Java-Based x86 Emulator

jaavaaguru writes "Researchers at Oxford University have produced a Java-based x86 emulator that they hope will be useful in testing applications and learning about viruses without damaging the host, utilizing the robust sandboxing that Java provides. They have an online demo available that boots DOS and has some games to play. Being purely Java, this emulator should be able to run on almost anything, including cell phones." The code is not yet available outside the Oxford community; the developers are said to be working on a suitable general license. In the meantime the code can be licensed on a case-by-case basis.

Interesting, but

[dreamchaser]

I can only imagine that this will make even Bochs look fast in comparison!

Still, I'd love to tinker with this from a 'gee whiz' standpoint.

Re:Interesting, but

[Qwertie]

I'd have to agree. Using instruction-by-instruction emulation, a C++ based SNES emulator I wrote around 1998 used at least 150Mhz of processing power to emulate the SNES' 3Mhz processor. When I rewrote it in assembly, it was 5-10 times faster. I expect that some pretty sophisticated techniques would be required to exceed a snail's pace when using Java for emulation, eg "dynamic recompilation": translating sections of x86 machine language to Java bytecode... but getting this to work 100% correctly would be pretty tricky.

If it's hard to get good emulation speed in C++, it's even harder in Java.

can you run java in the x86?

[leuk_he]

THe next question would be: can you run java in the x86 emulator that runs an other emulator that runs java, that runs an other emulator.

Just like the old days when you ran windows real mode under a windows 386 mode windows.

Re:

[faragon]

Why not? Just you get execution speed and available memory progressively downgraded/shrinked (doing it ad infinitum or ad nauseam [slashdot.org], until you're out of memory for the next emulation context) :~P

Re:

[idonthack]

...or would you?
Linux on emulated hardware can be faster than Linux on real hardware:
http://linux.slashdot.org/article.pl?sid=06/05/31/ 0641207 [slashdot.org]

Re:can you run java in the x86?

[timeOday]

Linux on emulated hardware can be faster than Linux on real hardware:

There you go, a perpetual speedup machine. Run enough layers of Java on X86 on Java on X86 and supercomputers will be replaced by Cyrix 386s.

Re:can you run java in the x86?

[Citizen of Earth]

The next question would be: can you run java in the x86 emulator that runs an other emulator that runs java, that runs another emulator.

...written in XSLT.

Re:

[The_Wilschon]

Oh, I was going to write it for a Turing machine, running in Conway's Game of Life [rendell-attic.org], implemented in Postscript [tjhsst.edu].

Re:can you run java in the x86?

[Cyberax]

Yes.

The next step is to get rid of hardware altogether.

Re:

[Pseudonym]

It's turtles all the way down, I tell you!

Re:

[saboola]

If I might ask, what emulator was it? I have been an emulator nut for a little over a decade and would love to know if I used yours.

Re:

[Victor Antolini]

A little bit of searching brought this [netfirms.com]

Btw, here's a Gameboy emulator [pscode.com] written in Visual Basic!
It's quite fast... puzzling.

Re:

[chorltonian]

Errm... how about trying it out before judging it? As has been covered god knows how many times before, Java is capable of runtime optimisations not possible with statically compiled languages like C++.

Re:Interesting, but

[shaitand]

'Java is capable of runtime optimisations not possible with statically compiled languages like C++.'

And with them it can perform almost as fast as C in some fringe cases.

Re:

[heinousjay]

Awesome, you've successfully combined unnecessary anger, anecdotal evidence, the arrogant assumption that only your opinion matters, a Slashdot meme, and a bunch of insults into one post. I think you get some kind of award for that.

Re:

[Citizen of Earth]

Java is capable of runtime optimisations not possible with statically compiled languages like C++.

There is a world of difference between "theoretically capable" and "reliable does". Is there some practical demonstration that compute-intensive tasks like emulation can be reliably executed with Java without sucking?

Re:Interesting, but

[Anonymous Coward]

Don't you know, around here:

• All Java is slow
• All Perl is unreadable
• All PHP is insecure
• All JavaScript is a useless intrusion into your browser

... and all comments like those are written by "experts" who've never written one line in the language in question.

