DATA TRACE DEVICE

PROBLEM TO BE SOLVED: To inexpensively realize a small trace function by constituting a data trace device so as to execute a data writing operation at higher speed than a reading operation and executing the refleshing of a dynamic memory for storing data which is outputted from a data storing means after the execution of the reading operation. SOLUTION: 'H' and 'L' are repeated in a select signal SEL so that data of a signal T2 to be traced is successively stored in the dynamic memory (DEAM) 14. Therefore, time difference occurs between the generation of a bus cycle in a target CPU 11 and transfer to DRAM 14 but the data of the signal T2 to be traced is stored in the generation order of the bus cycle. Moreover, the reading of small capacitance storage elements 12a and 12b is executed at high speed than writing so that refreshing is executed in an obtained surplustime. Therefore, inexpensive and small DRAM 14 is used as the memory for storing data to be traced.