I'm splitting this into a separate topic since it may contain information useful to many people. This is a long post since I'm not sure I'm even focusing on the right symptoms and maybe someone can point out something that I've not thought about. What I'm most curious to discover is why changing things on the SCSI buss would cause the EIII to be unable to load the 'boot OS'. Is it possible that the SCSI controller is worn out and, when the environment isn't just right, the result is it blasts the CPU with garbage preventing normal operation? Read below to learn what I know
I've just bought my first EIII keyboard and, while it does have some problems, it will work well enough on the workbench for me to get some enjoyment out of it. In order to get it ready for real studio work I've gathered a few different SCSI storage options including a neat little SCSI->IDE->CF CARD adapter from scsiforsamplers.com. Although this particular bridge hasn't been tested with an EIII, it has been used with an EIIIx which uses the same SCSI controller chip (5380).
I started by making a backup of the OS from the internal HD to a floppy disk so I can save the hard drive from wear and tear as I troubleshoot the system.. this is where I found my first unexpected event! After making a copy of the OS and testing that it worked I unplugged both the power and 50-pin SCSI cable from the HD and attempted to power the system up... what I got was a blank* screen and no signs of life!
Wanting to be sure I didn't somehow just kill my EIII, I plugged the power and SCSI cable back into the HD and powered up again, success! It booted up and I loaded a bank from the HD to my relief!
On a whim I decided to only unplug the power from the HD and leave the SCSI cable in, I can't easily explain why but this worked and the EIII will power up and boot from the floppy drive as long as the SCSI cable in connected to the hard drive
My assumption at this point is that this has everything to do with SCSI termination.. but it's just a guess.
Now, at this point there is probably enough entropy in the system that I should just quit.. but my urge to tinker is too strong!
Since the system seemed to be working well booting from the floppy I decided to use the SCSI cable leading to the external SCSI connector to hook up the SCSI->IDE adapter. The results were the same as having the HD cable disconnected, a blank* screen
even when I removed power from the adapter (leaving only the scsi cable connected to it) the result was the same.. something I find very confusing!
Thinking that maybe there was a problem with the SCSI cable running to the external port I disconnected the cable from the HD and tried that one, same result. Boo.
Lastly I decided to try with a SCSI Zip drive to see what happened. Using the SCSI cable for the external connector the system powers up and searches for a drive, but doesn't identify any SCSI drives and doesn't boot from the floppy drive** :-/
At this point it was getting late so I retired to the couch to read the service manual. If I've read the manual correctly, the way the SCSI connectors are placed on the main CPU board means that the EIII itself is physically in the *middle* of the scsi chain *and* it has terminators.. something which isn't exactly ideal, no?
I also found that both the SCSI-IDE adapter and Zip drive use active termination.. but honestly I don't know much about what that means
They both have a jumper to disable the termination but this did not make a difference. I've also tried just about every permutation of SCSI ID's and checked that the EIII is set to be device 0.
*the 'blank' screen actually appeared to have some very faint garbled lines being displayed, not unlike what one might see if an OS was attempting to do something but was constantly interrupted at a fast speed.. again just a guess.
** I also found that if the floppy disk with the OS on it has been damaged or corrupted it may not be easy to tell, the EIII will appear to just skip past reading the drive leaving you with the impression that it didn't even try to read the disk.
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