[TUHS] Unix with TCP/IP for small PDP-11s

[clemc@ccc.com (Clem Cole)]

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The Rand API is documented in a couple of papers that have been discussed
here previously.   I'll have to do a little googling to find them.   The
ChaosNET docs are the best MIT docs.


The API pretty much worked this way...  there was one simple kernel hook.
A small mod was done to the old nami routine (what modern UNIX calls
'lookup'), as a path was being parsed, the rest of the path was left in
place made available to other routines.

Thus you could open:  /dev/tcp/xxx  and the string xxx was available in
call that was implementing tcp and was then able to be passed xxx as a
parameter.  Hence, the traditional open/close/read/write was all that was
needed.

Joy codified a new API that was supposed to be more network centric and map
to different network protocols - the thinking being that
open/close/read/write were insufficient semantics for network operations.

Also, the only other issue at the time was that BSD's select(2) did not
exist, and the UNIX I/O were 100% synchronous.  So some other mechanism
(also discussed here) needed to be created to avoid blocking in the
application.  There were a couple of different schemes with V7's
multiplexor call was created by Chesson for DataKit (which was similar to
was used in the UofI code Arpanet code).   Rand, UNET & Chaos had something
else that gave the save async function, who's name I've forgotten at the
moment, but I believe Noel posted the code for same in the last year from
one of the MIT kernels - we had used it at CMU that we had gotten from Rand.

On Mon, May 22, 2017 at 10:51 AM, Steve Simon <steve at quintile.net> wrote:

> hi Clem,
>
> do you have pointers to any documentation on the rand/MIT network API?
>
> -Steve
>
>
>
>
> On 22 May 2017, at 15:09, Clem Cole <clemc at ccc.com> wrote:
>
>
> On Mon, May 22, 2017 at 5:28 AM, Paul Ruizendaal <pnr at planet.nl> wrote:
>
>> There are two other routes to TCP/IP on a PDP11 without split I/D:
>> - 3COM's TCP/IP package (initially an overlay over V7, soon after also
>> over 2BSD);
>>
> ​It's called UNET​
>
>
>
>
>> I believe the source to this is lost.
>>
> ​So far that is true, there are a couple of leads including a couple of
> unread tapes in my own basement.   The original authors and I have been in
> touch.   Assuming we can find and recover it, there is still an open issue
> of copyright.​
>
>
>
>
>> ​.....​
>>
>>
>> Note that these last two options have very different API's
>>
> ​Indeed...​
>
>
>
>
>> and would not be so easy to work with.
>>
> ​Mumble ... it just means post-Joy sockets code does not 'just work.'
>  UNET uses the Rand interface, which is similar to the interface MIT used
> for Chaos and Chesson used for the ARPAnet code at UofI, so there are
> programs that talk to it.   We had mail, ftp and telnet working just fine.​
>
> ​ Back in the day and IIRC we were playing with a port of the MIT SUPDUP
> code but I do not remember if that ever worked on the small address
> machines.​
>
>
>
>
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