The cT Programming Language Archives

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Brief history of cT

The cT programming language was developed in the period 1985-2000 in the Center for Design of Educational Computing at Carnegie Mellon University in Pittsburgh (the Center was later renamed the Center for Innovation in Learning; it ceased operation in 2002). The developers were David Andersen, Bruce Sherwood, Judith Sherwood, and Kevin Whitley. The initial impetus was the need for an easy to use graphics- and mouse-oriented programming environment for faculty and students using the then-new "3M" Unix workstations (a million bytes of memory, a million pixels, and a million instruction per second).

Ease of use was important because the alternative, writing in C and using highly complex graphics libraries, was beyond the capabilities of most users. Another issue was that at that time the windowing software was changing rapidly, so that programs written in C that used graphics or the mouse quickly became obsolete. Moreover, it soon became clear that not everyone would use Unix workstations, thanks to the increasing capabilities of the popular microcomputers, especially Macintosh and IBM PC. This put a premium on cross-platform executability of graphics programs, which C did not offer but cT did.

cT was based on earlier languages used by the authors of computer-based educational materials written for the PLATO computer-based education system developed at the University of Illinois at Urbana-Champaign. cT is a granddaughter of the TUTOR language initiated in 1967, and a daughter of the MicroTutor language initiated in 1977. cT differs from the earlier dialects in being designed for the modern graphical user interface (windows and mouse). Here is a reproduction of the textbook The TUTOR Language written in 1977 by Bruce Sherwood.

cT was used for a variety of purposes, but its main niche was the creation of programs for education. Many prize-winning educational programs were written in cT, especially in the area of physics.

In the fall of 1997 Ruth Chabay and Bruce Sherwood taught cT to students in an introductory physics class at Carnegie Mellon, and students used cT to model physical systems with graphical animations of system behavior. Thanks to its ease of use, it was possible in a mere hour or two to teach an adequate subset of cT to students for the purposes of the physics course, even for the many students who had never written a computer program before.

This approach was repeated in the fall of 1998. In the course was a freshman computer science student named David Scherer. In the following year he was looking for an interesting project to work on and proposed creating an alternative programming environment for students to use in the physics course. His hope was to make the programming even easier for novices, yet make it feasible for them to create real-time navigable 3D animations, whereas cT offered only 2D graphics. Assisted by David Andersen, Ruth Chabay, Ari Heitner, Ian Peters, and Bruce Sherwood, in the spring and summer of 2000 Scherer produced the VPython programming environment which was deployed in the fall 2000 physics course. The clear superiority of VPython with its easy to use object-oriented 3D graphics led to the decision to stop development of cT and concentrate on VPython.

Archived here are versions of the cT programming environment for Windows, Macintosh, and Linux, plus the public-domain source code for these environments. No support is currently available for these materials, but you are free to do whatever you like with them.

Further information:

vpython.org   Download VPython

glowscript.org A 3D programming environment similar to VPython, but runs in a browser

matterandinteractions.org   Information on the physics curriculum

Translated into Serbo-Croatian by Jovana Milutinovich

Translated into Russian by Ivanka Skakun

Later translation into Russian by Olga Fedorova

Translation into Belarussian by Vicky Rotarova

Translation into Ukrainian by Milana Sharapova

Translation into Polish by Science for Everyone

Translation into Lithuanian by Sergey Ivanov

Translation into Greek by Nikolaos Zinas

Translation into Macedonian by Katerina Nestiv

Translation into Indonesian by Jordan Silasen

Translation into Romanian by Irina Vasilescu

Translation into Thai by Ashna Bhatt

Translation into Uzbek by Sherali Niyazova

Translation into Georgian by Ana Mirilashvili

Tranlation into Japanese by Jianhua Ma

Translation into Kazakh by Alan Kerimova

Translation into Spanish by Suan Brown ( https://partituki.com/susan/)

Overview of cT

You should not start using cT now, because it is no longer supported. See vpython.org instead. The following materials are made available as an archive with historical interest.

The cT programming language is an algorithmic language like C, Pascal, Fortran, and Basic, but greatly enhanced by multimedia capabilities, including easy-to-use support for color graphics, mouse interactions, and even movies in QuickTime or Video for Windows format.

