I think there is a bit confusion about the term emulating USB-ZIP or USB-FDD. 1) For me emulating USB-ZIP means (any device, such as this USB-pendrive) claims to be (real USB-ZIP). Or emulating USB-FDD means (any device, such as this USB-pendrive) claims to be (real USB-FDD). I suspect this real emulating can only be done on hardware / firmware level and is not possible for normal end users. So either you buy a device with this feature or not...
Sourdough is dough which has microorganisms (for example lactobacillus or yeast) from sourdough or sourdough starters, which are active or can be reactivited. With the addition of grain products and water, they are capable of continuous acid generation.
Sourdough is a dough containing a Lactobacillus culture in symbiotic combination with yeasts. It is one of the principal means of biological leavening in bread baking, the others using cultivated forms of yeast. It is important in baking rye-based breads, where yeast does not produce comparable results.