is a difficult task.

Others apply more knowledge and compare the situation to something familiar,
such as existing x86 emulators for PPC. For example, Virtual PC for Mac is
great for many tasks, but gaming isn't one of them. On my 1.25 GHz
Powerbook, VPC 7 emulates a 295 MHz PC. Even solitaire feels slow, let alone
anything graphically challenging. And the Xbox isn't just any x86 machine,
it's a computing powerhouse. Emulating it seems beyond today's technology.

Other people compare the Xbox 360 against the Xbox




When I look at these numbers, I think: Wow! The Xbox is already a very
powerful machine, and the Xbox 360 blows it away. The Xbox 360 will be
fantastic for high-definition gaming!


But emulation is a difficult challenge any time the emulator isn't several
orders of magnitude faster than what it's emulating. So a few people who
understand how emulators work look at these numbers, impressive as they are,
and conclude that Xbox backwards compatibility will not work. (And then when
they see backwards compatibility working, they realize the Xbox 360 is even
more impressive than they thought!)

Finallly, there are a very few people who understand both Xbox systems
inside and out to an expert level of detail that I'm not about to go into
here. They perform more sophisticated calculations using the Art of Software
Engineering, but ultimately reach the same conclusions as those not skilled
in the Art: Backwards compatibility is impossible. One such skeptic
interviewed me for my current job, and pointedly asked during the interview
how I planned to handle the project's certain future cancellation.

And yet, here it is. It's magic!

This is part of what makes working at Microsoft so much fun -- the
opportunity to work on magical projects and do the impossible. It's a lot of
hard work, of course, but the challenge makes it fun."

 

[Paul Heslop]

wow, I'm just wetting myself with anticipation


zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

 

[Fisher]

wow, I'm just wetting myself with anticipation


zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

But, but...it's all so MAGICAL!!!

 

[Timbertea]

http://news.teamxbox.com/xbox/8357/MS-Engineer-Speaks-on-Xbox-360-Backward-Compatibility/



blog http://www.qbrundage.com/michaelb/pubs/essays/xbox360.html

quote:

"Now that it's been announced at E3, I can finally reveal that the Xbox 360
feature I work on is... Xbox backwards compatibility!


Yes, it's real. It's been fun to watch all the wild speculation over the
past year or so as to whether the Xbox 360 would or wouldn't be backwards
compatible. And reading all the crazy ideas people have about how hard or
easy it would be.

Xbox backwards compatibility is a unique project in so many ways, and I feel
very fortunate to get to work on it. I'm sure it will be the hardest
technical challenge of my career -- I can't imagine what could possibly top
it in terms of sheer technical difficulty. It's not just the difficulty of
emulating completely different processors and devices. It's also all the
arcane knowledge I've needed to acquire about kernel-level development,
advanced graphics processing, operating systems and computer architectures.
It's changed the way I think about software.

To me, the most appealing aspect of backwards compatibility is its "magical"
quality. Normally, once you understand how something magical works, it's
much less amazing. With Xbox backwards compatibility, the opposite is
true -- the more you understand what it needs to do, the more certain you
are that it's impossible, and consequently the more amazed you are to see it
in action.

For example, some people observe the CPU and GPU architectures are utterly
different between the Xbox 360 and the Xbox, and then speculate about the
difficulties those differences pose for emulation. Without really
understanding anything that's involved, they're already convinced that
backwards compatibility is a difficult task.

Others apply more knowledge and compare the situation to something familiar,
such as existing x86 emulators for PPC. For example, Virtual PC for Mac is
great for many tasks, but gaming isn't one of them. On my 1.25 GHz
Powerbook, VPC 7 emulates a 295 MHz PC. Even solitaire feels slow, let alone
anything graphically challenging. And the Xbox isn't just any x86 machine,
it's a computing powerhouse. Emulating it seems beyond today's technology.

Other people compare the Xbox 360 against the Xbox




When I look at these numbers, I think: Wow! The Xbox is already a very
powerful machine, and the Xbox 360 blows it away. The Xbox 360 will be
fantastic for high-definition gaming!


But emulation is a difficult challenge any time the emulator isn't several
orders of magnitude faster than what it's emulating. So a few people who
understand how emulators work look at these numbers, impressive as they are,
and conclude that Xbox backwards compatibility will not work. (And then when
they see backwards compatibility working, they realize the Xbox 360 is even
more impressive than they thought!)

