[HECnet] More NRT

[Johnny Billquist]

Hi. Even more things then...

On 2020-05-05 07:14, Thomas DeBellis wrote:
> What's fun about the Tops-20 NRT client (SETHOST) is that it doesn't do 
> much aside from parsing for an escape character and node name.  It 
> builds a connection string and checks to make sure the remote system is 
> either a 10 or a 20.  Then it twiddles a few things on the terminal (a 
> few more if you're running my changes to handle page mode).  Finally, 
> and this is the cool part, it issues an MTOPR% to directly connect the 
> local user's terminal to the open DECnet connection (port 23).

Makes sense. I think essentially all OS specific remote terminal 
protocols used object 23. The RSX one certainly does. The client should 
check that the remote system then is of the expected type, or else 
things will (obviously) not work well.

> Thereafter, the client does nothing until the interrupt character is 
> typed or the connection is broken.  So response can be pretty snappy 
> because you are never running in user space; no context switching.  The 
> CTERM client on the other hand is reading and writing data and otherwise 
> handling the specifics of the protocol in user space.  So, more overhead 
> and more context switching.
> 
> As an experiment, I removed the checks for Tops-10 and Tops-20 and tried 
> connecting to a few hosts on HECnet.
> 
>   * Tops-20; TOMMYT and TWENEX worked (of course)
>   * Tops-10; VENTI worked
>   * RSX-11+; MIM accepted the connection and broke it as soon as I
>     started typing.

Probably because the RSX server expects the RSX specific remote terminal 
protocol, which most likely do not match the 36-bit one.

>   * VMS; LEGATO accepted the connection and broke it as soon as I
>     started typing.

VMS might have something RSX-like going on there.
I can't really tell, as VMS don't seem to support showing known objects.

>   * RSTS; TRON accepted the connection and then did nothing.  It never
>     broke the connection, but never displayed any banner or anything
>     else.  It appeared hung.

RSTS is probably using object 23 for the RSTS/E specific terminal 
protocol, and that server is apparently not cooperating with your 
SETHOST. :-)

> So it would appear that NRT servers only exist on the 36 bit line.  
> Perhaps it's possible to configure the service for other platforms?

It's a bit more complicated than that, but I hope you have a better idea 
now...

> The first few RSTS systems I tried didn't appear to be online; MEZZO, 
> PLUTO, RSTSE and BITXOT.  The few Windows systems I checked didn't 
> appear to be online, either; WXP, MISSY, KIBBEH and WATAN. I'm not sure 
> if that means they refused the connection attempt outright.

WXP is definitely not online right now.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol