This is an Raspberry PI shield for the AY-3-8910 Audio chip used in old computer systems like the ZX Spectrum and Amstrad CPC.
Based on the excellent work from Vince Weaver (http://www.deater.net/weave/vmwprod/hardware/ay-3-8910/)
This shield works with some minor adjustments to Vince's software and supports dual-mono/stereo output using two AY chips(optional)