link: https://www.ebay.com/itm/272987932493 Just finished checking it out by the manual, works fine! This little board is a 6-bit DAC, amplifier, and speaker on a little S-100 board, and allows your S-100 machine to make sounds. It's apparently pretty good for a 6-bit DAC, there are videos on YouTube of other hobbyists playing samples taken from various audio sources using the Model 6 -- at least, I was surprised that it sounded as good as it did. Set up for the default port of 0x24 and using the internal speaker. Don't really know what they're worth, so feel free to submit an offer! Thanks, Jonathan