NLS, or the "oN-Line System", was a revolutionary computer collaboration system from the 1960s. Designed by Douglas Engelbart and implemented by researchers at the Augmentation Research Center (ARC) at the Stanford Research Institute (SRI), the NLS system was the first to employ the practical use of hypertext links, the mouse, raster-scan video monitors, information organized by relevance, screen windowing, presentation programs, and other modern computing concepts. It was funded by the Defense Advanced Research Projects Agency, NASA, and the U.S. Air Force.
Douglas Engelbart developed his concepts while supported by the US Air Force from 1959 to 1960, and published a framework in 1962. The strange acronym, NLS (instead of OLS) was an artifact of the evolution of the system. His first computers were not able to support more than one user at a time. First was the CDC 160A in 1963 which had very little programming power of its own.
As a stopgap measure, the team developed a system where off-line users — that is, anyone not sitting at the one terminal available — could still edit their documents by punching a string of commands onto paper tape with a Flexowriter. Once the tape was complete, then an off-line user would feed into the computer the paper tape on which the last document draft had been stored, followed by the new commands to be applied, and then the computer would print out a new paper tape containing the latest version of the document. Without interactive visualization, this could be awkward, since the user had to mentally simulate the cumulative effects of their commands on the document text. On the other hand, it matched the workflow of the 1960s office, since managers would give marked-up printouts of documents to secretaries.
The design continued to support this "off-line" workflow, as well as an interactive "on-line" ability to edit the same documents. To avoid two acronyms starting with the same letter, the Off-Line Text System was abbreviated FLTS, while the On-Line Text System was abbreviated NLTS. As the system evolved to support more than just text, the "T" was dropped and the interactive version became known as NLS.
Robert Taylor, who had a background in psychology, provided support from NASA. When Taylor moved to the Information Processing Techniques Office of the US Defense Department's Advanced Research Projects Agency, he was able to provide even more funding to the project. In 1965, NLS development moved to a CDC 3100. Jeff Rulifson joined SRI in 1966 and became the lead programmer for NLS until he left in 1973.
NLS development moved to a Scientific Data Systems SDS 940 computer running the Berkeley Timesharing System in 1968. It had an approximately 96 MB storage disk. It could support up to 16 workstations, which were composed of a raster-scan monitor, a three-button mouse, and a device known as a chord keyset. The input of typed text was sent from the keyboard to a specific subsystem that relayed the information along a bus to one of two Display Controllers and Display Generators. The inputted text then was sent to a 5-inch (127 mm) cathode ray tube (CRT), which was enclosed by a special cover and a superimposed video image was then received by a professional-quality black-and-white TV camera. The TV camera information was then sent to the closed-circuit Camera Control and Patch Panel, and, finally, displayed on each workstation's video monitor.
NLS was demonstrated by Engelbart on December 9, 1968, to a large audience at that year's Fall Joint Computer Conference in San Francisco. This has since been dubbed "The Mother of All Demos", as it not only demonstrated the groundbreaking features of NLS, but also involved assembling some remarkable state-of-the-art video technologies. Engelbart's onstage terminal keyboard and mouse was linked by a homemade modem at 2400 baud via a leased line that connected to ARC's SDS 940 computer in Menlo Park, 48 kilometer southeast of San Francisco, and two microwave links carried video from Menlo Park back to a massive Eidophor video projector loaned by the NASA Ames Research Center. On a 22-foot (6.7 meter) high screen with video insets, the audience could follow Engelbart's actions on his display, observe how he used the mouse, and watch as members of his team in Menlo Park joined in the presentation.
One of NLS's most revolutionary features, the Journal, was developed in 1970 by Australian computer engineer David A. Evans as part of his doctoral thesis. The Journal was a primitive hypertext-based groupware program which can be seen as a predecessor (if not the direct ancestor) of all contemporary server software that supports collaborative document creation (like wikis). It was used by ARC members to discuss, debate, and refine concepts in the same way that wikis are being used today. The journal was used to store documents for the Network Information Center and early network email archives. Most Journal documents have been preserved in paper form, and are stored in Stanford University's archives; they are a valuable record of the evolution of the ARC community from 1970 until commercialization began in 1976. An additional set of Journal documents exist at the Computer History Museum, along with a large collection of ARC backup tapes starting from the early 1970s, as well as some of the tapes from the 1960s from the SDS 940.
In 1970 NLS was ported to the PDP-10 computer (as modified by BBN to run the TENEX operating system). By mid-1971 the TENEX implementation of NLS was put into service as the new Network Information Center, but even this computer could only handle a small number of simultaneous users. Access was possible via either custom-built display workstations, or simple typewrite-like terminals, less expensive and more common at the time. By 1974 the NIC had spun off to a separate project on its own computer.
All of the features of NLS were in support of Engelbart's goal of augmenting collective knowledge work and therefore focused on making the user more powerful, not simply on making the system easier to use. These features therefore supported a full-interaction paradigm with rich interaction possibilities for a trained user, rather than what Engelbart referred to as the WYSIAYG (What You See Is All You Get) paradigm that came later.
Engelbart said, "Many of those firsts came right out of the staff's innovations — even had to be explained to me before I could understand them. [The staff deserves] more recognition."
The downfall of NLS, and subsequently, of ARC in general, was the program's difficult learning curve. NLS was not designed to be easy to learn; it employed the heavy use of program modes, relied on a strict hierarchical structure, did not have a point-and-click interface, and forced the user to have to learn cryptic mnemonic codes to do anything useful with the system. The chord keyset, which complemented the modal nature of NLS, forced the user to learn a 5-bit binary code if they did not want to use the keyboard. Finally, with the arrival of the ARPA Network at SRI in 1969, the time-sharing technology that seemed practical with a small number of users became impractical over a distributed network; time-sharing was rapidly being replaced by individual minicomputers (and later microcomputers) and workstations. Attempts to port NLS to other hardware, such as the PDP-10 and later on the DECSYSTEM-20, were successful, but did nothing to spread NLS beyond SRI.
Frustrated by the direction of Engelbart's "bootstrapping" crusade, many top SRI researchers left, with many ending up at the Xerox Palo Alto Research Center, taking the mouse idea with them. SRI sold NLS to Tymshare in 1977 and renamed it Augment, and Tymshare was, in turn, sold to McDonnell Douglas in 1984.
Some of the "full-interaction" paradigm lives on in different systems, including the Hyperwords Add-On for Mozilla Firefox. The Hyperwords concept grew out the Engelbart web-documentary Invisible Revolution. The aim of the project is to allow users to interact with all the words on the Web, not only the links. Hyperwords works through a simple hierarchical menu but also gives users access to keyboard "phrases" in the spirit of NLS commands and features Views which are inspired by the powerful NLS ViewSpecs. The Views allow the user to re-format web pages on the fly. Engelbart has been on the Advisory Board of The Hyperwords Company since its inception 2006.