NLS (computer system)

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NLS, or the "oN-Line System", was a revolutionary computer collaboration system designed by Douglas Engelbart and the researchers at the Augmentation Research Center (ARC) at the Stanford Research Institute (SRI) during the 1960s. The NLS system was the first to employ the practical use of hypertext links, the mouse (co-invented by Engelbart and colleague Bill English), raster-scan video monitors, information organized by relevance, screen windowing, presentation programs, and other modern computing concepts.



Funded by DARPA, NASA, and the U.S. Air Force, NLS was designed around a Scientific Data Systems SDS 940 time-sharing computer with 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. The lead programmer was Jeff Rulifson.

The strange acronym, NLS (instead of OLS) arose from the fact that Engelbart had been unable to get all the funding he needed at once; he had been forced to develop his system incrementally while he applied to the federal government for more money. His first two computers (before the SDS 940) were not able to support more than one user at a time.

As a crude stopgap measure, he 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. Obviously, without interactive visualization, this was very awkward and the user had to monitor the cumulative effects of his commands on his document in his own head.

Once the tape was complete, then the 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. This cumbersome system was first called the Z-Code System, because the commands all began with the letter Z, and later, the Off-Line System (OLS). When the funding finally materialized for an advanced SDS 940 where multiple users could be on-line simultaneously, the acronym OLS was already taken, so Engelbart settled for NLS.

Its development largely complete, NLS was demonstrated by Engelbart on the 9th December 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 was linked to a massive video projector loaned by NASA Ames and, via leased telephone lines, to ARC's SDS 940 computer in Menlo Park. On a 22-foot 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.[1]

One of NLS's most revolutionary features, the Journal, was developed in 1970 by Australian computer engineer David A. Evans[2] 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. 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 to its collapse in 1976.

The NLS was implemented using several domain-specific languages implemented with the Tree Meta compiler-compiler [3].


All of the features of NLS were in support of Douglas Engelbart's goal of augmenting collective knowledge work [4] and therefore focused on making the user more powerful, not simply on making the system easier to use [5]. The features listed below therefore were in support of a full-interaction paradigm with rich interaction possibilities for a trained user, rather than what Doug Engelbart refers to as the WYSIAYG (What You See Is All You Get)[6] paradigm that came later. The following list is from Doug Engelbart's Bootstrap Institute Website[7].

  • the mouse
  • 2-dimensional display editing
  • in-file object addressing, linking
  • hypermedia
  • outline processing
  • flexible view control
  • multiple windows
  • cross-file editing
  • integrated hypermedia email
  • hypermedia publishing
  • document version control
  • shared-screen teleconferencing
  • computer-aided meetings
  • formatting directives
  • context-sensitive help
  • distributed client-server architecture
  • uniform command syntax
  • universal "user interface" front-end module
  • multi-tool integration
  • grammar-driven command language interpreter
  • protocols for virtual terminals
  • remote procedure call protocols
  • compilable "Command Meta Language"

"Many of those firsts came right out of the staff's innovations -- even had to be explained to me before I could understand them. They deserve more recognition." Douglas Engelbart.[8]

Decline and succession

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 famed Xerox PARC, 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 the early 1980s. The HyPerform program sold by NDMA Inc. is a descendant of NLS and Augment.

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 Doug Engelbart web-documentary Invisible Revolution[9]. 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 hierarchal 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. Douglas Engelbart has been on the Advisory Board of The Hyperwords Company since its inception 2006.

See also


  1. Wired
  2. It is important to not confuse Dr. Evans with the numerous other persons who share the same name. He is currently Managing Director and CEO of MRI magnet startup Magnetica and participated in the 1998 symposium honoring Engelbart's work.
  3. Engelbart, D., Study for the development of Human Augmentation Techniques. Final Report, July 1968. Sections 4 and 5.
  4. Invisible Revolution
  5. Invisible Revolution
  6. Harvey Lehtmann
  9. Invisible Revolution

External links

ja:NLS pl:ON-Line System pt:NLS

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