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<p>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).</p>
<p>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.</p>
<p>As an experiment, I removed the checks for Tops-10 and Tops-20
and tried connecting to a few hosts on HECnet.<br>
</p>
<ul>
<li>Tops-20; TOMMYT and TWENEX worked (of course)</li>
<li>Tops-10; VENTI worked<br>
</li>
<li>RSX-11+; MIM accepted the connection and broke it as soon as I
started typing. </li>
<li>VMS; LEGATO accepted the connection and broke it as soon as I
started typing.</li>
<li>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.<br>
</li>
</ul>
<p>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?</p>
<p>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.</p>
<p><br>
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