Finallly, there are a very few people who understand both Xbox systems
inside and out to an expert level of detail that I'm not about to go into
here. They perform more sophisticated calculations using the Art of Software
Engineering, but ultimately reach the same conclusions as those not skilled
in the Art: Backwards compatibility is impossible. One such skeptic
interviewed me for my current job, and pointedly asked during the interview
how I planned to handle the project's certain future cancellation.

And yet, here it is. It's magic!

This is part of what makes working at Microsoft so much fun -- the
opportunity to work on magical projects and do the impossible. It's a lot of
hard work, of course, but the challenge makes it fun."

Transmeta managed to do it with far less resources to throw at the
problem. Albeit a design for a LP system where consumption was more of a
target than speed, but you can upgrade your CPU instruction set with
ease. Considering it only has to perform as well as (or maybe a percent
or two better) on legacy games and the original Xbox wasn't exactly
sporting a speed-demon, I don't see any reason that those targets
couldn't be hit, at least on the CPU side of things.

 

[Paul Heslop]

But, but...it's all so MAGICAL!!!

heh hehhhhhhhh

Thanks, I needed that.

 

[Dragoncarer]

http://news.teamxbox.com/xbox/8357/MS-Engineer-Speaks-on-Xbox-360-Backward-C
ompatibility/



blog http://www.qbrundage.com/michaelb/pubs/essays/xbox360.html

quote:

"Now that it's been announced at E3, I can finally reveal that the Xbox 360
feature I work on is... Xbox backwards compatibility!

<snip>

I heard that the backward compatibility will be limited to <begin crazy,
dodgy, evasive M$ quote>"top-selling Xbox games."<end quote
http://www.gamespot.com/news/2005/05/16/news_6124746.html >.

So.........once again, time will tell and speculation will make the world go
round.

 

[Doug Jacobs]

I heard that the backward compatibility will be limited to <begin crazy,
dodgy, evasive M$ quote>"top-selling Xbox games."<end quote
http://www.gamespot.com/news/2005/05/16/news_6124746.html >.

So.........once again, time will tell and speculation will make the world go
round.

Well, the article confirms that they are indeed doing software emulation.

Emulation is never 100% perfect for 100% of all games. It makes sense,
from a marketing point of view, to work on making the best selling titles
work first. This would include Halo and Halo2. It also turns out that
these are among the most demanding games in the Xbox library. So chances
are, if they can get Halo and Halo2 to work with the emulator, a large
number of other games will also work with little or no additional work.

How many and which titles will be compatible is something that can't be
answered yet.

 

[Leon Dexter]

Well, the article confirms that they are indeed doing software emulation.

Emulation is never 100% perfect for 100% of all games. It makes sense,
from a marketing point of view, to work on making the best selling titles
work first. This would include Halo and Halo2. It also turns out that
these are among the most demanding games in the Xbox library. So chances
are, if they can get Halo and Halo2 to work with the emulator, a large
number of other games will also work with little or no additional work.

How many and which titles will be compatible is something that can't be
answered yet.

Yeah, and good for them for trying. But they're 6 months away from
launch...shouldn't they have at least got Halo to work by now? When they
"confirmed" backward compatibility, and also when they clarified what that
meant, they never once said that they have even one game working yet.
It's just like everything else so far. There's 4, maybe 5 months of dev
time left, and the software they showed looked terribly rough. They claimed
that's because it's running on incomplete kits--is the hardware even
finished yet? They need to start production pretty damn soon. They
supposedly gave away 10 actual X360 units _AT E3_ (Mountain Dew promo), but
I didn't see it happen.
It just looks like they're so not ready to launch this year. If they were
launching next Christmas, they'd be golden. But right now, it looks like
everything is going to be a cluster-**** rush job.
But you know what? They had a horrible pre-launch E3 for the Xbox 1, too...

