| 摘要 |
<p>PURPOSE:To secure the same time information in entire CPU cards, and to obtain the time whose measuring unit is smaller and whose efficiency is high by having a common memory connected with a system bus, which stores the time information outputted by a clock. CONSTITUTION:A CPU 11 obtains the time information outputted from a real time clock 100, and judges whether or not access to a common memory 15 is possible. At that time, when the access to the common memory is possible, the access to the common memory 15 from the other devices is inhibited, and the time information outputted by the real time clock 100 is written in the common memory 15. Then, the inhibition of the access to the common memory 15 from the other devices is released, and the writing operation of the time information for the common memory 15 is ended. At the time of desiring to obtain the time information, a CPU 11a of a CPU card 1a judges whether or not the access to the common memory 15 is possible, inhibits the access to the memory 15 from the other devices when the access is possible and reads the time information.</p> |
