Thank you maschoen, I will explain. Yes, I meant QNX4 (multiple OSs) loader.
Installing new empty HDD. Creating and formatting 2GB DOS partition and installing DOS for testing/service purposes. Then installing QNX4 - QNX installer will “see” DOS partition and automatically installs QNX OS loader to be able to boot DOS or QNX4 (choose among them at boot time) and sets QNX partition as active.
[QNX OS loader could be manually re/installed by QNX4s “fdisk /dev/hd0t77” and selecting (L)oader and (S)ave, if the loader was previously removed by rewriting MBR with Standard].
When booting, QNX OS loader writes:
“QNX loader boot partition 1,2 2”
2-QNX4 (partition set as Active)]
and if you do nothing, active (2, QNX4) will continue booting after some seconds.
If you press “1” at that dialog, then DOS (partition 1) will continue booting.
Then if you want to prevent end users (operators) to boot DOS, you can remove QNX loader from MBR (no “Boot partition 1,2 2” dialog at boot time - active partition boots).
In the past I used simple DOS antivirus which had function “Overwrite MBR - replace it with Standard” and QNX loader was gone. PC then booted directly to active (QNX4) partition (without that OS loader dialog).
Now with WinXP (larger than 8GB) partition and “new” QNX4 Suite (no need for having QNX4 boot image under 1024 cylinder) I want to prevent end users from booting Win XP too.
I tried DOSs “fdisk /mbr” from DOS boot floppy (rewriting MBR with standard) but after that QNX4 is not able to boot: “Missing operating system”.
But if I set WinXP partition as active (by the same DOS floppy fdisk), XP boots without any problems.