Ron Spruell schreef:
> Jim I understand what you mean by a virtual machine because I know what
> virtual memory is as per Microsoft but for me making a virtual would be just
> as hard as making Free Dos run. I would much rather be able to run FreeDos
A virtual machine as ment here is often also called an Emulator (they
exist for game consoles as well).
some PC emulators are Bochs, QEMU, VirtualPC, VMware.
> from a DVD or CD since I can boot from either. I have my system set to
> search for a bootable DVD or CD or Floppy then go to the hard drive. I
> changed this when I found out about FreeDos a couple of weeks ago. If it
> will boot from a CD or DVD I can burn either one with an ISO image file I
> can do that. That way I know if I boot from either all I have to do to get
> my system back like it's suppose to be is remove the CD or DVD and re-boot.
The only dangerous tool from a LiveCD (CD which boots FreeDOS from a
fake diskette, then loads CDROM drivers to get access to the remainder
of the CD/DVD beyond the initial 1.44MB) is Fdisk as it can change/ruin
the master boot record (MBR), which contains information about your
FreeDOS can only access FAT filesystems, not NTFS for example which
Windows uses nowadays almost exclusively.
Fixing MBR issues is quite nicely done with a free tool called TESTDISK
(I recovered 36GB of music with it..accidentally deleted wrong
disk/partition during a Windows 2000 installation a while ago)
In an emulator no single action can harm your harddisk contents nor
current Windows installation.
> 2. when booting what files does it boot and where or the files located like
> Autoexec.bat config.sys and so on and are these the only ones FreeDos uses
> are there more.
A LiveCD contains a bootloader. Nowadays that's an operating system's
own bootloader (Windows, ReactOS) or an indirect bootloader
(GRUB, ISOLINUX). Isolinux is used most on various Linux distributions,
and also for FreeDOS. Isolinux loads a fake 1.44MB floppy through a
driver called MEMDISK, and fills this 1.44MB with the contents of a
floppy disk image file we've called FDBOOT.IMG. This imagefile contains
the contents you'd also need for loading up a real DOS diskette..a
KERNEL (kernel.sys), a SHELL (command.com), driver loading file
CONFIG.SYS (yes also using this name in FreeDOS though FDCONFIG.SYS is
also a valid name) and a startup scriptfile (AUTOEXEC.BAT or whatever
file the "SHELL=" line in config.sys might refer to)
customising the boot image part is no easy job, and an emulator is best
used. Basicly you load FDBOOT.IMG with for example WinImage, convert to
1.44MB format if needed, then write it to a real diskette. Next, open
the Config.sys and autoexec.bat files, and adjust them. Save the files
to disk. Next, open WinImage again, read in the diskette and save the
contents to FDBOOT.IMG again (usually in the ISOLINUX directory).
Finally, you'd have to create a new bootable CD/DVD using MKISOFS with a
lot of fancy parameters/options.
Blair Campbell might have some scripts to do all of this stuff, as well
as Jeremy Davis maybe. The most fancy option ofcourse would be to have a
LiveCD, and some temporary storage somewhere. You'd boot up the LiveCD
then, write the contents to the temporary storage, modify the contents,
and recreate the ISO file.
Writing CD/DVD from DOS is a challenge though, as I know of no suitable
single tool (they tend to need some non-free driver. For example
CDRECORD needs an ASPI driver that supports writing to the device).
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