This week marked the 150th anniversary of the telegraph linking the U.S. from coast to coast. This week also marks another communication anniversary – the first message sent from one computer to another computer on ARPANET, the precursor to the Internet.
In what year was the first computer-to-computer link made on ARPANET, the first modern computer network?
The Advanced Research Projects Agency Network (ARPANET), was the world’s first operational packet switching network and the core network that came to make up the global Internet. The network was funded by the Defense Advanced Research Projects Agency (DARPA) of the United States Department of Defense for use by its projects at universities and research laboratories in the US.
Packet switching, today the dominant basis for data communications worldwide, was a new concept at the time of the conception of the ARPANET. Data communications had been based on the idea of circuit switching, as in the traditional telephone circuit, wherein a telephone call reserves a dedicated circuit for the duration of the communication session and communication is possible only between the two parties interconnected.
With packet switching, a data system could use one communications link to communicate with more than one machine by collecting data into datagrams and transmit these as packets onto the attached network link, whenever the link is not in use. Thus, not only could the link be shared, much as a single post box can be used to post letters to different destinations, but each packet could be routed independently of other packets.
The ARPANET consisted of a network composed of small computers called Interface Message Processors (IMPs), that functioned as gateways (today called routers) interconnecting local resources. At each site, the IMPs performed store-and-forward packet switching functions, and were interconnected with modems that were connected to leased lines. The host computers were connected to the IMPs via custom serial communication interfaces.
The initial ARPANET consisted of four IMPs:
- University of California, Los Angeles (UCLA)
- The Stanford Research Institute’s Augmentation Research Center
- University of California, Santa Barbara (UCSB)
- The University of Utah’s Computer Science Department
The first message on the ARPANET was sent by UCLA student programmer Charley Kline, at 10:30 p.m, on October 29, 1969 from Boelter Hall. Supervised by Prof. Leonard Kleinrock, Kline transmitted from the university’s SDS Sigma 7 Host computer to the Stanford Research Institute’s SDS 940 Host computer. The message text was the word “login”; the “l” and the “o” letters were transmitted, but the system then crashed. Hence, the literal first message over the ARPANET was “lo”. About an hour later, having recovered from the crash, the SDS Sigma 7 computer effected a full “login”.
The first permanent ARPANET link was established on November 21, 1969, between the IMP at UCLA and the IMP at the Stanford Research Institute. By December 5, 1969, the entire four-node network was established.
NET CHECK INs:
A total of 37 stations checked in to the net tonight and 3 of those got the answer correct. Congratulations go out to:
- W6KLE – Don
- WA2RPY – Barry
- W6TCB – Kevin
Thank you to everyone for supporting the net and the Association.