| 摘要 |
A data monitoring and recording system particularly for vehicles, includes a real-time clock circuit 62 (Figs. 2, 5) which supplies 16 Hz pulses, derived from a crystal controlled oscillator by a frequency divider network 102 (Fig. 5), to a computer module 50 (Fig. 2) for real timekeeping purposes. In addition, the divider network supplies pulses at 1 p.p.m. to a counter 112 in the clock circuit. When the computer module 50 is operative, one or more memory locations in a data memory 54 provide the real timekeeping function. When the computer 50 is turned OFF, e.g. when the vehicle engine and power supply 60 are turned OFF, these data locations are no longer operative. However information is retained therein by a stand-by battery 64 which also supplies the clock circuit at this time. The counter 112 accumulates minute pulses during the OFF period of the supply 60 and when this supply is restored the accumulated count in counter 112 is added to up-date real time counters in the data memory 54. <IMAGE> |
