Thanks for the reply, Paul.
The problem doesn’t seem to be related to the 1024 cylindar limit since there
are only 128 cylindars on the disk. I did try an installation with and without
BIOS LBA translation enabled. Both installs give the same results at boot time:
Boot Partition 4
Missing Operating System
The drive geometry (reported by the install program) is: 255 heads, 63
sectors/cylindar, 128 cylindars
fdisk shows the partition to be in slot 4, type 77, bootable, start cyl = 0, end
cyl = 126, 127 cylindars, 2040192 blocks, 996 MB.
I like David Gibbs suggestion that the mapping from linear SCSI blocks to
cyl/head/sect is different for the BIOS at boot time versus install time (with
32-bit SCSI driver loaded). I just don’t know how to tell the loader where to
look for the boot image (if its even possible).
Paul Russell wrote:
We are using the Adaptec AHA-2940UW PRO with 8Gig SCSI Drives on QNX4.25
(Note the 3940 didn’t work).
Warning: the cylinders used in the partition must be between 0 and 1023 for
If you have other things on the drive and the QNX Partition’s Cylinders go
beyond 1023, the
drive may not be bootable (DOS and some other OS’s have this limitation - to
be bootable the partition has to be fully in the first 1024 cylinders -
If the QNX4 partition occupies cylinders both <1023 and >1023, it will
probably be bootable in the beginning, but may loose boot support if you
ever redo the boot file.
Clear all partitions, and in the SCSI Controller enable
[Ttranslate/LBA/Mapping] mode so that the to remount the drive with software
remapped cylinders/heads/sectors so that cylinders is <1024. Continue as
At the screen where you select the partition - Press ALT-ENTER to bring
up a menu and select shell. The in the shell run (fdisk /dev/hd0.0) or
(/bin/fdisk /dev/hd0.0) or similar. In the fdisk manually delete any
existing type 77 partition, and then create your own type 77 partition
(usually in position 4) in available cylinders < 1024. The set the partition
as bootable, save, and reboot the computer. When CD gets to that stage again
install to the existing partition.
Prepare an IDE Drive and boot from it, then mount the SCSI drive
manually and configure it up (Fsys.scsi…, fdisk /dev/hdX.0, dinit -h
/dev/hdX.0, mount -p /dev/hdX.0; mount /dev/hdX.0t77 /hdX0), load whatever
you like onto the drive (copy of IDE with custom .boot file), then remove
the IDE, and boot from the SCSI.
Create a small boot partion within the first 1023 cylinders that does
nothing but mount a larger type 78 QNX4 Partition that is allowed to go
beyond cylinder 1023. The larger partition may be setup by install from the
CD to the type 78 partition. Reading will be required…
Edward A. Hildum <> email@example.com> > wrote in message
news:> 3A06ED29.EE370592@mail.arc.nasa.gov> …
My controller is an Adaptec AHA-2940UW, and extended translation (>1G) is
I’m not clear what you mean by a drive mapping disagreement in this case,
since a SCSI disk looks like a linear array of blocks to the controller.
I’ve tried installing to a single partition and multiple partitions with
change in symptoms. QNX always makes partition 4 the boot partition.
Thanks for your response,
David Gibbs wrote:
Edward A. Hildum <> firstname.lastname@example.org> > wrote:
I’ve installed QNX 4.25 from the Dec99 CD onto a 1 Gig SCSI hard disk.
The OS install goes fine, but the boot loader can’t find the OS - it
halts saying “Missing operating system”. What am I missing? The
boots fine from the boot floppy created during the install.
What type of controller do you have?
In the SCSI bios, do you have the >1G drive option enabled?
Missing OS usually means there is a drive mapping disagreement
between the BIOS/OS/Disk controller.