Correct.
The layer and component names in DECnet are different from those in other
protocols, OSI as well as TCP/IP. Phase IV tried to move somewhat towards OSI
terminology and of course Phase V completed that move, but Phase III and before
are different. So we have NSP which OSI calls "transport" and ARPAnet calls
TCP (and before that NCP, I think). And Phase III speaks of the "transport"
layer which OSI calls the network layer and ARPAnet calls IP.
Another somewhat confusing thing is that in some cases DECnet has conventional
names for the client, the server, and the protocol, all separate. So we see
NFS/FAL/DAP, NCP/NML/NICE, TLK/LSN/<something>.
NCP as a standardized element, with its protocol NICE, arrived in Phase III. I
was somewhat surprised to find a predecessor of both the program and the
protocol in Phase II for TOPS-20, since as far as I remember there isn't
anything like it in the Phase II version of DECnet/E, nor have I ever seen a
protocol spec for the Phase II version of NICE. Reverse engineering it from
the sources explains the odd message numbering in (phase III) NICE, though: the
numbering starts at 15 because the numbers below that were used (mostly for
similar functions but with quite different encoding) in the Phase II version of
the protocol.
paul
> On Feb 23, 2026, at 3:16 AM, Hans-Ulrich Hölscher via cctalk
> <[email protected]> wrote:
>
> NCP is the user interface for DECnet configuration, not the network stack.
> It is the "Network Control Program", the program to control DECnet
> networking.
> For example:
> NCP> SHOW KNOWN NODES
> will show the node known to the node you execute this command on.
>
> Ulli
>
> Am Mo., 23. Feb. 2026 um 09:09 Uhr schrieb Lars Brinkhoff via cctalk <
> [email protected]>:
>
>> Paul Koning wrote:
>>> NCP didn't reallly exist until Phase III (though TOPS-20 Phase II does
>>> have an NCP, with syntax different from the later one matching no
>>> specification I have ever seen).
>>
>> What does NCP mean in this context? I thought DECnet NCP meant Network
>> Control Program, same as in an ARPANET, CHAOSnet, or SNA context.
>> I.e. a software component now known as "network stack".
>>
