This article was originally published October 5, 1984.A battered, white step-truck rattled to a stop near the corner of Fourth Street and Martin Luthur King Jr. Avenue in Southeast Washington. For a moment it sat quietly in the noon sun as newly fallen leaves crackled in their race with a breeze.Then, suddenly there was a rude blast of sound:"Get your back up off the wall, dance, come on!" a recorded voice shouted in a syncopated rhythm that bolted from a storm of multi-percussion beats, synthesized beeps, explosions and quick-jabbing R&B horn lines.The music blared from tinny speakers, blanketing the area's littered streets, its neat and not-so-neat little houses and storefront businesses. In the process, hundreds of students from nearby Ballou Senior High School were drawn to the step-truck that sells cookies, sodas and ice-cream from a window behind bars. Some danced, doing the "Happy Feet," to the beat. Many just nodded in time as they munched on 45-cent chili dogs and sipped soda."Michael Jackson is all right, but this is the best," said Marcus Johnson, 16, who was within earshot of a parked car that, too, was loud with the same type of music pouring from its cassette tape deck: "I feel like bustin' loose, bustin' loose . . . "The music seems to be everywhere: sang, played and carried in oversized, shoulder-mounted tape players and radios in every quadrant of the nation's capital. The music, with its broken melody lines and chants urging one to "rock your butt, y'all," can be heard at metro stops, city parks and playgrounds where school girls jump rope to its beat.It's "go-go" music, and it is the District's own -- rough, aggressive, urban and black.