Can You Boot Windows (and Other OSes) Using CD-RWs? 26
CTho9305 asks: "I know you can make bootable CD-R/RWs that work fine to get you running DOS (well, Microsoft will call it Windows without the GUI, but I'll call it DOS). And I know you can boot linux, and even run X. However, that only works because these things can run fine from read-only media. Since a CD-RW could theoretically be mounted read-write under linux, I bet its possible (if it hasn't alread been done) to write a kernel module to boot from a CD-RW with it mounted read/write. What I'm really interested in is booting Windows (9x), which requires read-write media. What would be required? Would a DOS driver suffice? Does such a piece of code exist somewhere?" Such an ability would make it easier for novice users to try other alternative operating systems. Is it likely that BIOS makers will support this ability in the future? What can we do to make this happen?
Re:Connectix (Score:1)
I actually got this to work... (Score:1)
The best part was when I booted the cd on a slightly different GX150, and it "installed" some drivers, then asked me to reboot to activate the changes. "That's odd, this screen keeps popping up..." lol.
-Ryan
Bootable Linux for games. (Score:1)
All email messages are forwarded to
(Seriously they are, I'm not just saying that)
Re:...more... (Score:1)
Re:Not so fast boy. (Score:1)
Re:I actually got this to work... (Score:1)
Re:Booting Windows from RAM (Score:1)
Trimming Windows down to 50 meg? (Score:1)
I'll stick with a Windows Zip Rescue disk. (Score:1)
Re:Windows _can_ boot from CD (Score:2)
Re:CD-RW mounted read/write? (Score:2)
treat the CDR/CDRW as if it's just another
(slow) drive. But you need special software
to be able to read these packet-written
CD's. (Do they use UDF?)
Perhaps you could get away with this;
maybe you need to have two sessions on the
disc as a hybrid ISO/UDF since it would be
difficult to get windows booting from
a packer-written CD before the driver is loaded.
...more... (Score:2)
- you probably can't directly boot windows from a CDROM, because it doesn't like read-only boot volumes
- you *might* be able to copy the windows directory into the ram disk in AUTOEXEC.BAT, but I dunno if subst works in DOS.
- you might also need to disable the IDE controllers in device manager so windows runs in "msdos compatibility mode", otherwise when the IDE drivers start up, they'll try to reassign C: to the hard drive instead of the RAM drive
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Re:CD-RW mounted read/write? (Score:2)
Anyway, if you're looking for some removable, bootable media, look into USB hard drives, zip drives, ls120, etc.
ÕÕ
OT: MacOS from CD-R (Score:2)
Not so fast boy. (Score:2)
Another catch is that it would require some read/write caching since a CD-RW drive isn't quite suited for writing 512-byte blocks.
There's also the need for a steady data stream when writing. Operating systems are meant to run off a hard drive, which doesn't really care how fast the data arrives in the buffer, as long as it gets there. CD recording software uses strict timing and big buffers in order to maintain a steady flow, often giving high priority to the buffering thread. This is bound to give trouble, especially during the boot sequence.
#3 is that most operating systems rely on fast disk access; for example, Windows peeks inside each executable file in a folder to grab its icon. Since CD-Rom accesses are much slower than a hard drive, browsing through a file tree would be very slow and annoying. Windows just wasn't designed for slow data rates. Linux however (and to a certain extent, X) would probably shine in this area since it's been built with compactness in mind from day one.
There are surely more obstacles, I just have better things to do than think about them.
Re:Not so fast boy. (Score:2)
If it does, I've never done anything to enable it. The drive itself supposedly buffers what it needs and simply stops if it runs out.
Re:Not so fast boy. (Score:2)
Some of the new drives like the Plextor 12/10/32A employ 'burn-proof' technology that prevents underrun problems. The drive stops and then starts up again if it runs out of data. I haven't made a coaster since I got mine.
Re:CD-RW mounted read/write? (Score:2)
Windows _can_ boot from CD (Score:3)
German magazine c't had an article about doing this. They made Windows boot from CD flawless. I'm currently looking if i can locate this article, but i fear it isn't online.
