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

Antonio Carlini a.carlini at
Thu Jun 18 16:47:18 CDT 2020

On 18/06/2020 14:06, Peter Coghlan via cctalk wrote:
> I have found the whole thing very confusing too.  My suspicion was also
> that they were pretty much the same thing but the DST32 had exernal
> connectors suitable for mounting in a MicroVAX 2000 while the DST32 had
> external connectors that could be mounted in a MicroVAX 3100. That is,
> until I also came across the preliminary version of EK-283AA-AD-001
> which threw cold water on that theory.  Unless it was originally called
> the DSH32 and then renamed to DST32 for the MicroVAX 2000 or something...

I expect that the uVAX 2000 interface was around well before the uVAX 
3100 one. I suspect that the docs was wrong or that something got 
renamed at some stage. If I ever frind my notebooks from the time I can 
take a look.

> The console code in one of my MicroVAX 3100 machines shows this:
>>>> test 50
> KA41-D  V1.0
> [snip]
>   DSH32-A  00FF.0001  V1.0
>   DSH32-S  0000.0001  V3.0
>   NI       0000.0001
> Yet in VAX/VMS 7.3, I see this:
> OpenVMS (TM) VAX System analyzer
> SDA> show dev zsa0
> I/O data structures
> -------------------
> ZSA0                                    ZS_DST32          UCB address: 
> 814EAA40
> [snip]

Wonderfully confusing :-)

> I was hoping to use VAX WANDD but I ended up having to install DECnet OSI
> on VMS 7.3.  Perhaps if I dig up an earlier VMS version, I can avoid 
> using
> DECnet OSI?

If you further along it got renamed to DECnet-Plus ... would that help :-)

I don't know when Phase IV support stopped for WANDD. DECnet-VAX 
Extensions went out in the V5.4-3 timeframe IIRC. Certainly for a while 
you have a choice and were not required to run DECnet/OSI. In fact the 
only reason that DECnet-VAX Extensions shipped was (iirc) that PSI/WANDD 
was ready and DECnet/OSI wasn't.

Anyway, pre VMS V6.0 I'm sure you can just pull the latest contemporary 
WANDD kit off a VMS CD and you'll be fine.

> I have two boards in two MicroVAX 3100 machines.  Each board has one
> Synchronous serial port (50 pin D connector) and eight asynchronous
> terminal lines (36 pin Centronics connector).  To add further confusion,
> I have a third MicroVAX 3100 which has the 50 pin and 36 pin external
> connectors on the back but no actual DSH32/DHT32 board inside!
> I also have the following cables:
> 1   BC19C Rev B1  50 pin D (female) to 13/15 pin D (male) X.21
> 1   BC19D Rev B   50 pin D (female) to 16/25 pin D (male) V.24
> 1   BC19F Rev B   50 pin D (female) to 17/34 pin "square" thing (male) 
> V.35
> 1   BC19V         50 pin D (female) to 16/25 pin D (male) V.24

On the synch side the idea was to get away from having a set of (often 
different) cables for each interface. Instead everything had the same 
50-pin connector and then you picked the appropriate cable for V.25 or 
X.21 or whatever you needed. My DST32 has such a connector, as does your 
DSH32. I expect that the DSV-11 also is the same. DECnis certainly is.

> and I also have two Nokia DS 60100 baseband modems, one with a V.35
> interface card and one with an X.21 interface card.  When I hook up the
> former with the BC19F cable, I can get the lights on the modem to react
> when I try to access ZSA0: on the MicroVAX.  However, I can't get any
> reaction when I use the BC19C cable with the latter even when I jumper
> the modem to take account of the fewer signals available in X.21. It
> may be that the BC19C is meant for something other than the DSH/T32...

I don't remember the cable part numbers (although they will be in the 
manuals) but if it plugs into the 50-pin connector then it should work.

> Anyway, this whole line of attack is fairly academic as the modems can
> only do 48kbps - 160kbps and the maximum for the DSH/T32 seems to be
> 19200bps.

I'd be surprised if they don't work at up to 56k at least. Maybe not 64k 
(I remember the DSV11 firmware engineer telling my that some extra work 
had to be done to get one of the DSV11 modes to work properly at 64k 
even in pathological cases, so maybe other, lower-end interfaces didn't 
get the same love).

Above 64k would not have been a normal use case back in the day - I 
don't have any data handy to check what should work though.


Antonio Carlini
antonio at

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