[ih] NCP and TCP implementations

Dan Lynch dan at lynch.com
Fri Jul 24 10:30:35 PDT 2020

The original TCP for Tenex was written in BCPL in user space (rather than in the underlying system space) and once it was reasonably stable it was converted to Macro-10 so it could be folded into the system. I believe Bill Plummer (RIP) did all that work. I helped him in the debugging tasks while I was at SRI. 


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> On Jul 21, 2020, at 6:43 PM, Noel Chiappa via Internet-history <internet-history at elists.isoc.org> wrote:
>> On 20.03.10, vinton cerf via Internet-history wrote:
>> Steve Kirsch asks in what languages NCP and TCP were written.
>> ...
>> Another version was written for PDP-11/23 by Jim Mathis but not clear in
>> what language.
> I think I answered this when it was first posted, but I now have some
> additional data (I think).
> It was written in MACRO-11; PDP-11 assembler with a powerful macro capability.
> After some poking around in a copy of the file system of the v6 Unix
> timesharing system of the CSR group at MIT, which has all sort of goodies in
> it (including a copy of the NCP for v6 Unix), I have recovered a copy of that
> TCP, if anyone wants it.
> I'm not sure if it was done for the -11/23; we got MOS (Jim's OS, and other
> software, including the TCP and an early version of the Port Expander codea)
> early on, and I seem to recall that the -11/23 didn't come out until after we
> had MOS. I'd have to look up exactly when the KDF11 was released to be sure, if
> it's important. MOS had conditionals to work on the -11/03 and also the -11/20
> and -11/40 (binary for the -11/40 will run on the /23). I think the TCP, etc
> were written for the -11/03.
>> Dave Clark did one for IBM PC (assembly language/??)
> No, but Dave did I think at least two others; possibly one in BCPL? for the
> Tripos operating system from Cambridge, and definitely one in BCPL for the
> Alto (MIT got several as a donation from Xerox). Before the latter, he also
> worked on the Multics one (in PL/I) although someone else whose name my
> failing brain can't remember at the moment worked on that before him. The Alto
> one was later translated into C by Larry Allen for the CSR v6 Unix, which I
> used as the base on one I did for Bridge.
> The one for the PC was done by John Romkey and David Bridgham, in C; the CSR
> machine dump has that one too, if anyone wants it.
>    Noel
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