The cT programming language offers easy

programmability of multimedia programs, with
portability across Macintosh, Windows, Linux, and Unix.

The cT programming environment offers

on-line help with executable program examples,
a graphics editor for automatic generation of graphics commands,
incremental compiling to provide rapid turn-around, and
detailed error diagnosis.

cT was developed in the Center for Innovation in Learning at Carnegie Mellon University in Pittsburgh by David Andersen, Bruce Sherwood, Judith Sherwood, and Kevin Whitley. cT is a trademark of Carnegie Mellon University.

1. When is (was) cT the right tool?
2. Major features of the cT language
3. Major features of the cT programming environment
4. Obtaining cT at no cost
5. Sample Programs Included with cT
6. cT References

When is (was) cT the right tool?

It would not be prudent to start using cT now, when it is no longer being supported. The following materials are made available as an archive with historical interest.

There are many excellent applications available for creating pictures and diagrams, and for making multimedia presentations, without having to write your own computer program.

However, it is sometimes the case that doing something really new and different is hard to do with these non-programming applications, because they often don't provide enough control of interactions and enough calculational capability to do what you really want to do.

cT offers the open-ended flexibility and power associated with programming languages but eliminates many of the difficulties and complexities usually associated with using a programming language.

Major features of the cT language

• interactive graphics in windowed environments
• instant portability across Macintosh, Windows, Linux, and Unix
• support for QuickTime and Video for Windows
• animation of bitmap images
• color support for palette color and true color
• built-in support for buttons, sliders, and scrolling text panels
• multi-font text and character-string variables
• "hot" text (for hypertext applications)
• pull-down menus
• mouse and keyset inputs
• optional rescaling of text and graphics to fit the window
• analysis of words and sentences
• analysis of numbers and algebraic expressions
• rich sequencing options
• standard calculational capabilities
• numeric and text files

Major features of the cT programming environment

• integrated editing and execution environment
• incremental compilation for fast revision and execution
• on-line reference manual with executable examples
• graphics editor which generates cT graphics statements
• accurate and informative error diagnostics
• an extensive suite of sample programs in source form

Obtaining cT

Download cT 3.0 at no cost for Windows, Macintosh, or Linux: Click here to view the license agreement and download cT.

Programs written in cT run compatibly on all these machines, with no changes required. All that is needed is to transfer the file and compile it.

cT formerly was distributed by Physics Academic Software, whom we thank for their professional work on behalf of cT. Vastly expanded use of the World Wide Web has made it now appropriate to try a network distribution mechanism.

Sample Programs Included with cT 3.0

Here are descriptions of the cT programs available from the cT download page to give you  ideas for your own work:

General

• sample -- This program is a sampler of many of the basic capabilities of cT: color graphics, animations, pull-down menus, mouse clicks and drags, multi-font text, "hot" text, calculations, graphing of functions, and response analysis. After running the program you might want to study the program code to see how the effects are achieved.
• exercise -- A set of exercises to help you learn the basic concepts of programming in cT. The program contains a number of incomplete units with suggestions on how to complete them. The cT help contains the information needed to do these exercises.
• editfile -- A more complex version of the example discussed in "A File Editor Application". The editfile.t version reads and writes styled files containing multiple sections (that is, created with multiple dataout-s).
• showicon -- A program that displays the icons in an icon file. This can be useful in selecting icon numbers for use in a plot, move, cursor, or pattern command.
• icon -- A program for designing icons, cursors, and patterns, except on the Macintosh, for which the program Icon Maker is supplied.
• japan -- This program displays Japanese "Kanji" characters, using a set of icons "KANJI18.FCT".

Graphics

• draw -- A basic drawing editor, with many of the features of commercial drawing editors, such as grouping objects together, applying patterns, colors, and arrowheads, and designing your own palette of colors. Drawings are saved in the form of cT source code, so you may find draw.t useful in creating portions of your own programs, including color palette commands. This program also illustrates one approach to "object-oriented" programming in cT.
• map -- A little program which displays a map of the 48 contiguous states of the United States, with an ability to zoom in and out.

