[ih] Fwd: As Flag Day approaches at CMU

[Guy Almes]

Jack,
   Thanks very much.
   So this was in place by the mid-70s, right?
	-- Guy

On 9/6/25 3:15 PM, Jack Haverty via Internet-history wrote:
> ITS at MIT circa early 1970s used a naming convention for files --
> <device>:<directory>;<name1> <name2>   So, for example, I logged in to
> MIT-DM as JFH.  My files on disk were things like DSK:JFH;THESIS TJ6
> File names were limited to alphanumerics of 6 characters or less
> (motivated by what you could encode into a 36-bit PDP-10 memory location).
> 
> Once the ARPANET and NCPs appeared, the 'net was a new toy, so people of
> course experimented with how to use it.  I don't remember the details or
> timing (sometime in early 1970s), but at but at some point the Message
> Of The Day announced a new capability - you could use files on some
> other ITS machine just by using a different <device> to specify the DSK
> on some other ITS machine.
> 
> So, for example, from the MIT-AI machine a user could get to my file on
> the DM machine by specifying DM:JFH;THESIS TJ6.
> 
> Similarly, from my account on MIT-DM, I could get to another machine's
> files by using a name such as AI:TK;NEWS ITS to get at Tom Knight's file
> on the AI machine.
> 
> This provided more flexibility than FTP.  You could use a remote file in
> any program that knew how to use files on devices.  To the program, the
> remote disk looked and behaved like a local disk. (More or less -
> problems of "global LANs" were still be be surfaced)
> 
> I don't recall at all how this worked, or who implemented it.  IIRC, it
> took advantage of an interprocess communication capability called the
> "JOB/BOJ device", which enabled one program to open a JOB device, and
> another program to open the corresponding BOJ (JOB reversed) device, and
> send whatever they liked back and forth.  But I don't remember details.
> 
> We also had the ability for one process (aka "job") to map some or all
> of another process' address space into its own address space.  I can't
> recall if anyone got motivated to get that working across the ARPANET
> though.   If so, it would probably have been done using the same
> internal mechanisms that got the remote file systems capability.
> 
> However, for anyone curious, the ancient ITS system is online and has
> even been resurrected so you can look at the code or even run it on your
> modern computer - see https://github.com/PDP-10/its
> 
> Jack Haverty (JFH at MIT-DM in the 70s)
> 
> On 9/6/25 09:28, Guy Almes via Internet-history wrote:
>> Noel,
>>   So this was a real networked file system (and not just lots of FTP)?
>>   Very interesting,
>>     -- Guy
>>
>> On 9/6/25 11:35 AM, Noel Chiappa via Internet-history wrote:
>>>
>>>      > From: Guy Almes
>>>
>>>      > There are probably a number of ARPAnet sites where the ARPAnet
>>>      > served this LAN role in the pre-Ethernet days.
>>>
>>> Notably MIT, where the 4 ITS machines shared their file systems over the
>>> ARPANET.
>>>
>>>     Noel
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>