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1993-10-20
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OS Boot Select Version 2.0 Beta8, October 1993
Copyright (c) 1991, 1992, 1993 Thomas Wolfram
Preliminary Manual
--------------------------------------------------------------
WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING!
THIS IS BETA SOFTWARE. IT'S NOT COMPLETE AND IT'S NOT COMP-
LETLY TESTED. USE IT ON YOUR OWN RISK! BE SURE TO BACKUP
YOUR DISK(S) BEFORE INSTALLING IT!
WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING!
THOMAS WOLFRAM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
EVENT SHALL THOMAS WOLFRAM BE LIABLE FOR ANY SPECIAL, INDIRECT OR
CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
I. INTRODUCTION
II. INSTALLATION
III. HINTS
IV. BUGS
Please read also README.135 from os-bs v1.35. It's in big parts
still valid.
I. INTRODUCTION
---------------
OS Boot Select is a replacement of the ordinary master boot
program. It provides a customizable boot menu with a timeout
and the abiltity to automatically set the active partition
before booting. This avoids boot problems with some UNIX
systems. Unlike the OS/2 2.x boot manager's it only requires
the 512 byte of the master boot sector (sector 0) and some
additional sectors which can be anywhere on the disk (see below!)
but no seperate 1MB partition.
OS Boot Select comes with a installation program running
under DOS.
II. INSTALLATION
----------------
Installation is quite simple. First you must unpack the
archive. This is done by typing:
C:\>osbsBETA.exe
This will create a directory "os-bs".
WARNING!!! At this point having a *tested* bootable DOS
floppy is strongly recommended! Don't continue without!
To recall:
C:\>format a: /s
will do it. Copy then os-bs to the boot floppy!
C:\>cd os-bs
C:\OS-BS>copy osbs20b8.exe a:\
C:\OS-BS>copy os-bs.com a:\
(Os-bs.com is still v1.35.)
OS Boot Select comes with an installation program. To start
it, type:
C:\OS-BS>osbs20b8
...try it. Should I really describe the desktop here?
III. HINTS
----------
III.1 What's new?
-----------------
Os-bs 2.0 is in principle now able to boot from drives in Extended
Partitions and from other disks then the first one, if they are
accessible via the BIOS (function "int 0x13"). E.g. the new SCSI
Controller Adaptec AHA1542C is able to manage more then 2 disks via
the BIOS. Its predecessor 1542B could only manage the first two
disks (ID0 and ID1) without special driver support.
The problem is that almost no operating system is able to boot
straightforward from a second, third, etc. disk (see below).
The booting menu is now more comfortable, also the installation
program.
III.2 Sectors for the os-bs boot loader
---------------------------------------
Apart from the master boot sector os-bs 2.0 needs 4 additional
sectors for its extended functionality. In future versions this
place will be selectable by the user.
Currently os-bs uses WITHOUT ASKING(!) the sectors 2, 3, 4, 5 on
cylinder 0, head 0 on the first disk. On almost all disks I ever
saw these sectors (and the whole first track, except sector 1
which contains the Master Boot Record) are unused. (BTW, the
reason why some boot viruses like this place...).
The first physical partition starts usually on cylinder 0, *head 1*,
sector 1.
So this place will probably stay at least the default place for the
os-bs loader in the future.
If you're not sure whether these sectors are free on your disk
you shouldn't use this beta version!
(To find out whether they are free you could e.g. use the execellent
"diskedit" from Norton Utilities or any other tool which displays
the partition table. If the first physical partition on your
disk starts at cylinder 0, ***head 1***, sector 1, all is ok.
If it starts at cylinder 0, head 0, sector 2 (which is *very*
unusual) don't use this beta version!)
III.3 Why booting from others disks/logical drives almost never
works
---------------------------------------------------------------
This is because the most operating systems are not prepared to
do it.
I would like if there would be a standard booting scheme for
this but there is no one.
Currently os-bs supports a straightforward attempt. It loads
the partition sector (i.e. primary or extended, regardless of
the drive) which contains the entry for the desired system to
0:600h and the boot sector of the system to 0:7C00h.
Then it jumps to it (i.e. to 0:7C00h). The drive number (80h..FFh)
is passed in the AL register and the offset (relativly to segment 0,
i.e. 7BEh + n*16) of the partition table entry of this system in the
SI register of the CPU.
So modify your operating system now for this scheme, system
developers, please! :-)
If you think it's not good enough we can also found a standard
consortium, comitee or something like that. :-)
However, I'll try to implement workarounds for DOS and OS/2 soon
(similar like LILO from Linux).
III.4 Linux/LILO
----------------
Linux is probably the only system in the moment which can be booted
from the second disk/logical drives via os-bs 2.0 but only if you
have a Extended Partition on the first disk. This is because the
LILO boot loader can only be installed in the partition table
sector of the Extended Partition (except from the MBR of course).
To use os-bs you must install LILO in the Extended Partition
sector rather then in the Master Boot Record.
Hence if you create an os-bs menu entry for Linux on the second
disk/logical drive you should use the Extended Partition on the first
disk rather then the Linux boot partition itself. This doesn't apply
of course if you've installed Linux in a primary partition on
the first disk.
Please read the LILO documentation.
III.5. Windows NT
-----------------
Note, this hints here are still based on the march beta version.
Windows NT requires some special action depending how do/did you
install it.
If you've installed NT in a primary partition and there was no
DOS on the disk you can simply add NT to the os-bs boot menu.
(i) If you didn't install NT yet but you plan to do it, and you
have a primary DOS partition I recommend you to "hide" it before
you install NT.
Make a DOS boot floopy! Copy os-bs to it and then run it. Choose
"Edit", then "SysID/ActiveID". Change the partition ID of your
primary DOS partition to a strange one, i.e. "A6". Save it do disk.
Then install NT in it's own primary partition.
Reboot DOS from floppy, re-run os-bs and change the ID back
to old one. Then install the os-bs boot menu with entries for
NT and DOS and the "set-active-id-before-booting" feature of
os-bs enabled.
After that you can boot NT and DOS from the os-bs menu and NT
is even able to access the primary DOS partition.
If you have already installed NT and you have a primary DOS
partition NT did very probably override the DOS boot code
with it's own. Hence if you boot from the DOS partition you'll
boot the NT loader instead DOS. The NT partition itself
contains no boot code and hence you cannot boot directly NT from it
via a os-bs menu entry.
To workaround you can create at least two os-bs boot menu entries
which point to the same partition (the old DOS primary) partition,
one of them labeled "DOS" and one "NT".
Of course this is not very nice and you will always run into
the NT loader to choose really which system to boot.
Currently I know no working way to get rid of the NT loader, except (i).
IV. BUGS
--------
You will notice that there are some os-bs menu entries are disabled,
even "Uninstall". So currently the only way to uninstall os-bs v2.0b8
is "fdisk /mbr", or using os-bs v1.35 (it's "os-bs.com" in the
distribution archive file).
Please mail any hints, questions, bug reports to
Thomas Wolfram
thomas@aeon.in-berlin.de or wolf@prz.tu-berlin.de
Thanks.