Synchronous serial Re: E-Mail Formats RE: Future of cctalk/cctech

Peter Coghlan cctalk at
Thu Jun 18 16:39:25 CDT 2020

Paul Koning wrote:
> > On Jun 18, 2020, at 2:14 PM, Peter Coghlan via cctalk <cctalk at classiccmp.or
> >
> > ...
> > As I mentioned in another reply, I have a pair of baseband synchronous mode
> > and were it not for a speed incompatibility between them and the MicroVAX
> > synchronous serial interfaces I have access to, ...
> I'm curious about that.  Synchronous modems supply the bit clock to the
> interface.  So a synchronous interface works at whatever speed the modem
> delivers, so long as it's not too fast for the interface. What are the
> Microvax sync interfaces you have?  DMV?  DUV?  A DMV will work at up to
> 56 kbps.

There is conflicting information about what exactly the interface I have
which is fitted in a MicroVAX 3100 is called.  It looks most likely to be a
DSH32 or a DSH32-B which may amount to the same thing but it could also be
a DST32 which may also amount to the same thing...  Documentation suggests
that the synchronous interface part of a DSH32 (which for added confusion
is referred to as DSH32-S) is DSV11 compatible but limited to a maximum
of 19200 bps.

The modems I have (which were intended for use with 64 kbps lines attached
to Cisco routers) don't have jumpers for clock speeds lower than 48 kbps.


> 	paul

More information about the cctalk mailing list