Re: terminal server for vax?

Richard wrote:

Looking on ebay I see that there are a variety of products called
'DECserver'. So far they are all terminal servers. Is it safe to
assume this name was only used for terminal servers?

I'd not assume anything about eBay posting, but that's just me.

Is there any
qualitative difference in functionality between the DB25 port style
DECservers and the RJ45 port style DECservers?

I'd tend to stick with DECserver 90-series boxes, or DECserver 700-series boxes, and -- unless I needed modem control -- I'd not worry about the difference between the MMJ connections and the DB25 connections.

And the pinouts and adapter part numbers and other such for the MMJ and DB25 widgets and other common connections are listed in or are referenced in the OpenVMS FAQ.

My motivation here is that I have a collection of vintage serial
terminals. I would like to have a multiplicity of them hooked to a
single machine that could allow some sort of text-based timesharing.

That's what LAT does.

The options I have are:
- PDP 11/03 running RT-11
Seems too underpowered. AFAIK RT-11 just allows one "console"
session and the other serial ports are just treated as output
devices (like to an LA-120).

You can potentially use reverse LAT, and have a terminal server connected "the other way 'round", and have it set up to accept incoming connections. This was a common technique for connection the serial consoles on many of the VAX and Alpha servers. (And any Integrity server that somebody forgot to order the MP card for. :-)

- VAXserver 4000/300
It should be able to handle it, but as you mention its not the
kind of machine that was typically wired up with serial ports
and used as a timesharing machine. You mentioned about the
multi-user license; would the OpenVMS hobbyist license allow
multiple logins?

Off hand, I don't know that. You should be able to tell that with a SHOW LICENSE/CHARGE command; the box should show up as being capable of timesharing, or capable of file and application services. The former or one of the other types of licenses likely indicates that you have or can have full timesharing licenses, while if only the (Type B) F&A license is permitted, that's the usual (and restricted) server license.

Can the DECserver models provide LAT connectivity, or do you need to
get a different box for that? I am under the impression that VMS has
LAT support builtin on the host side.

All of the DIGITAL DECserver models I am aware of provide LAT, and OpenVMS has LAT built in. Very old OpenVMS VAX releases had rather limited LAT support, but anything from about V6.0 forward has reasonably full support.

Newer DECserver terminal servers -- and "newer" being a very relative term here -- can also provide IP connectivity.


I looked at the DECserver 90 manual which is what gave me the idea for
buying some sort of terminal connectivity to my VAX. They mention
installation of software in the manual, but I didn't drill deep enough
to know if this was software installed on the 90 itself or on a host.

Some of the terminal servers require downloadable software.

The DECserver 100, 200 and 250 series, for instance, do require the terminal server's software be downloaded into the box using DECnet MOP.

Don't confuse the fact that the terminal server is registered in the DECnet database for the MOP download with the fact that the terminal server itself does not use DECnet. The maintenance protocols are used for the initial download and (if required) for an upline dump should the box crash (and be configured to upload said dump), but the network protocol used is LAT and is not DECnet.

With OpenVMS V6.2 and later, you can use LANCP to control and to provide any MOP download required for your terminal server, or with that OpenVMS release and with other releases you can use either DECnet Phase IV MOP or DECnet-Plus MOP for that task.

The lower-end DECserver 90 series models might have had this requirement, as well -- the models I have used had built-in firmware.

Is there some sort of host software that must be installed in order
to service these serial ports via the terminal server as distinct login
sessions? I am not familiar with how VMS handles this and while my VAX
has OpenVMS installed, I am a complete newbie to VMS :-).

OpenVMS has the LAT part, and once the terminal server is bootstrapped it too has LAT capabilities. What the terminal server requires depends on which terminal server is chosen.

I know in *nix they did something like associate the login program
with the serial device. So you would get a login by pressing RETURN
on the terminal.

On OpenVMS, unsolicited input on an unallocated terminal line fires up the LOGINOUT image.

If you connect "odd" devices onto a serial line, and particularly devices that are likely to generate what could be construed as unsolicited input up the serial line as the device conducts its normal business, you will likely want to disable this automatic login mechanism using the techniques discussed in the OpenVMS FAQ.

I vaguely recall using a LAT server in 1989 to which
you had to request connection to a particular host and then you got a
telnet type login session. ISTR that you could have the terminal
connected to multiple hosts via the LAT and could switch back and
forth.

You can have the terminal directly connect to a specified LAT service, or you can have the terminal allowed to choose which service will be the target. This is a configuration option in the terminal server, and it can be set up on the particular serial port of the terminal server.

Was specific terminal support required for this to work?

No.

If you wanted multiple parallel sessions for one terminal on one serial line, then you did need the SSU software and/or support in the terminal server, and you did need a terminal with SSU support. This as distinct from disconnecting from one host and reconnecting to another -- SSU and an SSU-capable terminal provided a form of a serial line mux.

I only did this with a VT220, so I don't know if it was exploiting
something that was present only in DEC terminals.

For standard LAT operations and connections, it was not.

Various of the DIGITAL System and Options Catalog (SOC) entries for many of these old systems remain available in the left navigation at the URL <http://www.hp.com/go/productbulletin/>.

I didn't find anything there on the DECserver 90, 700. Do you know
specifically if its there and I just missed it?

Those are likely too new. The DECserver product line was sold off to the organization that eventually became the DNPG (Digital Network Products Group) folks some eons ago. You'll only find the older of the DECserver boxes listed in the SOC. The folks over at <http://www.dnpg.com/> likely have details on the newer giblets.



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Relevant Pages

  • Re: terminal server for vax?
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