Lawrence Gordon Tesler (April 24, 1945 – February 16, 2020) was an American
computer scientist
A computer scientist is a person who is trained in the academic study of computer science.
Computer scientists typically work on the theoretical side of computation, as opposed to the hardware side on which computer engineers mainly focus ( ...
who worked in the field of
human–computer interaction
Human–computer interaction (HCI) is research in the design and the use of computer technology, which focuses on the interfaces between people ( users) and computers. HCI researchers observe the ways humans interact with computers and design ...
. Tesler worked at
Xerox PARC,
Apple
An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ances ...
,
Amazon
Amazon most often refers to:
* Amazons, a tribe of female warriors in Greek mythology
* Amazon rainforest, a rainforest covering most of the Amazon basin
* Amazon River, in South America
* Amazon (company), an American multinational technolog ...
, and
Yahoo!
Yahoo! (, styled yahoo''!'' in its logo) is an American web services provider. It is headquartered in Sunnyvale, California and operated by the namesake company Yahoo! Inc. (2017–present), Yahoo Inc., which is 90% owned by investment funds ma ...
While at PARC, Tesler's work included
Smalltalk
Smalltalk is an object-oriented, dynamically typed reflective programming language. It was designed and created in part for educational use, specifically for constructionist learning, at the Learning Research Group (LRG) of Xerox PARC by ...
, the first dynamic
object-oriented programming
Object-oriented programming (OOP) is a programming paradigm based on the concept of " objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of ...
language, and
Gypsy
The Romani (also spelled Romany or Rromani , ), colloquially known as the Roma, are an Indo-Aryan ethnic group, traditionally nomadic itinerants. They live in Europe and Anatolia, and have diaspora populations located worldwide, with si ...
, the first
word processor
A word processor (WP) is a device or computer program that provides for input, editing, formatting, and output of text, often with some additional features.
Word processor (electronic device), Early word processors were stand-alone devices ded ...
with a
graphical user interface
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows User (computing), users to Human–computer interaction, interact with electronic devices through graphical icon (comp ...
(GUI) for the
Xerox Alto
The Xerox Alto is a computer designed from its inception to support an operating system based on a graphical user interface (GUI), later using the desktop metaphor. The first machines were introduced on 1 March 1973, a decade before mass-market G ...
. During this, along with colleague Tim Mott, Tesler developed the idea of
copy and paste functionality and the idea of
modeless software. While at Apple, Tesler worked on the
Apple Lisa
Lisa is a desktop computer developed by Apple, released on January 19, 1983. It is one of the first personal computers to present a graphical user interface (GUI) in a machine aimed at individual business users. Its development began in 1978. ...
and the
Apple Newton, and helped to develop
Object Pascal
Object Pascal is an extension to the programming language Pascal that provides object-oriented programming (OOP) features such as classes and methods.
The language was originally developed by Apple Computer as ''Clascal'' for the Lisa Work ...
and its use in application programming toolkits including
MacApp.
Biography
Early career
Tesler was born on April 24, 1945, in the
Bronx
The Bronx () is a borough of New York City, coextensive with Bronx County, in the state of New York. It is south of Westchester County; north and east of the New York City borough of Manhattan, across the Harlem River; and north of the New ...
in
New York City
New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the U ...
, to Jewish parents Isidore, an anesthesiologist, and Muriel ().
Tesler lived in the Bronx through his childhood and graduated from the
Bronx High School of Science
The Bronx High School of Science, commonly called Bronx Science, is a public specialized high school in The Bronx in New York City. It is operated by the New York City Department of Education. Admission to Bronx Science involves passing the Sp ...
in 1961. While in high school, he was guided towards computers by a teacher after showing the teacher an algorithm for generating
prime number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only way ...
s. Through this, he learned of a program at
Columbia University
Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manha ...
where he was able to spend a half-hour each week on their computer systems, through which he taught himself programming before college.
He went on to
Stanford University in 1961 when he was 16, studying
computer science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (includin ...
and graduating in 1965 with a degree in mathematics.
At Stanford, he had spent time as a student programmer for
Joshua Lederberg
Joshua () or Yehoshua ( ''Yəhōšuaʿ'', Tiberian: ''Yŏhōšuaʿ,'' lit. 'Yahweh is salvation') ''Yēšūaʿ''; syr, ܝܫܘܥ ܒܪ ܢܘܢ ''Yəšūʿ bar Nōn''; el, Ἰησοῦς, ar , يُوشَعُ ٱبْنُ نُونٍ '' Yūšaʿ ...
on the
LINC platform,
and was a colleague of
Larry Breed,
Charles Brenner,
Douglas Hofstadter
Douglas Richard Hofstadter (born February 15, 1945) is an American scholar of cognitive science, physics, and comparative literature whose research includes concepts such as the sense of self in relation to the external world, consciousness, an ...