Re:

[ConceptJunkie]

Ridiculous! Java can perform NOPs as fast as any compiled language.

Re:

[shutdown -p now]

Much faster, actually, thanks to its opportunity to perform runtime optimizations. Why, I've even heard rumours that it can extremely effeciently parallelize particularly long NOP loops!

Re:

[RzUpAnmsCwrds]

All Java is slow

Compared to C++, yes, it typically is. But it's usually within 20-30%, sometimes a bit worse, sometiems a bit better. In some rare cases, Java can even beat machine-code compiled languages.

All Perl is unreadable

Absolutely not. But Perl culture encourages the kind of programming which leads to unreadable code. And Perl syntax certainly doesn't help either.

I would much, much rather work on Java code that someone else wrote. It's not that you can't write horrible Java code, it's just that the l

Re:Interesting, but

[MobyTurbo]

Errm... how about trying it out before judging it? As has been covered god knows how many times before, Java is capable of runtime optimisations not possible with statically compiled languages like C++.

Maybe so, but it is running much slower than DOSEMU or DOSBOX does in Linux here, which are probably written in C or C++, with possibly some assembly; and can do emulation of all the games it emulates. Java is indeed capable of certain optimizations that are not done in a non-JIT compiler, but that simply is because it needs them. Anyone who tells you that Java operating system emulators typically run faster than C operating system emulators has been smoking SUNW crack. That having been said, there are reasons for choosing Java over C. One of them is built-in security sandboxing, which was obviously the reason for the choice.

Re:

[tomhudson]

Errm... how about trying it out before judging it?

errm ... how about because the applet failed to load?

If you go to the site, you'll see their premise is stupid - that game companies will license this to sell old dos games on cell phones, rather than porting them. Of course what they overloook is once you have the emulator, you don't need the game companies - just go through any abandonware site, or your stacks of old floppies.

Re:

[mgiuca]

"dynamic recompilation": translating sections of x86 machine language to Java bytecode...

Which then gets dynamically recompiled by the Java VM into x86 machine language :)

(At least, when running on an actual x86).

Seriously though, this is quite impressive (to have it written in Java). But what are the advantages of this versus QEMU? (Besides a wider range of platforms). I mean... QEMU already offers total sandboxing doesn't it?

Did you try it?

[Ron Harwood]

It's not bad - admittedly it's running DOS - but Prince of Persia seems to run nicely.

Re:

[Wesley Felter]

Sure, an x86 interpreter written in Java is going to be pretty slow, but a JIT written in Java beats a C interpreter (bochs) any day.

Re:

[mrmeval]

Why Java? Qemu works as does VMWare and others....

So...

[mriya3]

... now we should say: "x86 assembler: write once, run everywhere (slow as molasses in January)" ?

Molasses - 35mph!

[Anonymous Coward]

not that slow if there's enough of it! [wikipedia.org]

Re:

[eclectro]

... now we should say: "x86 assembler: write once, run everywhere (slow as molasses in January)" ?

You know what would really be kewl? If you could make an integrated circuit that runs java real fast then you would have a chip that runs x86 assembly.

Re:

[shaitand]

'You know what would really be kewl? If you could make an integrated circuit that runs java real fast then you would have a chip that runs x86 assembly.'

Why wouldn't you just grab a Pentium 266 and have a chip that runs x86 assembly at twice the speed this thing will on my dual core athlon?

How's the efficiency?

[lbft]

Whilst this looks like a really interesting project, I'm failing to see how it's useful generally due to the limitations of writing it in Java and making it cross-platform. You would lose a lot of those possible (processor- or platform-specific) optimisations that make the leaders in the virtualisation market as fast as they are.

On, say, a mobile phone (which is mentioned by the site as a possible use) would there be enough processing grunt to do anything useful? I know Java's not as slow as some people wou

Well for one

[brunes69]

For one this will let you run X86 DOS applications on a SPARC for example.

I'd like you to point me to the support page for VMWare on SPARC... oh wait that's cause there isn't one. QEMU can't even run most applications on a SPARC.

