VAXstation 4000/vlc mouse issue

Antonio Carlini a.carlini at
Tue Jun 1 13:53:47 CDT 2021

On 01/06/2021 17:41, Paul Koning via cctalk wrote:
> It would be interesting to attach a UART to the comm link (4800 bps, RS-232 signal levels) and capture what happens.  It's quite strange to see a system failure caused by pressing a button.  I suppose it could be a bug in the system software mishandling a protocol error on the mouse to system link.  Or perhaps the mouse embedded controller has failed so that pressing the button in question crashes the controller and makes it stop talking to the host.  In that case you'd think that unplugging and replugging the mouse would cure the issue, though.
Years ago I had a VSXXX-AA mouse that stopped a VS3100-76 from powering 
up. Removed the mouse and it was fine. Tried another mouse and it was fine.

I recently re-tested my DEC mice and none exhibited that behaviour, so 
I've no idea where that one has ended up. I couldn't remember whether 
you could hot-swap mice or keyboards (I *think* you could, but I wasn't 
*sure*) so I tested the slow way, with reboots and power-cycles (and a 
long gap to give the VS4000-60 a breather in between!)


Antonio Carlini
antonio at

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