1960s computer networking

In the 1960s computer networking was essentially synonymous with mainframe computing, and the distinction between local and wide area networks did not yet exist. Mainframes were typically "networked" to a series of dumb terminals with serial connections running on RS-232 or some other electrical interface. If a terminal in one city needed to connect with a mainframe in another city, a 300-baud long-haul modem would use the existing analog Public Switched Telephone Network (PSTN) to form the connection. The technology was primitive indeed, but it was an exciting time nevertheless. I remember taking a computer science class in high school toward the end of the decade, and having to take my box of punch cards down to the mainframe terminal at the university and wait in line for the output from the line printer. Alas, poor Fortran, I knew thee well!

To continue the story, the quality and reliability of the PSTN increased significantly in 1962 with the introduction of pulse code modulation (PCM), which converted analog voice signals into digital sequences of bits. A consequent development was the first commercial touch-tone phone, which was introduced in 1962. Before long, digital phone technology became the norm, and DS-0 (Digital Signal Zero) was chosen as the basic 64-kilobit-per-second (Kbps) channel upon which the entire hierarchy of the digital telephone system was built. A later development was a device called a channel bank, which took 24 separate DS-0 channels and combined them together using time-division multiplexing (TDM) into a single 1.544-Mbps channel called DS-1 or T1. (In Europe, 30 DS-0 channels were combined to make E1.) When the backbone of the Bell telephone system finally became fully digital years later, the transmission characteristics improved significantly for both voice and data transmission due to higher quality and less noise associated with Integrated Services Digital Network (ISDN) digital lines, though local loops have remained analog in many places. But that is getting a little ahead of the story.

The first communication satellite, Telstar, was launched in 1962. This technology did not immediately affect the networking world because of the high latency of satellite links compared to undersea cable communications, but it eventually surpassed transoceanic underwater telephone cables (which were first deployed in 1965 and could carry 130 simultaneous conversations) in carrying capacity. In fact, early in 1960 scientists at Bell Laboratories transmitted a communication signal coast-to-coast across the United States by bouncing it off the moon! By 1965 popular commercial communication satellites such as Early Bird were being widely deployed and used.

As an interesting aside, in 1961 the Bell system proposed a new telecommunications service called TELPAK, which it claimed would lead to an "electronic highway" for communication, but it never pursued the idea. Could this have been an early portent of the "information superhighway" of the mid-1990s?

The year 1969 witnessed an event whose full significance was not realized until more than two decades later: namely, the development of the ARPANET packet-switching network. ARPANET was a project of the U.S. Department of Defense's Advanced Research Projects Agency (ARPA), which became DARPA in 1972. Similar efforts were underway in France and the United Kingdom, but it was the U.S. project that eventually evolved into the present-day Internet. (France's MINTEL packet-switching system, which was based on the X.25 protocol and which aimed to bring data networking into every home, did take off in 1984 when the French government started giving away MINTEL terminals; by the early 1990s, more than 20 percent of the country's population was using it.) The original ARPANET network connected computers at Stanford University, the University of California at Los Angeles (UCLA), the University of California at Santa Barbara (UCSB), and the University of Utah, with the first node being installed at UCLA's Network Measurement Center. A year later, Harvard University, the Massachusetts Institute of Technology (MIT), and a few other prominent institutions were added to the network, but few of those involved could imagine that this technical experiment would someday profoundly affect modern society and the way we do business.

The year 1969 also saw the publication of the first Request For Comments (RFC) document, which specified the Network Control Protocol (NCP), the first transport protocol of ARPANET. The informal RFC process evolved into the primary means of directing the evolution of the Internet and is still used today.

That same year, Bell Laboratories developed the UNIX operating system, a multitasking, multiuser network operating system (NOS) that became popular in academic computing environments in the 1970s. A typical UNIX system in 1974 was a PDP-11 minicomputer with dumb terminals attached. In a configuration with 768 kilobytes (KB) of magnetic core memory and a couple of 200-megabyte (MB) hard disks, the cost of such a system would have been around $40,000. I remember working in those days on a PDP-11 in the cyclotron lab of my university's physics department, feeding in bits of punched tape and watching lights flash. It was an incredible experience.

Many important standards for computer systems also evolved during the 1960s. In 1962, IBM introduced the first 8-bit character encoding system, called Extended Binary-Coded Decimal Interchange Code (EBCDIC). A year later the competing American Standard Code
for Information Interchange (ASCII) was introduced. ASCII ultimately won out over EBCDIC even though EBCDIC was 8-bit and ASCII was only 7-bit. The American National Standards Institute (ANSI) formally standardized ASCII in 1968. ASCII was first used in serial transmission between mainframe hosts and dumb terminals in mainframe computing environments, but it was eventually extended to all areas of computer and networking technologies.

Other developments in the 1960s included the development in 1964 of IBM's powerful System/360 mainframe computing environment, which was widely implemented in government, university, and corporate computing centers. In 1966, IBM introduced the first disk storage system, which employed 50 metal platters, each of which was 2 feet (0.6 meter) wide and had a storage capacity of 5 MB. IBM created the first floppy disk in 1967. In 1969, Intel Corporation released a RAM chip that stored 1 KB of information, which at the time was an amazing feat of engineering.