And forget about ARM.

I think this is great. Java is not as slow as people seem to think it is. One thing Java 5 (and 6) have that actually benefits virtualization is dynamic recompilation... the JVM knows the instruction sdequences better than the original author, and in theory can optimize the code paths in ways writing a virtualizer in assembly or C++ can not.

Re:

[EvilIdler]

Java isn't all that slow, but the bad rep is because of its startup time and a really unoptimised GUI.
It's fine for all sorts of things while running, but the two apps I use it for aren't exactly impressive.
If I leave Azureus up for a while, it's eating 400 megs of memory. It also takes 10+ seconds to show
its window. The other thing I regularly use Java for is my bank, which insists on using a friggin'
control in its window. It takes about a minute to show up, even with other Java apps running. It seems
the s

Re:Well for one

[daeg]

If you are using Firefox with Java and having ridiculous applet startup times, you need to disable your Java Cache. This is Java's fault, not Firefox's (supposedly).

Under the Java control applet, under the General tab, click "Settings..." under "Temporary Internet Files". Then click "View Applets...". It will take a moment to load (or in my case, 2-3 minutes). Then UNcheck "Enable Caching". Firefox now starts my applets almost instantly. This doesn't affect downloaded Java applications such as Azureus or Eclipse (both of which I use extensively).

Hope this helps.

Re:

[jimmydevice]

I did something even slower in 1973. A Cardiac ( Bell Labs cardboard computer ) emulator written in FORTRAN, running on a FORTRAN emulator written in HP 2000 BASIC running on a HP2100 mini. Cycle time = one instruction / Sec.
It could play tic-tac-toe, Very slowly.

Re:

[Nasarius]

I recently installed Eclipse, and it's a world apart from the slowness of the bank webapp and Azureus. Starts up immediately, ready to rock. I may start using it once I figure out how :P

Really? Last time I used Eclipse (3.0M6, I think?), it was just as sluggish as Azureus. A shame, since it's an incredibly powerful Java IDE, and not half bad at C++ and Python. I just wish it used shareable project files, not the .workspace mess.

Re:

[AdamInParadise]

Project files (.classpath and .project) in Eclipse are shareable, with a few caveats. If you want to share them across developers, you need to enforce some stricts rules and sometimes it's not worth the shot. Also, do not checkout projects in .workspace.

Re:

[AdamInParadise]

This difference in startup times between Azureus and Eclipse is surprising. Both are based on the same framework (RCP) and I will argue that Eclipse is "bigger" than Azureus. On my box, the startup times are similar. How many torrents are you trying to download? Also, are you sure that Azureus is started in a recent JVM (like 1.6) instead of some ancient 1.4?

Anyway, in Java, each process runs in a different JVM, so there is absolutely no sharing between processes. This is a long-standing issue and Sun is cl

Re:

[VGPowerlord]

Eclipse and NetBeans are both written in Java, albeit with different GUI toolkits. Eclipse uses SWT [eclipse.org], while NetBeans uses Swing [sun.com].

You'd think that Eclipse would be faster due to SWT interfacing with the native widget set, but I guess this shows that GUI speed isn't everything. As a side note, Azureus also uses SWT.

Re:

[caseih]

QEMU is listed as fully supported on SPARC. Both the full hardware emulation (full machine requiring an OS) and Linux-on-Linux mode. The emulated CPU also does dynamic translation so the speed hit shouldn't be nearly as bad as bochs and this java emulator.

Still, though, your point is taken. This emulator could run x86 software anywhere the JVM is. Of course the primary purpose of it seem to be for research purposes (debugging rootkits, etc). Whether it will metamorphose into something practical remains

Re:

[Nasarius]

For one this will let you run X86 DOS applications on a SPARC for example.

DOSBox already runs on SPARC, as it's a full emulator.

Re:

[sumdumass]

I don't think this is meant for a general purpose vitalization application. This is more or less a research on what something does project. More specifically, You can take a virus and run in it a way to compromise the virtual machine without compromising the machine itself. This means your output is not likely to be damaged in any ways as well as you can monitor the activity from a removed setting while maintaining a presence.