,
Roger Moore
Sir Roger George Moore (14 October 192723 May 2017) was an English actor. He was the third actor to portray fictional British secret agent James Bond in the Eon Productions film series, playing the character in seven feature films between 1 ...
, and Bill Strachan.
During college and afterward, Tesler did some programming jobs on the side, and after graduation, worked as a consultant offering his programming services in the area. As he was one of only a few computer programmers listed in the Palo Alto phone directory he received a good deal of work. However, a regional recession caused this consulting work to dry up.
Tesler also worked at
Stanford Artificial Intelligence Laboratory
Stanford University has many centers and institutes dedicated to the study of various specific topics. These centers and institutes may be within a department, within a school but across departments, an independent laboratory, institute or center ...
(SAIL) in the late 1960s. With
Horace Enea
Quintus Horatius Flaccus (; 8 December 65 – 27 November 8 BC), known in the English-speaking world as Horace (), was the leading Roman lyric poet during the time of Augustus (also known as Octavian). The rhetorician Quintilian regarded his '' ...
he designed Compel, an early single assignment language. This
functional programming
In computer science, functional programming is a programming paradigm where programs are constructed by applying and composing functions. It is a declarative programming paradigm in which function definitions are trees of expressions that ...
language was intended to make concurrent processing more natural and was used to introduce programming concepts to beginners.
During his time at Stanford, Tesler had participated in the
counterculture of the 1960s
The counterculture of the 1960s was an anti-establishment cultural phenomenon that developed throughout much of the Western world in the 1960s and has been ongoing to the present day. The aggregate movement gained momentum as the civil rights mo ...
, including the
anti-Vietnam War protests. In the late 1960s, Tesler became involved in the
Midpeninsula Free University, part of the
Free Speech Movement
The Free Speech Movement (FSM) was a massive, long-lasting student protest which took place during the 1964–65 academic year on the campus of the University of California, Berkeley. The Movement was informally under the central leadership of B ...
, where he taught classes with titles such as "How to end the IBM Monopoly", "Computers Now", and "Procrastination".
Xerox PARC
Tesler left Stanford Artificial Intelligence Laboratory due to a number of factors in the early 1970s; he recognized that artificial intelligence would not be a usable technology for many years, and his marriage to his college girlfriend had recently ended in divorce. He took his daughter and moved to Oregon with a number of
Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
veterans who were returning there to build homes. There was little computing technology in this area and he could not get a job with the local bank, the only firm nearby with a computer system.
He called Stanford to see if they had anything, and learned that
Alan Kay
Alan Curtis Kay (born May 17, 1940) published by the Association for Computing Machinery 2012 is an American computer scientist best known for his pioneering work on object-oriented programming and windowing graphical user interface (GUI) d ...
, whom Tesler had worked with while at SAIL and then a member of
Xerox Palo Alto Research Center (PARC), had been actively looking for him shortly after his departure. Kay wanted Tesler to join him at PARC.
Tesler could not be hired at PARC due to a hiring freeze, so Tesler instead took a short-term project offered by
Les Earnest
Lester Donald Earnest (born December 17, 1930) is an American computer scientist.
Education and career
After receiving his B.S. in electrical engineering from the California Institute of Technology (Caltech) in 1953, he began his career as a co ...
from SAIL to write a "document compiler", a means to easily produce printable manuals from simple text files. In order to carry out this project, Tesler wrote Pub, which was then recognized as one of the first uses of
markup language
Markup language refers to a text-encoding system consisting of a set of symbols inserted in a text document to control its structure, formatting, or the relationship between its parts. Markup is often used to control the display of the document ...
; it was later distributed on ARPANet.

PARC approached Tesler with an offer in 1971, but wanted to place Tesler in the On-Line Office System Group. Tesler had been more interested in Xerox's work with personal computers, so he turned down the offer. By early 1973, PARC had established development of the
Xerox Alto
The Xerox Alto is a computer designed from its inception to support an operating system based on a graphical user interface (GUI), later using the desktop metaphor. The first machines were introduced on 1 March 1973, a decade before mass-market G ...
, the first computer system designed around a
graphical user interface
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows User (computing), users to Human–computer interaction, interact with electronic devices through graphical icon (comp ...
(GUI), and Tesler accepted an offer for a position splitting his time between the Office System Group and the Learning Research Group, which Kay was heading.
