LogoWriter as a Major Implementation of the LOGO Language for the Elementary Curriculum

by Jim Andris

LogoWriter is a learning environment for the elementary school computer-based curriculum. Some educators carry LOGO-based applications into middle school and even high school. LogoWriter is a combination of programming language, word processor, graphics, animation, problem-solving tool and math tool.

Whenever one chooses New Page from the Contents Menu, ??? appears at the top, to indicate that a new LogoWriter file, or page, has been started. To name the page, type np "name and press ENTER. ESC will take you from the new page to the Contents Menu, where you can select any page or start another new one.

To begin with, it is well to understand that there are three functional areas when working with LogoWriter. There is the command center, not a part of a page, where instructions are typed. The front side of the page is where text is written and graphics are drawn. The flip side is where procedures are defined.

There are key strokes for moving between these three functional areas. CTRL-F toggles back and forth between the flip side and the front side of the page. CTRL-U moves the cursor up to the front side of the page, and CTRL-D moves the cursor down to the command center.

When the cursor is in the command center, LogoWriter accepts the standard LOGO commands, including the turtle graphic commands discussed in the preceding paper "LOGO as a Programming Langage for Educational Applications." However, there are significant improvements of LOGO in LogoWriter. For example, once a line is typed into the command center, one can always scroll back to it using the arrow keys. If the cursor is on a line, then it can be reexecuted without retyping the line just by pressing ENTER. To erase any line in the command center (or anywhere in LogoWriter), just place the cursor at the beginning of the line and strike F6.

Each page can contain a maximum of about 4000 characters, counting both front and flip sides. LogoWriter can be use as a simple word processor. Once the cursor is on the front side of the page, the arrow keys can be used to move it around, and both upper and lower case text can be entered and edited according to standard word processing conventions.

The flip side works also as a word processor, only the main purpose here is the composition of procedures in the LOGO language. Both word processors have the four functions select, copy, cut, and paste. These four functions use the first four function keys, F1, F2, F3 and F4.

For example, to select a section of text on either side of a page, place the cursor at the beginning, strike F1, and use the arrow keys to highlight just that portion that you wish to select. Then, you can either cut it (causing it to disappear), F2, or copy it (make an invisible copy), F3, and finally, paste as many copies as you wish anywhere by placing the cursor where you want the copy to go and pressing F4.

LogoWriter has a shapes page that allows for easy creation and inclusion of graphics, and also provides for animation. The shapes page can be selected from the Contents Menu, instead of an old or a new page. Once in the shapes page, one can see the available shapes. The turtle can put on a costume, adopting a different shape. For example, typing setsh 27 will cause the turtle to adopt the shape of a small racing car, while setsh 0 will put the turtle's old costume back on.

Actually, there are four turtles, but you can only see the default turtle, turtle 0, unless you inform the other turtles to listen. For example
tell [1 2] setsh 27 will put the sports car costume on turtles 1 and 2.

You can create your own shapes very simply. Select the shapes page from the Contents Menu and note which of the shapes are not previously defined. CTRL-F takes you to the flip side, where you can arrow through the shapes once at a time. Notice that on the flip side, you are in a Shapes Editor. By using the arrow keys you can move around to various pixels in the shape and by striking the space bar you can toggle the pixel on or off. Note that using the function keys F1, F2, F3 or F4 you can select, cut, copy or paste shapes just as you can text or program code.

Shapes provide a convenient means of simple animation in LogoWriter. For example, the following list of commands will cause a sports car to "race" across the screen.

setpos [-100 0]
put the cursor 100 units to the left and about midway down the page
home seth 90
put the turtle in home position and point it to the right
setsh 27 pu
put a sports car "costume" on the turtle and take the pen up
repeat 100 [fd 1]
move the car across the screen in short increments

We can even have different colored cars: setc 1, white, setc 2, aqua and setc 3, magenta. There are hundreds of other colors available in LogoWriter.

After we have a screen looking like we want, say, with a short story and a few turtle graphics or shapes stamped in place, we can print out the screen very simply. Just type printscreen in the command center, make sure your paper is rolled up in the printer and you will have your "hard copy" within a few seconds.

A Quick List of LogoWriter Command Strokes for the IBM

cursor down to command center
toggle to flip side and back to front side
stop a procedure from executing
cursor up to front side of page
next screen
previous screen

F1 select
F2 cut
F3 copy
F4 paste
F6 erase to end of line
F8 label
F9 move turtle with arrow keys
F10 help
fd 50
bk 30
setpos [-50 30]
set position
lt 20
rt 90
seth 180
set heading
pen down
pen up
pen erase
pen reverse
tell [0 1]
which turtles follow commands
reset graphics
clear command center
clear text
setc 3
set color
setbg 2
set background
setsh 27
fill an area with color
fill an area with a shape