And this wouldn't be just limited to a virus program either. Suppose we had this a

Re:How's the efficiency?

[slamb]

More specifically, You can take a virus and run in it a way to compromise the virtual machine without compromising the machine itself. This means your output is not likely to be damaged in any ways as well as you can monitor the activity from a removed setting while maintaining a presence.

Well, that's great, but you can already do that with VMware, Parallels, QEMU, or other virtualization tools. Sure, virtualization requires the same host and guest architecture, but we all have plenty of x86 machines sitting around, and near-native speeds are necessary to actually boot Windows Vista before the sun goes supernova. So while this is neat software, it's not as suitable for malware researchers as what they are already using. The JPC project needs to find a different niche.

Re:

[shaitand]

'and near-native speeds are necessary to actually boot Windows Vista before the sun goes supernova'

near-native? You'd better not only have a native system but a rather fast one to boot Vista in a timely manner. But its all worth it, because you can windows+tab and see a cool 3d cascade of windows. I don't even mind so much that they arbitrarily rearranged all the menus and control panel functions (without adding anything of use) for no apparent reason. All is good just so long as I can see window contents m

Re:How's the efficiency?

[kestasjk]

near-native speeds are necessary to actually boot Windows Vista before the sun goes supernova.

The sun isn't close to large enough to end in a supernova; it'll be a red giant, then end as a white dwarf.

Re:

[slamb]

Thanks for the correction - an unthinking attempt at hyperbole on my part.

I'll try again - by the time you boot Vista under this emulation, the Sun will have become a red giant, Earth's seas will have boiled away, and its atmosphere will have escaped into space, or at least you'll feel that way... If you were play back a time-lapse of the boot process so that Vista appeared at normal speed, you would look like the villain in Indiana Jones and the Last Crusade after he drank from a false chalice.

Re:

[Gromius]

Actually I think it is for general purpose code. In fact I think its main purpose is for running general code on the grid [wikipedia.org] and giving each process its own virtual sandbox, isolating it from the underlining hardware. This means that some random grid user wont be able to hose the machine they happen to be using which should make things easier from a grid admins point of view. Its the only reason I can possibly think of why they made it.

Incidently when I first heard about this today, I thought it would be the

Re:

[suckmysav]

Yes? And? I'm stll waiting for the second word I was promised . . .

Java x86 emulator speed

[christurkel]

Java only: snail speed
Java+DOS: Snail with ball and chain
Java+DOS on non x86: Snail nailed to the table

Java isn't really slow...

[Belial6]

Java isn't really slow when you consider that it is an emulator. As emulators go, Java is down right zippy. Of course everyone seems to forget that it IS an emulator.

So it runs DOS eh?

[ookabooka]

But can it run Linux. . .?

Why did they use Java? It would have been faster in C++.

I for one welcome our new old x86 overlords.

Did I miss any?

Re:So it runs DOS eh?

[HoosierPeschke]

In Soviet Russia x86 emulates Java?

Re:

[rrohbeck]

>Did I miss any?

In Soviet Russia, Java runs x86!

java me is not java se

[Billly Gates]

It will take some work to port.

But still cool though.

Re:

[pjt33]

Java ME isn't a single configuration or profile. It's probably not too hard to port to CDC/PP, but CLDC1.0/MIDP may be trickier.

What do you do when it crashes?

[CTho9305]

I was playing around with DEBUG.COM and ran "OUT 20, AX"...and now it's apparently dead [ctho.ath.cx]. A lot of things don't seem to work - e.g. "mode 80,20". Even "dir c:" when the current drive is "a:" seems to hang. I wonder how complete the hardware emulation is. Can you run Windows 3.1 on this? How about programs that probe for a joystick?

Re:

[ScrewMaster]

All I know is, if it can't run Duke Nukem Atomic Edition, Shadow Warrior or Blood it's useless.