Re:Windows _can_ boot from CD (Score:3)
But be warned, the article is in german, so you will need babelfish or better knowledge of german.
HTH.
Yes/No (Score:3)
Creating a RAM drive earlier on and writing to that, and forcing a flush of that to CD-RW during shutdown may be workable.
Windows isn't designed nicely for that though.
Atleast Unix can be tailored for such an environment, as well BeOS is -excelent- in that scenario. They used to sell a demo disc that was designed that way. (only allowed sasving to floppy.). It was a bit slow in accessing the drive though, CD-ROM drives are not good at random access. They are much, much better at large data transfers. (Even on the newer drives random access sucks compared to a hd).
CD-RW mounted read/write? (Score:3)
CD-R(W)s use track or disk based writing, not random access, inode type writing. I don't think you can tell a CD-RW drive to write a block of data to some arbitrary location on the disc.
Now, there isn't much that is impossible, but I think this would take a VERY complicated (and VERY badly performing) abstraction layer, and would be impractical.
Anyone know enough about this to confirm or deny?
-Peter
Re:Windows _can_ boot from CD (Score:4)
You can view it here [heise.de] without having to pay.
Gareth
Connectix (Score:4)
If the objective is to let users try alternative operating systems, consider using the new Connectix [connectix.com] Virtual PC for Windows [connectix.com]. It allows you to install another OS (DOS, Linux, BeOS, etc.) under Windows, where you can try it out just as though it were the native OS. Connectix is offering a free trial download that will work thru July 1.
Booting Windows from RAM (Score:5)
First, there are numerous utilities out there to create RAM disks... device drivers you can put in CONFIG.SYS to give you a drive letter which exists in RAM. Now, the only one I could find was limited to 32 megs. Not enough space? Bah! I installed Windows 95 (the original version) on the hard drive, and was able to delete unnecessary files (help files, etc) to trim the windows directory down to about 25 megs. Also had to disable virtual memory, but I had enough left over RAM that it didn't really matter.
Now, there are a few tricks you need to know to get Windows to boot out of a RAM disk. First, you need to 'subst' command, which lets you raassign drive letters to other directories. For example:
subst x: c:\xdrive
Will let you access c:\xdrive as drive X:. The cool thing is you can reasign existing drive letters:
subst a: c:\floppy
So now A: is just a "symlink" to c:\floppy
Also, you need to know how to do a soft reboot of Windows. If you hold down "shift" when hitting the OK button in the restart dialog, windows will restart but not actualy reboot the computer - so the contents of your RAM disk will stay around. This is basically what happens when you have windows run in "MSDOS mode"... it does a soft restart to a DOS prompt, then when you type exit it restarts Windows without a reboot. So, you can just make a shortcut to an empty batch file, set it run in MSDOS mode, and when you run the shortcut, Windows will do a soft restart.
So, all you need to is write a batch file to run at startup which does the following:
1) copy the Windows directory into you RAM disk R:
2) delete this batch file from the RAM disk
3) subst c: r:\
4) do a soft restart
Now, when you boot your minimal Windows from the hard drive, it will copy itself to RAM, switch the C: drive to the RAM drive, and soft restart itself from the RAM disk. It takes about 2-3 seconds for Windows to do a complete soft restart.
Yoy might be able to do the same thing from a CDROM.
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Here you go (Score:5)
Regular backups often only offer a false feeling of security: After a system crash Windows frequently doesn't even start up anymore, and this puts the restore program out of reach, too. Therefore, a bootable and virus-proof Windows installation on CD ROM should really be found in every well-stocked emergency kit.
'To start Windows 95 or 98 in GUI mode, it must be installed on a writeable medium. You cannot start Windows from CD.' Similar statements have been published in various PC magazines, and c't has said it, too. The time has come to revise this statement.
The reason for this assumption lies in the fact that Windows spits out masses of error messages when unable to access the registry during startup. However, this is essentially only cosmetic: If you can live with it, Windows 9x can indeed be started from a CD ROM. This article will deal with how to eliminate the error messages and optimize CD ROM booting.
Have fun!
-Pat