METHOD AND DEVICE FOR DECIDING NUMBER OF EMPTY MEMORY POSITION IN FIFO MEMORY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an improved technique deciding the number of empty memory positions in a FIFO memory device. SOLUTION: This FIFO memory device is provided with plural pieces of memory positions having sequential binary addresses, a write address pointer for sequentially making access to the memory positions for writing the data, and a read address pointer for sequentially making access to the memory positions for reading the data. According to this invention, an inverted write binary address of the write address pointer is added to the read binary address of the read address pointer, and 1 is added thereto, and also the most significant bit(MSB) is destroyed to decide the number of the empty memory positions.