DEC Mouse replacement

mark at mark at
Fri May 4 02:13:05 CDT 2018

The Linux Kernel has support for DEC VSXXX mouse (as well as LK keyboards), the opposite of what you are interested in.
So the conversion from DEC protocol is well documented.
It would be fairly straightforward with a microcontroller to implement the reverse.


The major issue implementing support for DEC mice under Linux is the requirement for a -12v power rail - clearly this isn't an issue with a modern day replacement (I suspect it is a red-herring anyway for standard mice, just because-12v exists at the DEC connector doesn't mean it is used, possibly it was for digitizers for example).

The DEC mouse protocol is described here:, section C6 onwards.

Regards, Mark.

-----Original Message-----
From: cctalk <cctalk-bounces at> On Behalf Of Bill Degnan via cctalk
Sent: Friday, May 4, 2018 3:06 AM
To: Douglas Taylor <dj.taylor4 at>; General Discussion: On-Topic and Off-Topic Posts <cctalk at>
Subject: Re: DEC Mouse replacement

On Thu, May 3, 2018, 9:38 PM Douglas Taylor via cctalk < cctalk at> wrote:

> I would like to have a couple more DEC Mice for some Vaxestations I 
> have, but they seem to be pretty rare.  At present I only have one 
> mouse and I move it from machine to machine.
> The protocols for the DEC mice and the standard PS/2 mice don't seem 
> to be that much different.
> Is it possible to use an arduino to translate  PS/2 mouse output and 
> then send it to the vaxstation so that will it mimic a classic DEC mouse?

The jack is different, that would be a factor too.


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