ZX-TSid
Sound card for ZX Spectrum edge connector (ZX-BUS). Contains MOS SID, YM2149 (AY-3-8910) and covox.
Current status
Work in progress, both pcb and firmware isn't finished yet and may contain serious issues. Please note the errata for rev.A pcb.
SID
MOS-6581 or MOS-8580 may be installed, but with some cautions. This addon doesn't contain buffers between SID and bus connector, and that may cause SID's damage by ESD if no luck. As I have no real SID, I've checked this addon only with SwinSID.
SID accessible via #xxCF port, where xx - SID's register number.
YM2149 (AY-3-8910)
Accessible by TurboSound standard as a second sound chip. ABC or ACB stereo panning selectable with onboard jumpers.
Covox
Monophonic covox accessible via #xxFB port (Pentagon standard).
Line input
You may connect your ZX Spectrum audio output to second 3.5mm jack and it will be mixed in sound card output signal.
Compatibility
SID and Covox (theoretically) should work with any ZX Spectrum containing edge connector (48K, 128K, +3, clones, etc.). YM2149 uses IORQGE signal, which is incompletely implemented in original ZX Spectrums and most clones (such as Harlequin). Sizif-512 and Karabas-128 clones implements IORQGE in right way.