Atari Logo — Atari Computers

Learning by moving a turtle

Atari Logo, developed by Logo Computer Systems, Inc., treats programming as an interactive exploration. Commands move a turtle across the screen, while named procedures build larger ideas from small steps. The Atari version adds multiple turtles and facilities for sound and interaction.

Example: draw a square

With the English-language Atari Logo cartridge running, type these commands at the prompt. CLEARSCREEN clears the drawing area, SHOWTURTLE makes the turtle visible, and PENDOWN ensures that movement draws a line.

Atari Logo — immediate turtle commands

CLEARSCREEN
SHOWTURTLE
PENDOWN
REPEAT 4 [FORWARD 50 RIGHT 90]

Expected result: a 50-step squareIllustrative preview

The turtle draws four equal sides, returning to its starting position facing upward. The command area is omitted to focus on the drawing. Colors and turtle shape are approximate, using Logo’s startup blue background and gold pen. Atari Logo turtle-graphics manual.

Each repetition draws one side and turns a right angle. Changing the distance changes the square’s size. Commands inside the brackets form an instruction list, a central Logo idea.

Give the drawing a name

Type the following definition, ending with END, and then call ATARISQUARE from the prompt. Logo remembers the procedure for reuse during the session.

Atari Logo — a reusable procedure

TO ATARISQUARE
REPEAT 4 [FORWARD 35 RIGHT 90]
END

ATARISQUARE

Expected result: a smaller square joins the firstIllustrative preview

Run immediately after the first example, ATARISQUARE adds a 35-step square at the same starting corner. It does not clear the previous drawing. On a cleared screen, only the smaller square appears. Colors and turtle shape are approximate, using Logo’s startup blue background and gold pen. Atari Logo turtle-graphics manual.

Reference: Atari Logo Reference Manual (PDF).