Fully optical TAPs do not have internal memory or any electronic components and are strictly a pass-through wherein a copy of the data is made. TAPs with any copper connections have two distinct and separate memory stores.
The two memory stores are non-volatile memory and volatile memory. They are not connected in any way and no data can move between them. The non-volatile memory provides certain functions that make the device work and cannot be modified or changed during normal operation of the device. Volatile memory holds network data as it is copied and passed through the device. Turning off the device clears any data in the volatile memory buffer.