Tapuino is a full playback datassette emulator. Tapuino does not require an external tape playback device or digital audio player. Rather, the Tapuino hosts a SD card reader and the entire device attaches directly to the C64’s cassette port for both 5v power and C64 data bus access. Individual .TAP files are stored on a SD card. From the C64’s perspective this device is indistinguishable from a real datasette. As a result, any Commodore computer with a tape port can use this device.
Design for the SMD version is from here.