Deficiencies in existing methods of music input have made the process slow and tedious; text music editors are difficult to use, graphical music editors are slow, and Optical Music Recognition is inaccurate and requires cumbersome equipment. This research aims to develop one of the fastest and easiest methods for entering music into computers-the pen-based music input. The design of pen music input closely follows the idea of traditional pencil and manuscript for musicians. Musicians draw sketches on the system similar to those they do on paper. The development of smaller and lighter low-cost pen computers enables the system to be portable. This thesis develops an earlier method for using pen computers to input music, called Presto. It extends the gesture set and further develops the system in Presto. The objectives of Presto are to be fast, easy to learn, easy to use, and portable. This thesis first reviews existing gesture sets and graphical music editors. Next, four aspects of Presto are investigated: gestures, editing features, drawing beams, and feedback. The research on each part reviews existing work on the relevant issues, then designs and implements improvements. Presto has become significantly faster than its previous version, and many features are improved to make it more usable. It can be three to more than four times faster than using other methods to input music. The research on the pen-based music input has greatly improved accuracy, functionality, speed, and usability of Presto, making it a useful technique for musicians.