This is a screen shot (at 1/4 actual size) of a BKStarLogo
world box. The program running simulates multiple Cleaning Robots
(we call them Clobots) shown in red or yellow, depending on their
cleaning state. The green clusters represent patches of dirt to
be cleaned. Clobots emit one of two signals or sounds, one when
they are over "dirt" and cleaning it (shown in yellow),
the other when they aren't (shown in red). Clobots listen for the
sounds and move toward ones emitting the "cleaning"
sound and away from those emitting the "non-cleaning"
sound. This "2-signal" method cleans areas with patches
or clusters of dirt faster than can be done by just randomly
wandering Clobots.
The MIT Media Lab has released its version of StartLogo for the PC. Their web site is StarLogo on the Web.
The
following is the General Help that comes with BKStarLogo v1.4.
BKStarLogo can be obtained as freeware. While our version is not as full
featured as the MIT version, it contains additions such as
turtles able to hear other turtles at a distance. E-mail us at bkserv@bellsouth.net for more information.
This program lets you create and run programs written in the StarLogo language. StarLogo was created by Mitchel Resnick and is an extension of the Logo programming language.
BK StarLogo is a simple Windows 95 version of StarLogo. As of April 1999, the only other working versions of StarLogo are for the Apple Macintosh. We attempted to make a system that lets users of PCs get a feel for StarLogo. [10/01: There is now a version of StarLogo available for PCs. Get it at http://el.www.media.mit.edu/people/starlogo/.]
StarLogo lets you write programs that cause "turtles" to move around a world covered with a grid of "patches". Each turtle follows the same instructions. The patches are active and can change the value of variables the programmer may give them. Turtles also can have user-defined variables. Turtles can change their own variables' values, and can change the variables' values of the patch they are on. They can also "sense" patch variable values. The language can be used to study how complex behavior emerges from simple rules. See the reference section for more information on StarLogo. Scroll ahead for information on the BKStarLogo dialect of StarLogo.
Loading, Saving, and Running BK StarLogo Programs
Click Load to load a SL file. You can double-click in the Program Box to increase it's size, double-click again to return to normal size. (This also works for the Info Box.) You can edit the program in the Program Box if you wish. Click Save to save the program to a SL file. Click Run to run the program. (You could also click 1 to execute the program 1 line at a time.) While the program is running, you can click Pause to pause it. While paused, you can click 1 to execute 1 line at a time. Click Stop when you want to stop running the program.
The BKStarLogo Language
All commands must end on the same line they start on. A line that starts with a single quote is a comment and is not executed. The world is by default set to a screen edge of 32, so there are 65 by 65 patches (from -32 to 32, including 0). Possible screen edge values are 16, 32, 64, and 128. If the screen edge is set to 16, you can set the shape of the turtles with the command:
set-shape shapefile
where shapefile is a 16 by 16 bitmap. Don't use the .bmp extension, just the file name.
When running a program, you can click on a patch to see it's coordinates, color, and the value of any patch variables. You can right-click on a turtle to see it's coordinates, color and the value of any turtle variables.
The system offers Help on each BK StarLogo command. You can scroll through the list of commands in the listbox below then click for Help on the command. Or if you put the cursor on the first character of a command in the Program Box and hit F1, info on that command will pop up.
There are many sample programs included with BKStarLogo. These are ASCII text files that have an extension of .SL. Load them into the BKStarLogo system and see what they do!
The StarLogo language was created by Mitchel Resnick who works at the MIT Media Lab. The language is fully described at the website StarLogo on the Web.
A recent article on StarLogo, titled "E Pluribus Unum", appears in the Jan/Feb 1999 Issue of American Scientist magazine. It gives a great introduction and overview to what StarLogo can do.
Mitchel Resnick wrote a book about StarLogo called TURTLES, TERMITES, AND TRAFFIC JAMS. It was published in 1994 by The MIT Press. A paperback version is available at Amazon.com.
If you have any comments or questions about BK StarLogo, please e-mail us at B K Services, Inc. by clicking on our e-mail address given above. We appreciate all comments. Let us know if you have any extensions to StarLogo that you would like to see us implement in future versions. We will try to add them in.
End of BK StarLogo General Help