Take a look at this site:
**broken link removed**
In the "How To" box on the left side of the page find the sections for "Olsen 595" and "Dimming the Olsen 595". There is also links to a PIC derivative system titled "Renard" hosted on another site.
Cheap, fast and relatively easy to do exactly what you want using parallel port and bit banging it. Since you are skilled in the programming end, should be a piece of cake, but they also have software links for sequencing the light displays to music files.
Quote:
have heard that newer computers can be set up to read the data lines as well as right. If you find out how to do that, let me know. Otherwise you have to read 4 bits at a time on the status register.
Easiest way to do this is in EPP mode. You can read/write all 8 data bits, with simple programming , using only hardware based instruction decoding, and do it quite fast.