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.