A counter is efficiently implemented in non-volatile memory by using two binary counters and selectively using one or the other as a current counter. In embodiments, a bookmark is received from a client device at a media content service. The wireless terminal determines a maximum data size for navigation information to be downloaded. An excitation efficiency of the first luminescent conversion element is higher than that of the second luminescent conversion element. When an over current situation is measured, the circuit will automatically shut down to protect the device’s electronic components.