An active device for a coded information arrangement, a method of supplying coded information thereto, and systems comprising such an active device.

摘要

To encode data in the memory (31) of an active tag device an uncoded signal at a first input (21) is divided (at 134) to produce a signal (W) of alternating logic value 'I' and 'O', which is fed to a coding input of the memory; the frequency division circuitry (134) is duplicated in a separate programming unit which supplies a clock signal to a second input (41) when the logic signal (W) has the same value as the next bit of code to be encoded. The signal (W) is preferably taken from an intermediate part of the frequency division circuitry (134). Further outputs from the frequency division circuitry (134) may also be supplied to a gate (171) of a memory protection circuit (410) to define a predel=termined pattern of pulses which must occur at the second input (41) before programming can occur.