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I don't have time to dig up the details. But TOPS-10/20 definitely
supported the CI. It turned out not to be used much since IIRC
despite the high wire speed, thruput was better on the NI. But the
rationale was something like if you had CI connectivity for storage,
and an NI (ethernet) issue, you had to have a means of managing the
other cluster nodes. So DECnet of CI ensured you could set host, do
task-task; whatever.<br>
<br>
For some evidence, look at ntman.mac:<br>
<pre style="font-family: monospace; font-size: medium; background-color: rgb(238, 238, 238); padding: 1em; text-align: left; border: 2px solid black; white-space: pre; color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px;">TABSR1: TXNN T1,<.NTLIN&.NTCKT> ;Is it a LINE or a CIRCUIT?
JRST TABSR2 ;No, don't bother checking Line type
LOAD T2,NXLTY,+NMXVAR ;Get the Line type
MOVE T2,[NTD.D ;Bit indicating DTE
NTD.K ; KDP
NTD.P ; DDP
NTD.C ; CI
NTD.N ; NI
NTD.R]-1(T2) ; DMR
TDNN T2,NT.DEV(NT) ;Does this Parameter apply to this Line Type?
</pre>
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<pre style="font-family: monospace; font-size: medium; background-color: rgb(238, 238, 238); padding: 1em; text-align: left; border: 2px solid black; white-space: pre; color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px;">NMXN23: STOR T1,LIDEV,+P2 ;STORE IN CIRCUIT ID WE ARE BUILDING
CALL NMXN28 ;GET A NUMBER FROM THE STRING
STOR T1,LIKON,+P2 ;STORE AS KONTROLLER NUMBER IN CIRCUIT ID
CALL NMXN28 ;GET THE NEXT NUMBER FROM THE STRING
STOR T1,LIUNI,+P2 ;SAVE UNIT NUMBER
CALL NMXN28 ;GET NEXT NUMBER (IF ANY)
STOR T1,LIDRP,+P2 ;SAVE AS DROP NUMBER (PORT ON CI)
MOVE T1,P2 ;GET THE CIRCUIT ID WE JUST BUILT
RETSKP ;RETURN SUCCESS.
</pre>
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<pre style="font-family: monospace; font-size: medium; background-color: rgb(238, 238, 238); padding: 1em; text-align: left; border: 2px solid black; white-space: pre; color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px;">;WE KNOW THAT ALL DEVICE NAMES ARE AT MOST 4 BYTES LONG, AND THUS FIT IN A WORD
HRLI T2,(POINT 7,) ;WE STORE THE DATA IN 7 BIT BYTES INTERNALLY
HRRI T2,KONNAM(T1) ;GET POINTER TO DEVICE NAME
NMXC20: ILDB T1,T2 ;GET A BYTE FROM THE DEVICE NAME
JUMPE T1,NMXC21 ;END OF STRING, FALL THROUGH
IDPB T1,P2 ;SAVE IT IN OUR DESTINATION DATA STRING
AOJA T6,NMXC20 ;INCREMENT NUMBER OF BYTES DEPOSITED
NMXC21: MOVEI T1,"-" ;SEPERATOR
IDPB T1,P2 ;STORE IT
AOJ T6, ;COUNT UP CHARACTER
LOAD T1,LIKON,+P1 ;GET THE KONTROLLER NUMBER
PUSHJ P,NMXC28 ;OUTPUT NUMBER IN DECIMAL
MOVEI T1,"-"
IDPB T1,P2 ;STORE THE SEPARATOR
AOJ T6, ;INCREMENT NUMBER OF BYTES
LOAD T1,LIUNI,+P1 ;GET THE UNIT NUMBER
PUSHJ P,NMXC28 ;OUTPUT THE NUMBER IN DECIMAL
JN LILXC,+P1,NMXC22 ;Jump if we are not dealing with a CIRCUIT
LOAD T1,LIDEV,+P1 ;GET THE DEVICE TYPE
CAXE T1,LD.CIP ;IS IT A CI?
JRST NMXC22 ;NO, WE ARE DONE
MOVEI T1,"." ;OUTPUT SEPERATOR
IDPB T1,P2 ;STORE IT
AOJ T6, ;AND INCREMENT COUNT
LOAD T1,LIDRP,+P1 ;GET THE DROP NUMBER (PORT ON THE CI)
PUSHJ P,NMXC28 ;AND OUTPUT IT IN DECIMAL
</pre>
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<br>
<br>
<div class="moz-cite-prefix">On 09-Mar-17 13:00, Paul Koning wrote:<br>
</div>
<blockquote
cite="mid:E38A02EC-40C8-4151-B142-1E8346948E02@comcast.net"
type="cite">
<pre wrap="">
</pre>
<blockquote type="cite">
<pre wrap="">On Mar 9, 2017, at 12:27 PM, Timothe Litt <a class="moz-txt-link-rfc2396E" href="mailto:litt@ieee.org"><litt@ieee.org></a> wrote:
..
With respect to an earlier question about CI emulation: The best approach may be to emulate it as multicast ethernet. Setup a couple of groups for each star coupler. Each coupler supports up to 32 nodes. For VMS, half o them hosts, half storage. CI is a 50Mb/s (might be 70, but I remember 50 from the initial doc) CSMA/CD bus.
</pre>
</blockquote>
<pre wrap="">
70 Mb/s is the number I always saw.
</pre>
<blockquote type="cite">
<pre wrap=""> The cabling is redundant (A & B cables), so assign one MC group to each per star. (Yes, there are DECnet drivers for on multiple OSs. I think it was considered a multipoint medium with addresses related to (CI) node numbers rather than an ethernet (broadcast) - but it's been a while.)
</pre>
</blockquote>
<pre wrap="">
I don't think DECnet ever supported CI. It certainly doesn't show up in the DECnet architecture specs anywhere.
paul
</pre>
</blockquote>
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