 

[HockeyTownUSA]

Yeah, and good for them for trying. But they're 6 months away from
launch...shouldn't they have at least got Halo to work by now? When they
"confirmed" backward compatibility, and also when they clarified what that
meant, they never once said that they have even one game working yet.
It's just like everything else so far. There's 4, maybe 5 months of dev
time left, and the software they showed looked terribly rough. They
claimed
that's because it's running on incomplete kits--is the hardware even
finished yet? They need to start production pretty damn soon. They
supposedly gave away 10 actual X360 units _AT E3_ (Mountain Dew promo),
but
I didn't see it happen.
It just looks like they're so not ready to launch this year. If they were
launching next Christmas, they'd be golden. But right now, it looks like
everything is going to be a cluster-**** rush job.
But you know what? They had a horrible pre-launch E3 for the Xbox 1,
too...

Problem is, E3 is a major undertaking requiring tons of resources. And if
you're six months from launching your bread and butter, I'm sure they didn't
give it the attention it deserved. Granted, Microsoft should have the deep
pockets to hire enough hands, and ensure working hardware, but it is still
understandable.

 

[Doug Jacobs]

Yeah, and good for them for trying. But they're 6 months away from
launch...shouldn't they have at least got Halo to work by now? When they
"confirmed" backward compatibility, and also when they clarified what that
meant, they never once said that they have even one game working yet.

True. It's almost as if Microsoft was caught flatfooted about this whole
BC thing. I really hope that's not the case, because if it is, it shows a
severe - maybe fatal - lack of vision and understanding of the console market
on the part of Microsoft. Yet the article from Gamespot about one of the
emulator developers would hint that there's been some pretty good progress
in that area. Sure, they don't have Halo running at hardware speeds, but
I think it would have been pretty impressive to show 360 running Halo, at
all. I guess the problem there is that most people would see this as "360
sucks" without understanding the more challenging issues that come into
play when trying to emulate hardware in software.

It's just like everything else so far. There's 4, maybe 5 months of dev
time left, and the software they showed looked terribly rough. They claimed
that's because it's running on incomplete kits--is the hardware even
finished yet? They need to start production pretty damn soon. They
supposedly gave away 10 actual X360 units _AT E3_ (Mountain Dew promo), but
I didn't see it happen.
It just looks like they're so not ready to launch this year. If they were
launching next Christmas, they'd be golden. But right now, it looks like
everything is going to be a cluster-**** rush job.
But you know what? They had a horrible pre-launch E3 for the Xbox 1, too...

That's the thing I don't understand... Microsoft should have dominated E3
this year. They should have totally and literally PWn3D Sony and Nintendo.
As it stands, it seems to me that the PS3 was further along than the 360.
Microsoft even made things muddier for themselves by mumbling something
about a HD-DVD drive "upgrade" being made available later in the 360's
lifecycle. If that's true (and it doesn't seem to have been made
official) then why buy a 360 at launch at all? Why not just wait for the
"deluxe" version to come out a year later, and take advantage of a lower
price, better hardware, and cheaper games?

Microsoft is going to have a one year jump on Sony this time. And so far,
they're not making very good use of it, in my opinion... People may point
to the fact that the Dreamcast also had a 1 year jump on the PS2.
However, I think 360 is in a better position than Dreamcast was, since
Xbox was a fairly strong console (compared to Sega's previous consoles)
and so should be able to hold its own against the Sony hype
machine...assumming Microsoft can deliver. They have to hit hard and
fast. Darnit, I *want* the decision between PS3 and 360 to be a tough one
for consumers. (I'll just get both, but you get the idea

This is a make or break generation for Microsoft. If 360 doesn't do better
than Xbox, I doubt we'll see another console from them.

 

[Doug Jacobs]

Problem is, E3 is a major undertaking requiring tons of resources. And if
you're six months from launching your bread and butter, I'm sure they didn't
give it the attention it deserved. Granted, Microsoft should have the deep
pockets to hire enough hands, and ensure working hardware, but it is still
understandable.

I don't buy that. This past E3 was critical to Microsoft.

First, it's the last major tradeshow before launch. This was Microsoft's
best chance to launch the 360 when all the industry's press was
assembled. What better time to be able to present the full promise and
power of your console than now?

Second, by launching before Sony, Microsoft has to make every day count.
They have to do everything possible to drown out the Sony hype machine.
At worst, they have to make it *HARD* to choose between the PS3 and the
360. (Hopefully they'll make it easy to choose the 360 over the PS3.)

6 months out, I would expect to at least see demos running on actual 360
hardware of launch games, not to mention a working demo of backwards
compatibility. One of the best things they could have done would have
been to have the presenter take a copy of Halo2, stick it into a 360, and
start playing it - at (near) hardware speeds.

