| 摘要 |
<p>A real time clock apparatus (20) comprises a counter (23) which stores a count value, the count value representing a time signal. The counter (23) may be written, for example by a host processor (not shown), such that the time signal can be set to any desired value. The real time clock apparatus (20) comprises a check register (33) that stores a check value. The content of the check register (33) (i.e. the check value) is modified each time a write operation is performed on the counter (23). For example, the content of the check register (33) can be updated by a control signal (35) each time a write operation is performed on the counter (23). The check value stored in the check register (33) is used for determining whether a write operation performed on the counter (23) is an authorised write operation or an unauthorised write operation. The check value may be incremented each time a write operation is performed, replaced with a new random number each time a write operation is performed, or a combination of both.</p> |
