听力原文： Apple Computer Inc. introduced on Tuesday its first computer mouse with multiple but- tons, including four sensors and a tiny scroll ball. Although a departure from the company's traditional mouse, the 'Mighty Mouse' looks very similar to the single-button model Apple has long produced. The most obvious difference is the relatively tiny scroll ball at the mouse's head, which can move cursors diagonally as well as up and down across display screens and can be pressed to 'click' functions. Designers of the new Apple device wanted a scroll ball that was less obtrusive than other scroll balls and 'stayed out of the way' of users who chose not to use it, said David Moody, vice president of Macintosh hardware product marketing. What did Apple Computer Inc. introduce on Tuesday?