SCSI Controller Hanging...

Jack Harper harper at
Tue Jan 23 11:06:54 CST 2018

Hello Bill -

Yes, there are two 4GB (32-bit addressing) SCSI 
drives on the system and they do have different drive numbers.

I will double check the SCSI termination resistor things.

Motorola documentation is very sparse on this - 
"attach the termination resistor" - nothing on 
exactly where or what the resistor thing looks like.

I am far stronger in software than hardware.

I appreciate the adive.


Evergreen, Colorado

At 09:47 AM 1/23/2018, william degnan wrote:

>On Tue, Jan 23, 2018 at 11:33 AM, Jack Harper 
>via cctalk <<mailto:cctalk at>cctalk at> wrote:
>Greetings to the List from the Snowy Rocky Mountains.
>Beautiful clear sunny day here at +9F :)
>The SCSI controller on the 68K development 
>system (VMEbus) that I have cobbled together 
>occasionally hangs after I reset one of the 
>processor boards (there are four MVME177-005 68060 boards in the VME rack).
>The hang then happens when my software touches 
>the SCSI drives via the ROM'd 68K/Bug I/O 
>primitives and the hang will not go away even 
>after another reset until I cycle power.
>I have never before dealt with SCSI as a 
>programmer - does this sound like something is configured incorrectly?
>There is not much to configure.
>I point out that I am not certain that I have 
>the termination resistors correct.
>I appreciate any advice.
>Evergreen Colorado
>Yes, two things that I'd be checking
>1) Make sure all drives are assigned a different number
>2) Make sure you have termination somewhere.
>Depending on the OS there are commands to 
>display the scsi devices attached, as the OS sees them.

Jack Harper, President
Secure Outcomes Inc
2942 Evergreen Parkway, Suite 300
Evergreen, Colorado 80439 USA

303.670.3750 (fax) for Product Info. 

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