DATA STORAGE AMOUNT MONITORING DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent malfunctions also relating to the case that the clocks for write and read to/from a memory are asynchronous at any speed difference and to monitor the amount of non-read data stored in the memory in real time. SOLUTION: A write counter register 11 generates a write address when the data are written to the memory 9 and a read counter register 12 outputs a read address for which the read address synchronized with the read clock when the data are read from the memory is synchronized with the write clock asynchronous with the read clock at any speed difference. A differential circuit 17 performs arithmetic processing from the write address and the read address synchronized with the write clock and obtains the data stored inside the memory and a register 18 holds them by the write clock and outputs storage amount data.