Hardware booting problem

[Doug Hardie]

I encountered a situation today that I do not understand.  This is a very old i386 PC that does not have a usable CD drive.  The existing drive uses a very funky SCSI connector that I have nothing for.  The system disk is SCSI and there was one additional PATA drive used for additional storage.  The PATA drive failed.  It won't even stick around in /dev for more than a couple minutes after boot and there are lots of messages about bad sectors.  The data is completely backed up and the that drive is over 5 years old.

I removed the old drive and installed a new one.  System will not boot.  It hangs in the BIOS.  Never gets around to installing the SCSI BIOS.  My first guess was there was no boot sector on the SCSI drive.  That seems unusual since my other systems boot off the SCSI drives just fine.  This one used to also before I added the PATA drive.  However, if I put the dead drive back in along with the new one, then it boots.  This also implies that the boot sector was only on the PATA drive.  But the PATA drive is for all intents and purposes dead.  So how is it booting?  Is there any way to look into the SCSI drive and see if there is a boot sector there?

This is more a curiosity item as there are additional failures starting to occur in that computer.  We are going to replace it.  Its around 10 years old.