Weird problem booting 82

First I must say I don't know why this does not work as you expect. I would expect the same. Now, given this problem, you may still manage to get it working. When using the BIOS to access the disks, there is a parameter that specifies the disk number, and this is specified as 0 for the first floppy, and 0x80 for the first disk. It turns out that the Windows MBR is unable to boot unless the boot disk is 0x80. For this reason, the bios renumbers the disks when you set up the bios to boot off the primary slave disk.

The map commands work by installing in memory a frontend to the bios "int 13h" call, that inspects the register containing the disk number, and if it is, say 0x81, change it to 0x80. (That would be "map (hd1) (hd0)".) I find it surprising that this does not work well for you, but I have also had a computer where this did not work well, and I never understood why. I suspect that there are some other bios calls that also deal with disks, and are not accessed through "int 13h". That could create some confusion.

If you decide to keep the bios booting off the primary slave, you could install grub into the mbr on that disk. Linux will still see the master as hda and the slave as hdb, but grub uses bios calls during boot, and need to be told that the Linux parbreastion is on (hd1), which will now refer to hda. When running grub commands under Linux, Grub accesses the disks through the linux kernel, so Grub needs to guess which is which. With the bios set to boot from the primary slave, Grub does not know that, and will guess wrong. To get this right, you need to create a file called "-boot-grub-device.map" with the right buttociations. The grub.conf or menu.lst file must be changed to reflect what it looks like during boot. The Windows stanza must not point to the mbr but to the appropriate parbreastion. E.g.

rootnoverify (hd0,0) chainloader +1

(The "makeactive" command is not necessary if that parbreastion is always "active" or has the "bootable flag" set in fdisk.) This will make Grub do exactly what the standard Windows MBR code does, load one sector from the parbreastion specified.

-Enrique