Some of Tesler's main projects at PARC were the
Gypsy
The Romani (also spelled Romany or Rromani , ), colloquially known as the Roma, are an Indo-Aryan ethnic group, traditionally nomadic itinerants. They live in Europe and Anatolia, and have diaspora populations located worldwide, with si ...
word processor
A word processor (WP) is a device or computer program that provides for input, editing, formatting, and output of text, often with some additional features.
Word processor (electronic device), Early word processors were stand-alone devices ded ...
for the Office System Group, and
Smalltalk
Smalltalk is an object-oriented, dynamically typed reflective programming language. It was designed and created in part for educational use, specifically for constructionist learning, at the Learning Research Group (LRG) of Xerox PARC by ...
, the first dynamic
object-oriented programming
Object-oriented programming (OOP) is a programming paradigm based on the concept of " objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of ...
language, with the Learning Research Group.
While working on Gypsy, Tesler and his colleague
Tim Mott started writing ideas down envisioning the future of interactive computer use, considering current text-based user interfaces would move to GUIs with icons representing documents, and to develop ease-of-use. From there, the two developed the basic
copy and paste function, now a standard feature in computing.
Tesler also established the idea that computer interfaces should be
modeless, where all actions are available to a user at all times, rather than modal, requiring the user to enter a specific mode to perform them. Gypsy was programmed to include both of these concepts.
Tesler also was part of a team with
Adele Goldberg and Douglas Fairbairn that worked on the
Xerox NoteTaker
The Xerox NoteTaker is a portable computer developed at Xerox PARC in Palo Alto, California, in 1978. Although it did not enter production, and only around ten prototypes were built, it strongly influenced the design of the later Osborne 1 and Com ...
, a portable computer system Alan Kay had envisioned. Tesler, then a novice to hardware programming and design, worked with Fairbairn on the design, which included the first functioning
Ethernet
Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in ...
protocol written in software rather than on hardware.
Tesler and Fairbairn took the NoteTaker prototype on cross-country trips to demonstrate the unit to Xerox executives. At one layover during the trip, Tesler and Fairbairn briefly tested the unit at an airport and while in flight, which Tesler believed was the first-ever use of a computer in these situations.
The NoteTaker did not gain traction as Xerox had turned its attention back to the Xerox Alto.
Tesler was a proponent of ease-of-use for user interfaces while at PARC. Tesler is considered the originator of the phrase "user-friendly" as a measure of
usability
Usability can be described as the capacity of a system to provide a condition for its users to perform the tasks safely, effectively, and efficiently while enjoying the experience. In software engineering, usability is the degree to which a sof ...
after a salesman told him that word processors were difficult to sell because they were "just so unfriendly".
Tesler is also tied to the origins of the phrase "
what you see is what you get"; he and his colleagues were complaining about the way documents printed out differently to their appearance on the screen. Tesler said, "What you see on the screen should be what you get when you print it." Another person simplified this to the well-known abbreviation "WYSIWYG" which gained traction as a functional goal within PARC and beyond.
Tesler also is credited with coining the term "
browser" after creating a Smalltalk code browser in response to a coworker having difficulty in parsing through someone else's code.
Tesler had been present during both of
Steve Jobs
Steven Paul Jobs (February 24, 1955 – October 5, 2011) was an American entrepreneur, industrial designer, media proprietor, and investor. He was the co-founder, chairman, and CEO of Apple; the chairman and majority shareholder of Pixar; ...
's fateful visits to PARC in late 1979, a couple of years after Jobs had cofounded
Apple Computer
Apple Inc. is an American multinational technology company headquartered in Cupertino, California, United States. Apple is the largest technology company by revenue (totaling in 2021) and, as of June 2022, is the world's biggest company ...
. During the first visit, Tesler demonstrated to Jobs the Xerox Alto, including its
computer mouse
A computer mouse (plural mice, sometimes mouses) is a hand-held pointing device that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, which allows a smooth ...
-driven GUI features, Gypsy, and Smalltalk. While the Alto had been a mere curiosity for Xerox, Jobs saw a huge amount of potential in the graphical interface, and immediately after returning to Apple's headquarters, set his team on creating a similar graphical user interface for their first product, the
Apple Lisa
Lisa is a desktop computer developed by Apple, released on January 19, 1983. It is one of the first personal computers to present a graphical user interface (GUI) in a machine aimed at individual business users. Its development began in 1978. ...
, incorporating additional information provided by Xerox, later refined into the first
Apple Macintosh
The Mac (known as Macintosh until 1999) is a family of personal computers designed and marketed by Apple Inc. Macs are known for their ease of use and minimalist designs, and are popular among students, creative professionals, and software ...
. However, while the Macintosh was Apple's flagship to becoming a major manufacturer of personal computers, Xerox fell behind.
