This is a simulation of Apple II LOGO, a programming language developed by MIT's AI lab in the 1960s. The triangle in the middle of the screen is called a turtle. To get started click on the GREEN FLAG. You should get a "WELCOME TO LOGO" message. Now you are ready to start.
To move the turtle you type commands into the command line which has a ? and flashing cursor next to it. Start with something simple like
Type F D SPACEBAR 1 0 0 PAGE DOWN or DOWN ARROW. The PAGE DOWN is like "RETURN". It is very important to have the space between the D and the 1, otherwise you will get a I DON'T KNOW HOW TO FD100 message.
After you hit PAGE DOWN the turtle will move forward 100 turtle steps and leave a line behind him.
To draw a square type the following series of commands remembering to hit PAGE DOWN after each one.
RT 90 FD 100 RT 90 FD 100 RT 90 FD 100 RT 90
You have a square!
If you make a mistake don't worry, just hit the LEFT ARROW to delete or PAGE DOWN and see what happens. Also remember to wait for the ? to come back before typing.
FD 100 is Forward 100, moves the turtle forward 100 steps. BK 100 is Backward 100 RT 90 is Right 90, turns the turtle right 90 degrees. LT 90 is Left 90 HOME clears the screen and send the turtle to the 0,0 position. PU is Pen Up this stops the turtle from drawing. PD is Pen Down this starts the turtle drawing. CS is Clear Screen this removes the drawing from the screen REPEAT 4 [FD 100] is a loop that repeats the step FD 100 four times. To get the [ type PAGE UP N and to get ] type PAGE DOWN M (think of Page Up as "shift"). Hit PAGE DOWN to run the command.
To write a simple script. You can type
and hit PAGE DOWN. This will put you in the "edit" mode (note there is no ?). You can then type
FD 100 RT 90 SQ END
with PAGE DOWN after each line. Typing END ends the script and takes you out of the edit mode.
At the ? you can then type SQ
You have a program of a square!
Note that this is what Seymore Papert called a recursive program - which means that it goes forever! Unfortunately, to stop it you have to start again and you will lose the program.