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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
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Moments that changed communities, movements, institutions and the nation.
In 1968 Shirley Chisholm became the first Black woman elected to the United States Congress. In 1972 she launched a campaign for the Democratic presidential nomination, breaking another political barrier.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
| Logo | |
|---|---|
 L-system (Koch curve) turtle graphic | |
| Paradigms | Multi-paradigm: functional, educational, procedural, reflective |
| Family | Lisp |
| Designed by | Wally Feurzeig, Seymour Papert, Cynthia Solomon |
| Developer | Bolt, Beranek and Newman |
| First appeared | 1967 |
| Typing discipline | Dynamic |
| Website | el |
| Major implementations | |
| UCBLogo, many others | |
| Dialects | |
| StarLogo, NetLogo and AppleLogo | |
| Influenced by | |
| Lisp | |
| Influenced | |
| AgentSheets, NetLogo, Smalltalk, Etoys, Scratch, Microsoft Small Basic, KTurtle, REBOL, Boxer | |
Logo is an educational programming language, designed in 1967 by Wally Feurzeig, Seymour Papert, and Cynthia Solomon.[1] The name was coined by Feurzeig while he was at Bolt, Beranek and Newman,[2] and derives from the Greek logos, meaning 'word' or 'thought'.
A general-purpose language, Logo is widely known for its use of turtle graphics, in which commands for movement and drawing produced line or vector graphics, either on screen or with a small robot termed a turtle. The language was conceived to teach concepts of programming related to Lisp and only later to enable what Papert called "body-syntonic reasoning", where students could understand, predict, and reason about the turtle's motion by imagining what they would do if they were the turtle. There are substantial differences among the many dialects of Logo, and the situation is confused by the regular appearance of turtle graphics programs that are named Logo.
Logo is a multi-paradigm adaptation and dialect of Lisp, a functional programming language.[3] There is no standard Logo, but UCBLogo has the facilities for handling lists, files, I/O, and recursion in scripts, and can be used to teach all computer science concepts, as UC Berkeley lecturer Brian Harvey did in his Computer Science Logo Style trilogy.[4]
Logo is usually an interpreted language, although compiled Logo dialects (such as Lhogho and Liogo) have been developed. Logo is not case-sensitive but retains the case used for formatting purposes.
Logo was created in 1967 at Bolt, Beranek and Newman (BBN), a Cambridge, Massachusetts, research firm, by Wally Feurzeig, Cynthia Solomon, and Seymour Papert.[5] Its intellectual roots are in artificial intelligence, mathematical logic and developmental psychology. For the first four years of Logo research, development, and teaching work was done at BBN. The first implementation of Logo, called Ghost, was written in LISP on a PDP-1. The goal was to create a mathematical land where children could play with words and sentences.[6] Modeled on LISP, the design goals of Logo included accessible power[clarification needed] and informative error messages. The use of virtual turtles allowed for immediate visual feedback and debugging of graphic programming.
The first working Logo turtle robot was created in 1969. A display turtle preceded the physical floor turtle. Modern Logo has not changed very much from the basic concepts predating the first turtle. The first turtle was a tethered floor roamer, not radio-controlled or Wireless. At BBN, Paul Wexelblat developed a turtle named Irving that had touch sensors and could move forward, backwards, rotate, and ding its bell. The earliest year-long school users of Logo were in 1968–69 at Muzzey Jr. High in Lexington, Massachusetts. The virtual and physical turtles were first used by fifth-graders at the Bridge School in the same city in 1970–71.
Logo's most-known feature is the turtle (derived originally from a robot of the same name),[5] an on-screen "cursor" that shows output from commands for movement and a small retractable pen, together producing line graphics. It has traditionally been displayed either as a triangle or a turtle icon (though it can be represented by any icon). Turtle graphics were added to the Logo language by Seymour Papert in the late 1960s to support Papert's version of the turtle robot, a simple robot controlled from the user's workstation that is designed to carry out the drawing functions assigned to it using a small retractable pen set into or attached to the robot's body.
As a practical matter, the use of turtle geometry instead of a more traditional model mimics the actual movement logic of the turtle robot. The turtle moves with commands that are relative to its own position, LEFT 90 means spin left by 90 degrees. Some Logo implementations, particularly those that allow the use of concurrency and multiple turtles, support collision detection and allow the user to redefine the appearance of the turtle cursor, essentially allowing the Logo turtles to function as sprites.
Turtle geometry is also sometimes used in environments other than Logo as an alternative to a strictly coordinate-addressed graphics system. For instance, the idea of turtle graphics is also useful in Lindenmayer system for generating fractals.
Some modern derivatives of Logo allow thousands of independently moving turtles. There are two popular implementations: Massachusetts Institute of Technology's StarLogo and Northwestern University Center for Connected Learning's (CCL) NetLogo. They allow exploring emergent phenomena and come with many experiments in social studies, biology, physics, and other areas. NetLogo is widely used in agent-based simulation in the biological and social sciences.
Although there is no agreed-upon standard, there is a broad consensus on core aspects of the language. In March 2020, there were 308 implementations and dialects of Logo, each with its own strengths.[8] Most of those 308 are no longer in wide use, but many are still under development. Commercial implementations widely used in schools include MicroWorlds Logo and Imagine Logo.