Apple Computer

Tesler was one of several Xerox PARC employees who left the company in 1980 to join Apple Computer following Jobs's visits.
Tesler said his reasons for leaving included the fact that Apple had clearly gotten the idea of computers and was much more excited in the work PARC was doing while Xerox still thought itself a copier company, and that he found Apple's management much more approachable than Xerox's.
Tesler started at Apple in July 1980 supporting the development of the Apple Lisa, and worked for them until 1997, holding various positions, including Vice President of AppleNet, the division within Apple working on Internet technologies (not to be confused with
AppleNet
AppleTalk is a discontinued proprietary protocol, proprietary protocol stack, suite of networking protocols developed by Apple Computer for their Macintosh, Macintosh computers. AppleTalk includes a number of features that allow local area netwo ...
, the never-shipped network for the Lisa), Vice President of the
Advanced Technology Group, and Chief Scientist.
[Larry Tesler personal home page, CV](_blank)
/ref>
Part of Tesler's work with the Lisa was to develop object-oriented programming
Object-oriented programming (OOP) is a programming paradigm based on the concept of " objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of ...
extensions to the Pascal programming language allowing easier manipulation of the GUI. Tesler worked with Pascal's creator, Niklaus Wirth
Niklaus Emil Wirth (born 15 February 1934) is a Swiss computer scientist. He has designed several programming languages, including Pascal, and pioneered several classic topics in software engineering. In 1984, he won the Turing Award, generally ...
, to develop Object Pascal
Object Pascal is an extension to the programming language Pascal that provides object-oriented programming (OOP) features such as classes and methods.
The language was originally developed by Apple Computer as ''Clascal'' for the Lisa Work ...
in 1985 which was used to create the Lisa Toolkit. When Apple moved onto the Macintosh platform, the same concepts were brought forward to create MacApp, a similar Object Pascal-based class library for the Macintosh's GUI functions released in 1985.
Starting in 1990, Tesler was named vice president of Apple's Newton Group under the Advanced Technology Group, and led the efforts of developing the Apple Newton, one of the first personal digital assistant
A personal digital assistant (PDA), also known as a handheld PC, is a variety mobile device which functions as a personal information manager. PDAs have been mostly displaced by the widespread adoption of highly capable smartphones, in part ...
s and predecessor of the tablet computer
A tablet computer, commonly shortened to tablet, is a mobile device, typically with a mobile operating system and touchscreen display processing circuitry, and a rechargeable battery in a single, thin and flat package. Tablets, being comput ...
. However, Tesler claimed some decisions related to the Newton's release, such as deciding against an Apple-developed handwriting recognition
Handwriting recognition (HWR), also known as handwritten text recognition (HTR), is the ability of a computer to receive and interpret intelligible handwritten input from sources such as paper documents, photographs, touch-screens and other dev ...
software, over a third-party which slowed down the device, were estimated to have cost Apple millions of dollars. Tesler voluntarily left the group just before the Newton shipped in 1993 and became Apple's chief scientist within the Advanced Technology Group. He explored a number of potential projects being developed by the group, but these had been too risky for Apple at the time, so the group focused on networking strategies. Tesler decided to leave Apple in 1997. One of his last acts was to close the Advanced Technology Group as Apple was struggling too much financially to support such a research program at that time.
In 1991, Tesler contributed the article "Networked Computing in the 1990s" to the ''Scientific American
''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many famous scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it. In print since 1845, it i ...
'' Special Issue on Communications, Computers, and Networks of September 1991.
Later career
One of the last programs that Tesler oversaw at Apple was a programming language aimed for use by schoolchildren, named Cocoa (unrelated to the Cocoa application programming interface later released by Apple). With Apple's permission, Tesler spun out and cofounded Stagecast Software in Palo Alto in 1997, where his small team further developed Stagecast Creator, a programming environment aimed for educational uses that had been under development at Apple. Stagecast Creator was released in 1999, just at the time that the education market had turned financially downhill, and sales of the program were not sufficient to keep the company in business. Tesler dismissed most of the employees in mid-2000, and then left, leaving two employees to continue the company.
