the hardware format is a cartridge with a cassette inside of it, enabling TAPESTREAM.
the music is recorded to the cassette part of the cartridge and is read thru the chip inside.
basically CDDA but for this form of media.
the chip can read both A + B sides depending what side the cart is on.
the cartridge can hold up to 16MiB of data and 60 MIN of music.
this means that there is only 30 MIN of music and 8 MB on one side.
usually a game will tell you to turn the other side towards you, this enables B-SIDE.
the devs can have the option to not do that by getting ahold of a special cartridge.
the special cart is called a ONE-SIDE cassette and can be toggled with a flag during intialization.