If your into vintage drum machines or drum machines in general, you will have undoubtedly heard of the Alesis HR-16. It was Alesis's first drum machine and has a massive following even 25 years later. But if you have become fed up or feel limited with the units built in sounds then the team over at BurnKit2600.com have a guide showing you how to burn some new ROMs with your own custom sounds on them.
Using a pair of 27C040 ICs and a burner, they take you through the process of converting your samples and loading them onto the ROM for use in the HR-16. Seems like a slightly long-winded process but the results definitely seem worth it.
UPDATE : Jan aka Wintermute from Cologne in Germany has created a software program called CEG (Custom Eprom Generator) which allows you to import your custom sound files, converts them and generates the custom ROM hex file. This makes the whole process a lot easier and faster. Check out the software at this link.