JPS5739458A - Operation history memory device - Google Patents

Abstract

PURPOSE:To read out effective words in order from the oldest in the words written in former times, by comparing contents of a write register with those of a start register, and completing read-out at the time of coincidence, in case when a start address register is read out as increment. CONSTITUTION:In accordance with a write instruction, contents of a write address register 16 become A+1 from A by counter 18, and at the same time contents of a write data buffer register 13 in that case are stored in the address A of a memory circuit. Then, increment and write are executed in order until an operation command is generated. Subsequently, in accordance with a read-out instruction, a start address register 17 passes through an address register 15, is provided to a memory circuit 12, and contents of B-1 address are read out to a read-out buffer register 14. Then, the address B is read out in the same way, the start address register 17 becomes B+1, and when it coincides with the register 16, a signal showing that the address B is final is outputted from a comparing circuit 20, and a read-out end signal and the contents of the address B are outputted.