SCSI Controller Hanging...

Jack Harper harper at
Wed Jan 24 10:33:20 CST 2018

Hello Plamen -

I use the SCSI controller that is built into the MVME177 transition module.

No, when I RESET the system, I just press the 
RESET button on the processor board - usually 
when it is hung with my software.  On this 
system, I only code in 68K assembly and so I do see the "occasional" hang :)

Is the "SCSI reset option" part of the 68K/BUG RESET command?

In my documentation - and I easily may not have 
the latest documentation - I only see RESET 
options to force a COLD or WARM start on hardware RESET.

The documentation that I have also cautions: 
"...may cause the disk controller to be out of 
phase with respect to the disk configuration 
tables in memory", which certainly makes sense.

However, I do not modify any of those tables from system default.

I appreciate your input.


Evergreen, Colorado

At 11:57 AM 1/23/2018, Plamen Mihaylov wrote:
>What SCSI controller are you using - MVME320, 327 or 328 ?
>Do you reset the MVME177 board using RESET 
>command from 177bug> along with SCSI bus reset  option?
>Best regards,
>On Tue, Jan 23, 2018 at 6:33 PM, 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
>Jack Harper, President
>Secure Outcomes Inc
>2942 Evergreen Parkway, Suite 300
>Evergreen, Colorado 80439 USA
><tel:303.670.3750>303.670.3750Â (fax)
>for Product Info.

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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