[HECnet] Connecting an HP Itanium BL860c to HECNET... without ethernet

[Thomas DeBellis]

Those names almost sound like they want to be familiar, but not quite.  
What I recall for a DN20 was that, in terms of communication, MCB only 
had two speeds.

  * A 'fast' interface could do 56 KBid, synchronous.  I /think/ that
    part was called a "KMC".  It may have had some sort of embedded
    microprocessor on it, but I don't recall what kind of operations it
    performed.
  * A 'slow' interface could do up to 9.6 KBid (I think).  I can't quite
    remember what it was called.  Maybe a DUP-11?  I might be getting
    that mixed up with the RSX20F front end, which had single line
    interfaces that I think were called DL's.

I don't recall that MCB could do asynchronous communications, but I 
don't remember that it did.  I can't remember how we connected distant 
systems (CMU, Case Western and Stevens) when we were first building 
CCnet.  I had thought that we were using synchronous modems, but I 
wouldn't swear to it.

There was a bit of an argument when we finally got Ethernet (and the CI) 
and DECnet IV that most of the DN20's should be disconnected and 
removed,  This was to free up space in our perennially cramped machine 
room, but it would have meant less heat, electricity and maybe less 
maintenance $$$.  The overall head of Tops-20 systems programming 
decided to play it conservatively and keep them, 'just in case'.  I 
think if DEC had not walked away from the 36 bit market, they probably 
would have eventually been pitched.

We had a Pro, but this was largely to port Kermit to it.  I think 
Stevens went with Pro's in a rather large way, but I don't remember what 
they ran.
> ------------------------------------------------------------------------
> On 12/10/21 3:36 PM, Paul Koning wrote:
>
> The mainstream comm link before Ethernet was the DMC-11 or DMR-11.  Async DDCMP is a low cost alternative (with lower performance).  You'd tend to find it in embedded applications, which is why it's a key part of RSX.  And it appears in devices like the VT71 typesetting terminal.
> RSTS/E did not do async DDCMP for a long time; I added it at some point to get DECnet onto the Pro.  That was unofficial; in V10.1 it became part of the regular release but even there it is a bit clunky and not quite complete.  But it's enough that you can get DECnet/E to use a terminal line.
>
> 	paul
>> ------------------------------------------------------------------------
>> On Dec 10, 2021, at 3:29 PM, Thomas DeBellis<tommytimesharing at gmail.com>  wrote:
>>
>> I know VMS at least did some kind of line.  Columbia's chemistry department got a VAX before the campus Ethernet existed, so that wouldn't have been an option.
>>
>> However, I can't remember whether it was a synchronous or asynchronous connection; only that the 'wire' went into one of our DN20's (I think CU20B).  I think the 'wire' had modems on both sides, but I can't remember what those were, either.
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