[ih] As Flag Day approaches at CMU

[John Day]

That isn’t surprising. IPC in a single system requires shared memory of some sort (There are lots of ways to do it). With separate partitions, they couldn’t share memory. With an IMP, they could go between what was effectively two systems.

If I remember right, a good example from Postel’s Survey was the UCLA CCN 360/91 had a relatively large NCP and OS/360 didn’t do IPC.

> On Sep 6, 2025, at 07:21, Steve Crocker via Internet-history <internet-history at elists.isoc.org> wrote:
> 
> IIRC, UCSB , Arpanet node #3, had an IBM 360/75 running OS/MVT.  Prior to
> being connected to the Arpanet they had a long-suffering attempt to add
> interprocess communication to operating system so two partitions could
> communicate with each other.  As I understand it, they never got it
> working.  However, when they connected the machine to the IMP, two
> partitions could communicate with each other by treating them as processes
> communicating over the Arpanet.
> 
> Steve
> 
> Sent by a Verified
> 
> sender
> 
> 
> On Sat, Sep 6, 2025 at 4:34 AM Olivier MJ Crépin-Leblond via
> Internet-history <internet-history at elists.isoc.org> wrote:
> 
>> Fascinating.
>> I notice there's not mention of IBM VM/CMS which was the mainstay of
>> EARN/BITNET.
>> 
>> Is it because there were no such computers on the Arpanet?
>> Kindest regards,
>> 
>> Olivier
>> 
>> 
>> On 06/09/2025 04:33, Barbara Denny via Internet-history wrote:
>>>  Oops.  Somehow a .  got inserted in the url.
>>> This one should work.
>>> https://self-issued.info/Smiley/Arpanet_Protocol_Thread.html
>>> barbara
>>>     On Friday, September 5, 2025 at 08:10:41 PM PDT, Greg Skinner via
>> Internet-history<internet-history at elists.isoc.org> wrote:
>>> 
>>>  forwarded for Barbara
>>> 
>>>> ----- Forwarded Message -----
>>>> From: Barbara Denny<b_a_denny at yahoo.com>
>>>> To: Internet-history<internet-history at elists.isoc.org>
>>>> Sent: Friday, September 5, 2025 at 07:49:12 PM PDT
>>>> Subject: As Flag Day approaches at CMU
>>>> 
>>>> Some of you might be interested in this link.
>>>> 
>>>> https://self-issued.info/S.miley/Arpanet_Protocol_Thread.html
>>>> 
>>>> It covers cmu messages as flag day approaches.  They were recovered
>> when Jeff Baird was trying to find Scott Fahlman's smiley :-) bboard post.
>>>> 
>>>> The messages include when the ARPAnet  temporarily shut off  NCP twice
>> before flag day.  Vint, was one of those times you ????? I think I remember
>> you mentioned doing this but I wouldn't be surprised if I am wrong.
>>>> 
>>>> barbara
>> 
>> --
>> Internet-history mailing list
>> Internet-history at elists.isoc.org
>> https://elists.isoc.org/mailman/listinfo/internet-history
>> -
>> Unsubscribe:
>> https://app.smartsheet.com/b/form/9b6ef0621638436ab0a9b23cb0668b0b?The%20list%20to%20be%20unsubscribed%20from=Internet-history
>> 
> -- 
> Internet-history mailing list
> Internet-history at elists.isoc.org
> https://elists.isoc.org/mailman/listinfo/internet-history
> -
> Unsubscribe: https://app.smartsheet.com/b/form/9b6ef0621638436ab0a9b23cb0668b0b?The%20list%20to%20be%20unsubscribed%20from=Internet-history