Face it, this past E3 should have been dominated by Microsoft.)

 

[Ghost Of Dreamcast Past]

Face it, this past E3 should have been dominated by Microsoft.)

It was, in a bad way...

Those crafty console geniuses up in Redmond. E3 looks like it was
another case of what so many xbox fans have taught us before: A
Strategic Failure.

Clearly console developers and consumers are going to be impressed with
the E3 360 fiasco because it is clearly evidence of just how focused MS
is on getting ready for the 360 launch later this year - assuming MS
doesn't can the project before then - and not some silly trade show.

 

[Leon Dexter]

Microsoft is going to have a one year jump on Sony this time. And so far,
they're not making very good use of it, in my opinion... People may point
to the fact that the Dreamcast also had a 1 year jump on the PS2.
However, I think 360 is in a better position than Dreamcast was, since
Xbox was a fairly strong console (compared to Sega's previous consoles)
and so should be able to hold its own against the Sony hype
machine...assumming Microsoft can deliver. They have to hit hard and
fast. Darnit, I *want* the decision between PS3 and 360 to be a tough one
for consumers. (I'll just get both, but you get the idea

This is a make or break generation for Microsoft. If 360 doesn't do better
than Xbox, I doubt we'll see another console from them.

Well, the biggest advantage Microsoft has over Sega's Dreamcast is that
they're not flat broke. Sega was about to go belly-up more than once, and
got bailed out with loans and extensions on older loans. The Dreamcast was
doing fine, it's Sega who wasn't. Microsoft can stay in the game as long as
they want to, no matter how much it costs them, because they're still raking
in money from everywhere else about as fast as the U.S. Mint can print it.
I think the X360's year lead will help in the long run, even though it
shouldn't, from what I've seen. The way the market is right now, they'll
sell a million within a month, maybe within days, to people who wouldn't
even bat an eye if there were no games available (I'm sure you've seen 'em
around here). And they'll have a year to prepare software to roll out for
Sony's launch. It's a far, far better scenario than launching against Sony.
They'd get slaughtered and they know it (imagine how poor Nintendo's gonna
do...I bet they delay). So even a screwed-up, rushed launch is preferable.
Then they can relax for a year and probably end up a million or two ahead
when the dust settles from Sony's rollout. After that, it's anyone's game,
I think, and Microsoft, no matter how many mistakes they make until then,
will still be in the best position they've ever been in.

 

[Dragoncarer]

Well, the article confirms that they are indeed doing software emulation.

Emulation is never 100% perfect for 100% of all games. It makes sense,
from a marketing point of view, to work on making the best selling titles
work first. This would include Halo and Halo2. It also turns out that
these are among the most demanding games in the Xbox library. So chances
are, if they can get Halo and Halo2 to work with the emulator, a large
number of other games will also work with little or no additional work.

How many and which titles will be compatible is something that can't be
answered yet.

Indeedy. I think that Gamespot article aslso stated that this might be a way
of covering their arse for some games that won't work (they cited some PS1
games not working on PS2 or something IIRC).

 

[Dragoncarer]

Well, the biggest advantage Microsoft has over Sega's Dreamcast is that
they're not flat broke. Sega was about to go belly-up more than once, and
got bailed out with loans and extensions on older loans. The Dreamcast was
doing fine, it's Sega who wasn't. Microsoft can stay in the game as long as
they want to, no matter how much it costs them, because they're still raking
in money from everywhere else about as fast as the U.S. Mint can print it.
I think the X360's year lead will help in the long run, even though it
shouldn't, from what I've seen. The way the market is right now, they'll
sell a million within a month, maybe within days, to people who wouldn't
even bat an eye if there were no games available (I'm sure you've seen 'em
around here). And they'll have a year to prepare software to roll out for
Sony's launch. It's a far, far better scenario than launching against Sony.
They'd get slaughtered and they know it (imagine how poor Nintendo's gonna
do...I bet they delay). So even a screwed-up, rushed launch is preferable.
Then they can relax for a year and probably end up a million or two ahead
when the dust settles from Sony's rollout. After that, it's anyone's game,
I think, and Microsoft, no matter how many mistakes they make until then,
will still be in the best position they've ever been in.

