Preheat oven to 350°F (175°C).

Grease the bottom of an 8 1/2 x 4 1/2 x 2 1/2-inch loaf pan.

In a mixing bowl, combine self-rising cornmeal, all-purpose flour, sugar, and buttermilk.

Stir until smooth.

Let the batter rest for 20 minutes.

Stir the batter lightly.

Pour the batter into the prepared loaf pan.

Bake for 1 hour, or until a toothpick inserted into the center comes out clean.

Cool in the pan for 10 minutes before removing.

Turn the cornbread out onto a wire rack to cool completely before serving.