Tesler joined Amazon
Amazon most often refers to:
* Amazons, a tribe of female warriors in Greek mythology
* Amazon rainforest, a rainforest covering most of the Amazon basin
* Amazon River, in South America
* Amazon (company), an American multinational technolog ...
in Seattle
Seattle ( ) is a port, seaport city on the West Coast of the United States. It is the county seat, seat of King County, Washington, King County, Washington (state), Washington. With a 2020 population of 737,015, it is the largest city in bo ...
in October 2001. Initially he had been hired as a vice president of engineering, and was shortly thereafter promoted to the vice president of shopping experience, where he helped to improve the Amazon website interface, including developing its book preview program. While Tesler enjoyed the job at Amazon, his wife had remained in Silicon Valley, and he also felt distant from venture capitalist
Venture capital (often abbreviated as VC) is a form of private equity financing that is provided by venture capital firms or funds to start-up company, startups, early-stage, and emerging companies that have been deemed to have high growth poten ...
s that were plentiful in Silicon Valley, and opted to leave Amazon. Tesler moved back to Silicon Valley in 2005 to join Yahoo!
Yahoo! (, styled yahoo''!'' in its logo) is an American web services provider. It is headquartered in Sunnyvale, California and operated by the namesake company Yahoo! Inc. (2017–present), Yahoo Inc., which is 90% owned by investment funds ma ...
as vice president of their User Experience and Design group. After three years, he found that Yahoo! had too many competing product lines and a lack of focus, and left in 2008. He worked for a year at the personal genetics information company 23andMe
23andMe Holding Co. is a publicly held personal genomics and biotechnology company based in South San Francisco, California. It is best known for providing a direct-to-consumer genetic testing service in which customers provide a saliva sample ...
as product fellow, before establishing himself as an independent consultant in December 2009 to help Silicon Valley companies with designing their user interfaces and experiences.
Personal life
After his first marriage ended in divorce in 1969, Tesler married Colleen Barton, a geophysicist.
Tesler had kept his countercultural attitudes beyond his early career, which he became known for at his other positions. He also maintained an attitude that being successful in Silicon Valley was a "rite of passage", and those who succeed should try to help fund new ventures and to educate others. The Computer History Museum
The Computer History Museum (CHM) is a museum of computer history, located in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the information age, and explores the computing revolution and its impact ...
, on Tesler's death, described Tesler as having "combined computer science training with a counterculture vision that computers should be for everyone".
Tesler maintained his strong preference for modeless software well beyond his time at PARC. To promote his preference, as of 1995, Tesler equipped his automobile with a personalized California license plate reading "NOMODES". Along with others, he had also been using the phrase "Don't Mode Me In" for years, as a rallying cry to eliminate or reduce modes usage.[ by Larry Tesler, Chris Espinosa] His personal website was located at "nomodes.com" and on Twitter
Twitter is an online social media and social networking service owned and operated by American company Twitter, Inc., on which users post and interact with 280-character-long messages known as "tweets". Registered users can post, like, and ...
had used the handle "@nomodes".
Tesler died in Portola Valley, California
Portola Valley is a List of municipalities in California, town in San Mateo County, California. Located on the San Francisco Peninsula in the San Francisco Bay Area, Bay Area, Portola Valley is a small, wealthy community nestled on the eastern ...
, on February 16, 2020, at the age of 74.
See also
*AI effect
:''For the magnitude of effect of a pesticide, see Pesticide application. Of change in farming practices, see Agricultural intensification.''
The AI effect occurs when onlookers discount the behavior of an artificial intelligence program by argui ...
*List of programmers
This is a list of programmers notable for their contributions to software, either as original author or architect, or for later additions. All entries must already have associated articles.
A
* Michael Abrash – program optimization and x8 ...
*List of computer scientists
This is a list of computer scientists, people who do work in computer science, in particular researchers and authors.
Some persons notable as programmers are included here because they work in research as well as program. A few of these people ...
*Law of conservation of complexity
The law of conservation of complexity, also known as Tesler's Law, or Waterbed Theory, is an adage in human–computer interaction stating that every application has an inherent amount of complexity that cannot be removed or hidden. Instead, it mus ...
References
External links
*
Publications by Larry Tesler
from Interaction-Design.org
* Computer History Museum
The Computer History Museum (CHM) is a museum of computer history, located in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the information age, and explores the computing revolution and its impact ...
, Larry Tesle
Oral History Interview
* Stagecast site
Founders
1999 Lecture on Novice Programming
Larry Tesler home page
from Interaction-Design.org
** Computer History Museum
The Computer History Museum (CHM) is a museum of computer history, located in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the information age, and explores the computing revolution and its impact ...
, Larry Tesle
Oral History Interview
** Stagecast site
*
Founders
*
1999 Lecture on Novice Programming
{{DEFAULTSORT:Tesler, Larry
1945 births
2020 deaths
American computer programmers
American computer scientists
Human–computer interaction researchers
Programming language designers
20th-century American scientists
21st-century American scientists
Scientists at PARC (company)
Scientists from New York (state)
Apple Inc. employees
The Bronx High School of Science alumni
Stanford University alumni
American Jews