Re:

[Eudial]

I was playing around with DEBUG.COM and ran "OUT 20, AX"...and now it's apparently dead. A lot of things don't seem to work - e.g. "mode 80,20". Even "dir c:" when the current drive is "a:" seems to hang. I wonder how complete the hardware emulation is. Can you run Windows 3.1 on this? How about programs that probe for a joystick?

It isn't dead! For crying out loud, it's java! It's still processing the instruction... Come back in September for the result.

Re:

[jrumney]

It seems they forgot to emulate the bluescreen.

on a good Java runtime...

[dshk]

if the emulator itself runs on x86 then the just in time compiler of the Java runtime may optimize the code enough that we get back almost the original assembly code... but without any buffer overflows and other security problems - theoretically.

Other projects doing the same/faster thing..

[Boj]

There are at least 2 solutions doing a similar thing. The open source binarytranslator.org/PearColator offers x86 and PowerPC emulation:
http://binarytranslator.org/ [binarytranslator.org]
There are attempts to integrate this into the JNode open source Java OS to make a JNode/GNU stack.

There is also the VEELS/JXEmu system:
http://nil.ics.uci.edu/~gal/?page=VEELS [uci.edu]
which appears not to be publicly available.

My intepretation

[Excelcia]

An interpreted language being used to write an opcode interpreter.

For an encore, perhaps they can write a JVM in BASIC.

WARNING: Performance implosion imminent due to recursive interpretation.

Re:

[batkiwi]

I know you're being funny, but Java isn't interpeted any more than C is. Both are compiled to produce machine code (one meant to be run on a virtual machine, one by a native one, but nothing's preventing someone from making a hardware JVM).

Virtual Machine Advantages

[CustomDesigned]

There are a lot of applications that are not CPU bound, including business and accounting, but have a *lot* of code. We have used virtual machine code since the 1970s. When upgrading the hardware and/or OS (from Series/1 to 286 AT Xenix to Motorola 68020 to Motorola PPC to AIX to Linux), we just copy the applications and data. No mess, no fuss.

I can also think of a lot of applications that are *not* appropriate for virtual machines because of CPU performance demands. The right tool for the job and all

Re:

[batkiwi]

Fine then, according to YOUR comments C is an interpreted language. C compiles to assembly, which is then INTERPRETED into machine code.
Also, your point of "It's to illustrate that Java and JVMs were a step back technologically, just like .NET" shows quite a bit of ignorance. In an enterprise environment, which is more expensive: Developer time, or more/faster servers?

license

[pmsyyz]

Do me a favor and don't pimp software until we can be sure it is non-proprietary.

Re:

[mohjlir]

So should we just run OSS news? Then all the MS trolls would have to get jobs! Seriously, this is news no matter what the copyright holders intend to do (or charge) for the software.

Why not Simics?

[Anonymous Coward]

I can get Simics for free if I am an academic and Simics gives over 300 MIPS on 2GHz AMD64s (and probaly a lot more on the Core 2 CPU). I really fail to see the use of something that probably is dog slow, written in Java, and probably cannot do reverse execution. Oh, btw, Simics does x86, x86-64, SPARC V8/V9, PPC32/64, MIPS32/64, ARM and perhaps some more.

Can someone explain the advantages of the Java based x86-emu in TFA over something like Simics?

I tried the demo, but it didn't work

[Master of Transhuman]

via my Firefox on Kubuntu using the Java 1.5 plugin.

The demo started up okay, booting and getting to an A: prompt. But it wouldn't accept keyboard focus so I couldn't enter any instructions to run any of the games.

I contacted the project to let them know. They responded that I probably need to upgrade to Java 1.6 to insure keyboard focus. It's also possible that one of my Firefox extensions might have interfered. They said they have tested JPC with Firefox and Linux but not with Kubuntu specifically.

I was s

Re:

[Nasarius]

I got the same problem with Konqueror and Java 1.6. No keyboard focus. *shrug*

Re:

[gkhan1]

It did that to me at first to (I'm running Firefox under Ubuntu), but after reloading the page a couple of times, and making sure that the applet was the first thing I clicked, it worked fine

A bigger problem for me is that I use a non-US keyboard which means that it I couldn't do anything because I couldn't change the locale so when I typed ":" it entered ">". Meaning I couldn't do anything since I couldn't change the drive to c :) Anyone got a fix for this?

