Early terminal server model?

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Galen

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Jun 13, 2020, 10:56:25 AM6/13/20
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What was the early pre-DECserver 100 terminal server called, that came in a large tabletop box (maybe also rack mountable)? It used line cards each of which supported two serial ports, using DB-25 connectors.

I think there may also have been a multi-line speech synthesizer using the same basic hardware platform.

Did it use an LSI-11 processor?

Stephen Hoffman

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Jun 16, 2020, 11:32:21 PM6/16/20
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The boxes you're probably recalling were the DEMSA series DEC
MicroServer boxes, and were built with one of the PDP-11 family
processors—I don't recall which CPU.

The DECtalk III DTC03 rackmount used a variation of the DF100 modem
box, did not use PDP-11 processors, and was unrelated to DEMSA /
MicroServer.

DECtalk I DTC01 used a VT240 system unit box. Didn't use PDP-11
processors, and unrelated to DEMSA / MicroServer.

Yes, a PDP-11 could send commands to a DECtalk. But DECtalk didn't
depend on PDP-11 systems nor software.

DECvoice DTC04, DTC05, and DTCN5 were Q-bus boards, built on OpenVMS
VAX on MicroVAX and VAX 4000 series, and also unrelated to DEMSA /
MicroServer.


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Pure Personal Opinion | HoffmanLabs LLC

Galen

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Jun 20, 2020, 8:41:00 PM6/20/20
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I found out what it was: there was a terminal server version of the DECSA Ethernet Communications Server.

Quoting Wikipedia:
“The DECSA communications server was a communications platform developed by DEC based on a PDP-11/24, with the provision for user installable I/O cards including asynchronous and synchronous modules. This product was used as one of the earliest commercial platforms upon which networking products could be built, including X.25 gateways, SNA gateways, routers, and terminal servers.“

Stephen Hoffman

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Jun 21, 2020, 5:37:28 PM6/21/20
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On 2020-06-21 00:40:59 +0000, Galen said:

> I found out what it was: there was a terminal server version of the
> DECSA Ethernet Communications Server.

That was also the DEMSA platform, AFAIK. The LED segments would tell
you want was loaded into the particular MicroServer box.

Galen Tackett

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Jul 8, 2020, 11:31:08 AM7/8/20
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On Saturday, June 13, 2020 at 10:56:25 AM UTC-4, Galen Tackett wrote:
> What was the early pre-DECserver 100 terminal server called, that came in a large tabletop box (maybe also rack mountable)? It used line cards each of which supported two serial ports, using DB-25 connectors.

I found some material on the 32 port tabletop terminal server that I was referring to. It was the DECSA Communications Serve, definitely not the same thing as a DEMSA.

Quoting from "Communications Options Minireference Manual", EK-CMIV5-RM-005, archived at:

http://www.bitsavers.org/pdf/dec/comm/EK-CMIV5-RM-005_Communications_Options_Minireference_Manual_Vol5_Aug88.pdf

<quote>
DECSA Communications Server Hardware Components
The following hardware components make up the DECSA communications server.
• PDP-ll/24 processor
• Memory module (512K bytes or 1 M byte)
• DEUNA Ethernet to UNIBUS adaptor
• Console/bootstrap/terminator (CBT)
• Protocol assist modules (PAM) set
• Line cards (see the following table) [SUMMARIZED BELOW -- Galen]
• H7200 and H7211 power supply modules
</quote>

<quote>
DECSA Communications Server Software Components
The following software components are included with any DECSA configuration.
• RSX-llS operating system • NS: QIO$ interface (logical link facility)
• NX: QIO$ interface (direct line access facility)
• System level interface
• Initialization task
• PAM device driver
• DEUNA device driver
• Network management
• Down-line load/up-line dump across the Ethernet
• Remote console support (console carrier only)
• Loadable diagnostic image (LDI)
</quote>

The manual describes three types of line cards:
• DCSAX-LA, single line synchronous RS-232 module
• DCSAX-LB, single line V.35 module
• DCSAX-LC, dual line asynchronous RS-232 module

With additional software listed in the manual, the DECSA could also be used as a DECnet router.

I have a vague recollection that there was also a single line Asynchronous RS-232 module, or perhaps, the DCSAX-LA was capable of both synchronous and asynchronous operation.

Figure 4 on page DECSA-11 includes an illustration showing what looks like a DECSA-DA.

We had a lot of problems with the DCSAX-LC modules. which I believe we referred to as "line cards". Fortunately these could be re-seated or swapped "hot"; and I believe our DEC Field Service engineer kept a couple of "unofficially requisitioned" spare line cards available in his on-site office. (We didn't officially have on-site support, but he and the other security-cleared FSE's kept a semi-regular schedule nevertheless.)

Some of the line card problems may have been due to line noise on cabling that our own communications tech shop had rapidly fabricated in-house.

Also, though I have no evidence at this point, I do believe Digital sold a multi-line telephone response system that may have used the same chassis and processor but wasn't called a DECSA. I hope to turn up some information on that.
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