Okay, I get the picture.

Do you have the install media for this O/S?

Does the machine have a floppy drive (that works)?
If so, you can make what is known as a "root & boot" set which will facilitate you getting the machine back on its feet if you have a full tape backup.

To create the "root & boot" floppies login as root and run:

Code:

# mkdev fd

which will give you a menu driven interface. Select the options to write out the emergency floppies.

To make a full tape backup capable of disaster recovery you should use cpio NOT tar. (The reason is that tar doesn't backup/restore the device nodes properly in /dev).

Typically:

Code:

 
 # cd /
 # find . -depth -print|cpio -ov -C10240 -K<tape size in K's> /dev/rct0

Yes, you can leave out the -C switch out but it is more efficient to write 10K blocks to tape. The -K should specify the capacity of each tape so that it calls for the next tape if needed. You should also use the -c switch if you want to write in 'portable' format such as knowing you are going to change platforms.

With a 'root & boot' set you can boot from floppy which contains all the commands needed for recovery, the required boot block copies, etc. So you can use the 'divvy' command to lay out a new hard drive and create the filesystems. The 'dd' command to write out boot blocks 0 and 1.
You can then mount your new empty hard disk root filesystem and restore the whole from tape. Also, restore any non-root filesystems.

That is broadly it. Feel free to ask further questions.

There is better SCO knowledge on this forum than mine so, down the line, you might ask moderators to move this thread to the SCO forum proper where it will be more likely to be seen by the right people.

Hope that helps.