Re:

[cecom]

Same problem here with Firefox and JDK 1.5. Shrug.

Java is fine for emulation

[tezza]

[1995] When I was at university [unsw.edu.au] on Java 1.0, we were taught operating systems on emulated Minix [minix3.org]. It was fine then, no reason x86 won't be fine now.

Just give this project time. Everybody is queuing up to knock it down, but it should be fine. They're not planning to put Vista on it, just emulate some DOS data entry applications.

Re:

[jsight]

What? Where would you get an emulated Minix that runs on Java?

What is the point?

[chrysalis]

Sorry, but I don't get the point.

Viruses also need OS system calls to do the job. Unless there's also a full Windows emulation in Java (including the Windows bugs and vulnerabilities viruses depend on), how could this be used to analyze how viruses are working? And even if it was the case, what would be the point over QEmu?

If you need to understand what some piece of code is doing, there are tools called debuggers.

Re:

[JustNiz]

Do you realise Windows isn't the only (x86) OS in the world? Actually there are far better ones out there....

Re:

[jilles]

The point would be that it can be done. They're academics.

Having proven that it can be done and having proven that it can be done properly, they effectively prove you and other nay sayers wrong. They are claiming that it works and that it works with acceptable performance (for an emulator). A little out of the box thinking sometimes produces nice results. Why bother with C based emulators if you can do the job in the much more developer friendly Java? As I said, they're academics and probably have better th

Wait for the lawsuits...

[DigitAl56K]

How much of the x86 instruction set has patents attached to it?

You probably wouldn't see the likes of Intel suing x86 emulators running on x86 (e.g. virtual machines), but it might be a different story if people start using x86 emulators on other CPU architectures through a Java VM because that cuts into their business.

Re:

[frogstar_robot]

DOSBOX has been around for awhile and uses an emulated CPU. It works well enough to run DOS games and Windows 3.1.

Re:

[DigitAl56K]

Nearly every distribution of DOSBOX is for x86 hosts. The point is that a Java emulator will have more widespread application.

Slow

[andreyw]

Slow by definition. I wonder if you can use JIT techniques with java at all, but in the end, it still would have to be converted to native code.

Also, for something that's is apparently non-FOSS, they seem to be using both the BOCHS BIOS and the VGA ROM BIOS.... Now the VGA code is AFAIK LGPLd, so they should be okay unless they modified it (a possibility) but I'm pretty sure they had to modify the stock Bochs BIOS, unless they emulated Bochs. In either case, the Bochs BIOS is GPLd.

Won't accept all keystrokes

[harmonica]

Renders my entering : as a > character (German system). Any other way to change to the c: volume?

The next step

[Myria]

The next step will be for Microsoft to embrace-extend-exterminate the design for .NET, then use it to run legacy applications on a new OS that locks out native code and unsigned code.

(This is cynicism - I'm not being too serious.)

Quite interesting

[Orion Blastar]

Because this means non-X86 systems can finally run X86 code. Even if it is slow, it is better than not running X86 code at all. I assume it is a virtual X86 CPU in much the same way that MAME and MESS emulate CPUs via software.

I understand that until they are able to fully emulate certain hardware than this could be limited to just DOS programs. I think they at least out to be able to emulate a S3 Virge video card, Sound Blaster 16, Intel Chipset network card, and maybe serial ports with a Hayes compatible

Re:

[dreamchaser]

It is interesting from the standpoint that the emulator itself *should* be fully portable to any platform that runs java. It's probably not useful commercially but from a geek standpoint it could be cool.

Re:

[dreamchaser]

Both of those need to be ported to the target OS that they will be hosted on. A java based emulator doesn't need to be ported.

Re:

[badfish99]

A java based emulator doesn't need to be ported.
That's the huge advantage of java. Just port the 100 meg or so of JVM, throw in a faster processor and a few more gigs of memory, and it'll run on anything.

