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:
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
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)
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.