On DOS, NT, etc.
ZP told you correctly. The NT Dos prompt isn't. It's an NT
command prompt with a syntax like DOS and in fact it has
more capabilities than DOS as a command interpreter. Now
(beyond a better command editor) DON'T ask me what, I've
read that but not investigated.
As ZP says also, it provides an environment where most DOS
aps can run, but protects the lower machine functions from
access which DOS permits. So you can't flash the bios or
poke adapter card registers or take over the graphical
interface to run CAD and so on. NT Dos has nothing at
all to do with a separately installed genuine DOS, except
it can boot it, also as ZP said. More particularly,
NT can boot ONE additional OS besides itself, which
can be DOS or something else.
If there's another OS installed before NT, NT does detect
it and arrange to allow it to boot. There are two
things required for this:
The boot sector of the previous OS is saved in the C drive
root directory with the file name BOOTSECT.DOS.
The NT boot.ini file (also in the C: root directory)
gets an entry in its [operating systems] section similar
to
c:\="Previous Version of Windows"
This boot.ini entry makes the string "Previous Version of
Windows" show as an option in the NT boot sequence.
If you select it, NT retires from the scene by jumping
to the saved boot sector c:\bootsect.dos, which then
proceeds to boot whatever OS was installed before NT
was loaded (the OS to which the saved boot sector pertains).
If you've installed NT and then want to install DOS afterwards,
in effect what you have to do is save the NT boot sector,
install DOS, save ITS boot sector in bootsect.dos,
then restore NTs boot sector. Finally, you have to make
an entry in boot.ini so you can select the previous OS.
There is no non-scary way to do this unless you use
a boot manager (I get a bit scared by boot managers, myself
<g>). The way sanctioned by Microsoft, or at
least it's in their documentation somewhere, is to
install DOS over NT, which doesn't hurt NT except
to blow away its boot sector. Then run NT setup from
floppies, select "Repair an Existing NT Install", then
select "Repair Boot" and NT will rebuild its boot
environment, this time setting up to boot DOS.
(BE SURE you have the set of three NT setup
floppies before you try this; they can be created
by NT setup on the CD).
You can also do it by hand with a couple of Resource Kit
tools, Diskprobe and Disksave. Diskprobe runs under
NT and allows you to edit physical disks sector by sector
(view, alter, save to a file, and restore from a file).
Disksave runs under DOS (the real one), and allows you
to save and restore partition boot sectors and the master
boot record.
Here's how to proceed. Incidentally, I'm assuming the
C:\ partition under NT is FAT16. It has to be if you're
going to install DOS there. If it's something else the
procedure would be different, which we'll save for
another day.
1. Prepare by putting diskprobe and disksave on a floppy.
2. Using Diskprobe under NT, save the c: partition boot
sector. Save this file on the floppy with diskprobe and
(most especially) disksave.
3. Install DOS on c: and boot it.
4. With disksave, save the c: partition boot sector to
C:\BOOTSECT.DOS. I would also copy it to the floppy.
4.1. Although not part of this procedure, at this point
I would build a bootable DOS system on floppy, and copy
to it: disksave, diskprobe, the NT and DOS boot sectors,
and the usual list of Prudent Things To Have
On Dos Floppies (from memory, FDISK, CHKDISK, EDIT,
MSCDEX, Dos driver for CDROM, FORMAT, EXPAND, ATTRIB,
XCOPY, and I'm sure I've missed a couple).
5. Again with disksave, restore the NT partition boot sector
to the c: partition.
6. Reboot. This will boot NT.
7. Modify the boot.ini file to contain a C:\="Boot Dos"
entry in the [operating systems] section.
"Boot Dos" will now appear in the NT boot up menu.
As an added bonus, you now have a way to repair the NT
boot sector independent of the NT install. That's one
of the real bonuses of all of this. |