Re:

[bluefoxlucid]

Most of Sun's JVM is in Java. It's like Minix: Kernel is in low-level kernel mode, while services are in user mode and use an interface to the kernel, and other services in user mode use those services, and userspace apps utilize those services. In Java, though, you're abstracting away from the hardware rather than from other software; so some part of Java (the JIT) is in a mix of C and assembly; while some other part of Java is in Java; while some other part of Java uses that part of Java and is written

Flamebait??

[Weaselmancer]

Hey mod, I'm serious and I'm making a serious point.

Porting the JVM somewhere is about as much effort as porting a word processor, or any other 100 meg application. But if you port the JVM, all the applications you have in Java are ported by proxy. It's a one-time task.

So if your 100 meg word processor is in Java, once you port the JVM you get the word processor for free. And all of your other Java applications. You don't have to port them seperately. It's one porting task and then you're done.

An

Re:

[bluefoxlucid]

Because emulators are special. Now P2P clients on the other hand.. well, LimeWire Windows, LimeWire OSX, LimeWire OS9... hey at least LimeWire has a single port for BSD *and* Linux, no need to port there.

Re:

[gravis777]

Since when did emulators become news on slashdot? Its still buggy too. No mouse support (makes playing Lemmings a pain), graphic corruption in some places in Lemmings, arrow keys get effed up when playing Prince of Persia, no sound support, and, well, its kinda slow. Some lagging in Prince of Persia, and I am on a p4. Now, did the original post say that they wanted to use this to test viruses? Please tell me they are not planning on installing windows on this thing.

Although I would smile if they installed W

Why Java ?

[DrYak]

I do understand the reasons they chose the language

I don't. What does Java has to offer that some standard C emulator doesn't ?
Some of the current emulators provides special hooks so the emulated code can ask the emulator to perform some task for acceleration (like some emulators provide special graphic and network drivers for the emulated Windows).
But if you cut them, there are no differences between the emulator and a real machine from the virus' point of view.

If the emulator is well done enough there won

Re:

[suckmysav]

"What does Java has to offer that some standard C emulator doesn't?"

Can you compile C apps to run on your phone? I know I can't.

Re:

[Xymor]

They claim 10% native speed, which is somewhat fast in terms of emulation.

Re:

[animaal]

If this webapp. survives a lot of geeks messing and hacking about in that virtual machine I'd be very tempted to label this as a very interesting experience when it comes to the Java robustness factor.

There's no danger to the virtual machine. The emulator and disc images are all run within the browser. So each browser receives its own emulated memory space and fresh disc images. No processing occurs on the server (except for serving the application code and disc images to the browser).

Compared to what?

[alienmole]

You're missing something here. Sure, Java is faster than some languages like Python or Ruby or PHP, but that doesn't necessarily put it in the realm of languages that are a good choice for implementing hardware emulators. There are many other languages that would be faster and, at the same time, more high-level than Java. (The ML family comes to mind.) The Java sandbox argument they use in this case is rather bogus - if you're writing an emulator, you can easily build sandbox functionality into it. In

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[alienmole]

If the purpose of this emulator is just to run DOS, DOS programs, and programs of similar size, then perhaps implementing it in Java is "acceptable", as you say. However, DOS ran happily in 640KB of memory or less, on CPUs that started from 4.77 MHz. That's why it's possible to emulate it successfully on modern hardware, because the hardware now has clock speeds nearly 1,000 times faster and memories more than a thousand time larger. To emulate more demanding systems, better performance would be needed,

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[digitig]

That was decisive for me -- until I tried playing it. The keyboard handling is broken. Why bother porting games, they ask? Because that way they work. Neat idea, premature release.

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[BiggyP]

Hmph, it is indeed CK, but only CK1, i want keen4e!

actually, i think this emulator is far more suited to alleycat and sopwith2, maybe impact would be playable

Lemmings and Prince seem like odd choices, arent these cracked versions of commercial titles, i know no one cares thesedays but still.

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[gbjbaanb]

what you want, me old mucka, is DosBox [sourceforge.net]. And then you can have all of 6 Commander Keen episodess. Here's the first one [bestoldgames.net], enjoy.