Let's face it, the majority of people who will be buying these consoles
aren't likely to voice their opinions on this ng, nor any other forum.
They'll be buying based on:-

Marketing
Price
Game Availability
Other, pointless features.

When it comes down to it, they're not really going to care if one machine is
extremely better than the other. That's where console marketing is going:
towards the very casual gamer. The consoles will be close enough in
hardware/ performance to not make too big a difference to those buyers.

What didn't help Microsoft, IMO, was its lack of quality titles. Sony/ PS3
were able to pump the games out over the last few years, and now that the
Xbox is an established brand, I'm hoping M$ will be able to do the same.

When it comes down to it, I think that's what will decide who 'wins'.

 

[DaveC]

Writing such an emulator is an incredible job. Having first hand
experiences playing many other emulators there always seems to be some hitch
even on the best ones. I have this handheld (GP32) with many emulators on
it (www.gp32x.com). Some games will run PERFECT others will have graphical
or sound glitches, some will crash completely. For example Sonic will run
perfect on the Genesis emu but Landstalker won't run. It seems weird that
one game can run perfect but another won't on the same emulator. It doesn't
always have to do with the complexity of the game either. If one game
worked you would think they all would. Then some emulators will run
slightly slower or skip frames, on the more complex systems. Emulation is
extremely tricky.

I am really curious how well the Xbox emulator will run on the 360. If it
works at full speed, full framerate, I will be amazed.

 

[Doug Jacobs]

Indeedy. I think that Gamespot article aslso stated that this might be a way
of covering their arse for some games that won't work (they cited some PS1
games not working on PS2 or something IIRC).

The problem with comparing the PS2's backward compatibility to the XBox
360's is that the PS2 actually has PS1 hardware inside of it. And even
though not all PS1 games work on the PS2, we're talking about 5 or 6
titles out of a global library of 700 games. Unless Xbox 360 can pull off
a similarly impressive amount of BC titles, such a comparison is just
going to be detrimental to the 360.

 

[Doug Jacobs]

Writing such an emulator is an incredible job. Having first hand
experiences playing many other emulators there always seems to be some hitch
even on the best ones. I have this handheld (GP32) with many emulators on
it (www.gp32x.com). Some games will run PERFECT others will have graphical
or sound glitches, some will crash completely. For example Sonic will run
perfect on the Genesis emu but Landstalker won't run. It seems weird that
one game can run perfect but another won't on the same emulator. It doesn't
always have to do with the complexity of the game either. If one game
worked you would think they all would. Then some emulators will run
slightly slower or skip frames, on the more complex systems. Emulation is
extremely tricky.

I am really curious how well the Xbox emulator will run on the 360. If it
works at full speed, full framerate, I will be amazed.

The other thing that should be mentioned is how long these things take to
develop. Obviously having full access to the Xbox's design specs,
hardware, and even developers will help things greatly, but there's a lot
of fine tuning and manual optimization that will have to be done to get
games working at an acceptable level.

I can recall from my time with Bleem on the PC there were adjustments you
could make to the emulator yourself, and a published list of settings for
certain games. For other games, you were sort of on your own, and the
forums were filled with posts about how to get certain games running with
optimal performance.

This all takes time, and based on the progress shown at E3 (ie. nothing
ready yet) I'm pretty concerned - especially since we're looking at a
launch in about 5 months now, and it seems the hardware hasn't even been
finalized yet...

 

[Dragoncarer]

The problem with comparing the PS2's backward compatibility to the XBox
360's is that the PS2 actually has PS1 hardware inside of it. And even
though not all PS1 games work on the PS2, we're talking about 5 or 6
titles out of a global library of 700 games. Unless Xbox 360 can pull off
a similarly impressive amount of BC titles, such a comparison is just
going to be detrimental to the 360.

Ah.

 

[Smart Feet]

Can someone please explain to me why the Xbox 360 isn't "naturally"
backward compatible with Xbox games? Aren't the Xbox and Xbox 360 both
based on the Windows (2000? XP?) kernal and DirectX?

On my PC, I can change my processor and video card all I like (for a
good example, I just recently went from an Intel P4 to an AMD FX-55) and
all my games still work just fine!

Regardless of what new hardware is running the Xbox 360, why doesn't the
fact that they are running a special "console" version of Windows make
it automatically backward compatible?

Thanks...