Color

• palette -- A use file which provides a set of useful additional colors beyond the basic eight cT colors, including dark red, dark green, and light, regular, and dark versions of slate, teal, coral, gray, gold, lavender, and cerise.
• setcolor -- A use file which lets you experiment with the color of an object, in the full context of your running program. This is useful for deciding exactly what color the object should be in relationship to other elements of your display.
• chaos -- A plot of the chaos in a simple population growth scheme. Usually what is plotted is just the final-state population. This program uses hues from blue to red to show the approach to the final state. The red dots correspond to the usual plot.
• spiro -- Make geometrical color designs by choosing the total number of vertices and the number of vertices to skip. It uses the use-file colorpic.t.

Video

• video -- A program which gives an example of how to build your own special-purpose video controller, using the basic video commands. This file can be used as a use file by other programs. A short video clip for testing purposes is provided for Macintosh and Windows.

Games

• BigForty -- A solitaire card game which uses touch regions, so that event-handling routines are driven automatically; there are no pause commands in the program. The program uses the use file animate to provide the option of sliding cards smoothly over the background on sufficiently fast computers.
• rilato -- A Mah Jong-like game in which you match corresponding pairs of tiles. Pairs can be chemical elements and their symbols, American presidents and their years in office, English kings and their years of reign, or American states and their capital cities. You can also create your own lists of pairs.

Physics and Math

• grapher -- Solves and graphs systems of algebraic or ordinary differential equations. This program was a first prize winner in the 1990 Educational Software Contest of the journal Computers in Physics (Sept./Oct. 1990, p. 540). The program includes an interactive explanation of how to use the program.
• hill -- Draw a hill with the mouse, place a block on the hill, give it an initial speed, and watch it move. If there is a valley, the block may move back and forth forever (no friction), or slowly come to rest (if you add some friction with the slider control). While the block moves, bar graphs display the kinetic, potential, and total energy. At the beginning of the program, the program makes a measurement to determine the animation step size, so the animation runs at about the same speed on fast and slow computers.
• orbit -- Launch a satellite near two stationary "earths," and watch the unusual orbits that result. At the end of the file is a 4th-order Runge-Kutta numerical integration procedure which may be useful in other contexts.
• optics -- Place lens and mirrors along a bench, then flash a light. Rays spread out and are bent by the optical elements, producing a spot on a piece of film. There is an interactive explanation of how to use the program.
• quantumw -- Study the quantum behavior of an electron in various kinds of potential wells. If the well is symmetrical, the bound states have symmetrical wave functions.
• sonar and voltage -- Simple examples of microcomputer-based-laboratory software. Connect a Universal Lab Interface (ULI) and Sonic Ranger (distributed by Vernier Software of Portland, Oregon, phone 503-297-5317) to the serial port of either a Macintosh or an MS-DOS machine, and sonar will track your motion in front of the motion detector. If you don't have this equipment, use the mouse to make motions that are graphed on the screen. The program voltage uses the ULI to plot voltage as a function of time.
• xyplot -- Plot a function of two variables, f(x,y), using a set of icons of differing dot densities (icon file random).

Inter-computer programs using sockets

• InterDraw -- Run this program on two different Macintoshes in the same AppleTalk zone, or two different Unix workstations on the same network (provided that a cT server has been established), and two people can draw on each other's screens, or run two copies of the program on one Unix workstation. This program is a simple example of the use of the socket command to link separate programs together.
• Battleship -- The classic "battleship" game played on two different Macintoshes in the same AppleTalk zone, or two networked Unix workstations (provided that a cT server has been established). This is another example of the use of the socket command. It also provides another example of how to do object-oriented programming in cT. The program uses the icons file SHIPicn.

cT References

• The March/April 1993 issue of the journal "Computers in Physics" (p. 136) contains an article by Bruce Sherwood and David Andersen describing cT and various applications written in cT.
• A discussion of some of the issues related to machine independence may be found in an article by David Andersen and Bruce Sherwood in the November 1991 issue of Byte Magazine (p. 221).

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