[ih] BBN C-series computers

[Paul Ruizendaal]

> On 24 Oct 2017, at 20:52, James J Dempsey <jjd at jjd.com> wrote:
> 
> The C/70 (as well as the C/60) definitely did have a TCP/IP stack.  One of
> the first uses of the C/70 was to build and run the NU Network Monitoring
> system.  When I arrived at BBN in the Summer of 1981, we were already on
> track to transition ARPANET to TCP/IP, which as we know eventually happened
> on 1 Jan 1983.
> 
> It was important that NU be able to monitor the ARPANET at that point
> because the TENEX-based U program (which previously monitored and controlled
> ARPANET) could not handle TCP.  My memory is that some people thought NU was
> not up to the task by this point, but it was certainly moot since many
> aspects of the U program would not work after the transition.

Thanks for confirming that. Would you recall if the C/70 used the sockets API
or the earlier arpanet API? (I would suspect the latter).

If the former, it would be the only back port of sockets to V7 that I’m
aware of (unless one thinks of 2.8BSD/2.9BSD as being V7).

> The final nail in the coffin of the C-series machines as competitive UNIX
> computers was the fact that there was no virtual memory. I believe the max
> RAM a C/70 could have was 2-megabytes.  That was substantially more than the
> PDP-11s we had available, but really not competive with the DEC VAX series.

Yes: the C/60 ad also says maximum 2 MB of real memory.

With 20 bit addresses and byte addressing, logical address space is 1 MB. That
suggests that the C/70 must have had some sort of address translation (and
probably some sort of memory protection as well).