Type the program in exactly as shown for a quick demo of your computer's sound capability. The program uses all three voices for it's rendition of what should be a very familiar tune. After studying the code you can figure out how to change the data statements and a few key constants to program your own song. Each of the data statements contains seven values. The first is the duration for the note to played. Three pairs of numbers specifying the frequency each of the voices will be for that note follow. Each voice has two bytes for controlling the frequency, in each pair the 'low byte' is followed by the 'high byte'. Your User's guide contains some note values in appen x L.
The last two data statements should be left intact. Line 670 zeroes the frequencies. Line 700 contains a single number for zero duration which signals to the program that the end of data has been reached. If your song requires more data statements, insert them before line 670. Lines 100-290 are for the most part a general purpose driver for sequencing the data statements that follow into the SID chip to create sound.
Another sound program called Organ, that I downloaded from the CBM Programming IG's B-128 database on Compuserve, provides the ability to 'play' songs using the top two rows of keys on your keyboard as a two octave organ keyboard. It also will play two songs that it comes with. The listing follows.
