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‘LO’ and behold: a historic internet milestone

May 10, 2019
by Mark Ollig

Under what was called “a national sense of urgency,” President Dwight D. Eisenhower authorized Department of Defense Directive 5105.15.

Signed Feb. 7, 1958, this directive founded the Advanced Research Projects Agency (ARPA).

Four months earlier, the Soviet Union had launched a missile containing Sputnik 1, the world’s first artificial satellite to orbit the Earth.

This action caused much anxiety and fear among US citizens who worried the next Soviet missile might have a nuclear warhead attached instead of a harmless, beeping satellite.

ARPA was also known as the Defense Advanced Research Projects Agency (DARPA).

It supported sharing computing resources from geographically-separated computers across the country by transmitting and receiving wide-area data-packet switching protocol transmissions through its network.

The ARPA network was also called ARPANET. It seems folks back then liked a lot of acronyms.

ARPANET laid the groundwork for today’s internet.

Oct. 29, 1969, the first host-to-host message between different model computers was tested over ARPANET.

The first computer node on the ARPANET was a Scientific Data Systems (SDS) Sigma-7 32-bit host computer node located at the University of California, Los Angeles (UCLA).

This computer node was physically linked on dedicated telephone line facilities over the ARPANET to a second node, an SDS-940 time-sharing host computer located 350 miles south at the Stanford Research Institute (SRI) in Menlo Park, CA.

Using serial communication protocols, the Sigma-7 computer was physically cabled to a router to forward/receive data packets over the ARPANET to the SDS-940 computer’s router.

These routers or Interface Message Processors (IMP) were each the size of a refrigerator.

Remember, this is 1969.

An IMP would be identified today as an internet router used for connecting computing networks and passing packets of data.

The telephone lines served as the physical transport facilities to the second node in this network; the SRI host computer, which connected to its own IMP.

The ARPANET data transport facilities functioned as the internet between the two IMPs.

Charley Kline, a programmer and student at UCLA, was attempting to send the login command, “LOG” to the SRI SDS-940 computer from his user teletype terminal connected to the Sigma-7 computer.

“I would type a character. It would go into my computer. My software would take it; wrap around it all the necessary software to send it to the IMP. The IMP would take it and say, ‘Oh, this is supposed to go up to SRI,’” Kline said during a 2009 National Public Radio interview.

Kline typed the letters “L” and “O.” The Sigma-7 computer sent them to the SRI SDS-940 computer over the ARPANET link connecting the two machines.

He was talking on the telephone with Bill Duvall, another programmer, operating the SDS-940 computer at the SRI, in Menlo Park, CA.

Duvall confirmed to Kline the SDS-940 computer received and recognized his typed characters “L” and “O.”

However, a problem occurred when Kline typed in the final letter “G.”

The SDS-940 computer did not receive the “G.”

A memory buffer at SRI had become full; causing the SDS-940 computer to crash.

And so, the first word successfully transmitted over the original internet was LO.

Meanwhile, Duvall had realized what caused the crash. He needed to increase the size of a memory buffer on the SRI SDS-940 computer; this took about an hour to complete.

Once again, Kline typed the “L-O-G” command from his terminal at UCLA.

This time, the three-letter word was successfully recognized by the SDS-940 computer at the Stanford Research Institute.

Kline was remotely logged in.

The SDS-940 computer had automatically filled-in the “I-N” to complete the “L-O-G-I-N” command.

He was now able to type computing commands from his remote terminal to the SDS-940.

Kline’s teletype terminal in Los Angeles was operating as if it was connected to the SDS-940 computer located in Menlo Park.

The importance of Kline and Duvall’s work meant a dedicated user terminal connected to each computer on the network was no longer needed. One user terminal would be able to access any of the computers connected to the ARPANET.

The notes written by Kline show the first message sent over the ARPANET occurred Oct. 29, 1969, at 10:30 p.m. from 3420 Boelter Hall at UCLA.

Kline’s handwritten notes of this historic internet milestone can be seen at https://bit.ly/2Vh1pYo.

A photo of an Interface Message Processor can be seen at https://bit.ly/2WnDovk.

The ARPANET diagram with the UCLA and SRI computer nodes can be viewed here: https://bit.ly/2V45E4w.

I’ve been asked if it’s possible for today’s internet to crash and altogether stop working.

The design of the internet; using packet switching, distributed routing tables, and mirrored/duplicated data servers and resources, makes it exceptionally resilient.

There are redundancies in the hardware and software. The internet’s connection paths can alternate. It uses varied network routing, which ensures the internet’s stability.

It’s highly-unlikely the internet would see a total breakdown.

Of course, physical sections of the internet can be severed, thus disconnecting its availability for end-users.

Fiber-optic cables can be cut, and Internet Service Providers hosting websites and social media networks can suffer outages as a result of internal faults, or through cyber-attacks by malicious hackers.

The Department of Defense Directive 5105.15 can be read at https://bit.ly/2VSaBBY.


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