Legacy and current implementations include:
Logo was a primary influence on the Smalltalk programming language. It is also the main influence on the Etoys educational programming environment and language, which is essentially a Logo variant written in Squeak (itself a variant of Smalltalk). Logo influenced the procedure/method model in AgentSheets and AgentCubes to program agents similar to the notion of a turtle in Logo. Logo provided the underlying language for Boxer. Boxer was developed at University of California, Berkeley and MIT and is based on a literacy model, making it easier to use for nontechnical people.[30]
KTurtle is a variation of Logo implemented at Qt for the KDE environment loosely based on Logo.[31]
Two more results of Logo's influence are Kojo, a variant of Scala, and Scratch, a visual, drag-and-drop language which runs in a web browser.
[…] Dr. Logo first appeared on the retail market in the fall of 1983 for the IBM PC and climbed to the top of the Softsel Hot List. The retail release included SpeedStart CP/M, an abridged version of CP/M that boots automatically when the system is turned on. […][1]
Media related to Logo (programming language) at Wikimedia Commons
Logo Programming at Wikibooks| Classic | |
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| With object extensions |
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
Logo is an educational programming language, designed in 1967 by Wally Feurzeig, Seymour Papert, and Cynthia Solomon. The name was coined by Feurzeig while he was at Bolt, Beranek and Newman, and derives from the Greek logos, meaning 'word' or 'thought'. A general-purpose language, Logo is widely known for its use of turtle graphics, in which commands for movement and drawing produced line or vector graphics, either on screen or with a small robot termed a turtle. The language was conceived to teach concepts of programming related to Lisp and only later to enable what Papert called "body-syntonic reasoning", where students could understand, predict, and reason about the turtle's motion by imagining what they would do if they were the turtle. There are substantial differences among the many dialects of Logo, and the situation is confused by the regular appearance of turtle graphics programs that are named Logo. Logo is a multi-paradigm adaptation and dialect of Lisp, a functional programming language. There is no standard Logo, but UCBLogo has the facilities for handling lists, files, I/O, and recursion in scripts, and can be used to teach all computer science concepts, as UC Berkeley lecturer Brian Harvey did in his Computer Science Logo Style trilogy. Logo is usually an interpreted language, although compiled Logo dialects (such as Lhogho and Liogo) have been developed. Logo is not case-sensitive but retains the case used for formatting purposes.
Lisp (historically LISP, an abbreviation of "list processing") is a family of programming languages with a long history and a distinctive, fully parenthesized prefix notation. Originally specified in the late 1950s, it is the second-oldest high-level programming language still in common use, after Fortran. Lisp has changed since its early days, and many dialects have existed over its history. Today, the best-known general-purpose Lisp dialects are Common Lisp, Scheme, Racket, and Clojure. Lisp was originally created as a practical mathematical notation for computer programs, influenced by (though not originally derived from) the notation of Alonzo Church's lambda calculus. It quickly became a favored programming language for artificial intelligence (AI) research. As one of the earliest programming languages, Lisp pioneered many ideas in computer science, including tree data structures, automatic storage management, dynamic typing, conditionals, higher-order functions, recursion, the self-hosting compiler, and the read–eval–print loop. The name LISP derives from "List Processor". Linked lists are one of Lisp's major data structures, and Lisp source code is made of lists. Thus, Lisp programs can manipulate source code as a data structure, giving rise to the macro systems that allow programmers to create new syntax or new domain-specific languages embedded in Lisp. The interchangeability of code and data gives Lisp its instantly recognizable syntax. All program code is written as s-expressions, or parenthesized lists. A function call or syntactic form is written as a list with the function or operator's name first, and the arguments following; for instance, a function f that takes three arguments would be called as (f arg1 arg2 arg3).
In computer programming, variadic templates or variation generics are templates that take a variable number of type parameters. They exist in several programming languages and are used for the creation of type-safe generics with a variable number of types. They are somewhat similar in nature to variadic functions or variadic macros. Variadic templates are supported by C++ (since the C++11 standard), and the D programming language. While other languages, such as Java or C# offer support for type-safe variadic functions, they do not offer the variadic generics support like that of C++ and D.
C is a general-purpose programming language created in 1972 by Dennis Ritchie. By design, C gives programmers relatively direct access to the features of typical CPU architectures, customized for the target instruction set. It has been and continues to be used to implement operating systems (especially kernels), device drivers, and protocol stacks, though its use in application software is decreasing. C is used on computers ranging from supercomputers to microcontrollers and embedded systems. C was initially developed as a successor to the B programming language at Bell Labs by Ritchie between 1972 and 1973. Its initial purpose was to construct utilities running on Unix, and was later applied to re-implementing the kernel of the Unix operating system. During the 1980s, C gradually gained popularity, leading to it becoming one of the most widely used programming languages, with C compilers available for practically all modern computer architectures and operating systems. The book The C Programming Language, co-authored by the original language designer, served for many years as the de facto standard for the language. C has been standardized since 1989 by the American National Standards Institute (ANSI) and, subsequently, jointly by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). C is an imperative procedural language, supporting structured programming, lexical variable scope, and recursion, with a static type system. It was designed to be compiled to provide low-level access to memory and language constructs that map efficiently to machine instructions, all with minimal runtime support. Despite its low-level capabilities, the language was designed to encourage cross-platform programming. A standards-compliant C program written with portability in mind can be compiled for a wide variety of computer platforms and operating systems with few changes to its source code. Although neither C nor its standard library provide some popular features found in other languages, it is flexible enough to support them. For example, object orientation and garbage collection are provided by external libraries GLib Object System and Boehm garbage collector, respectively. Since 2000, C has typically ranked as the most or second-most popular language in the TIOBE index.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Brown v. Board of Education in 1954.
