US Patent 7239572 Multiport memory

This multiport memory has a memory hold circuit, a plurality of write circuits and read circuits, and a read/write capability regulating circuit. The read/write capability regulating circuit individually sets a write/read capability of each of the write/read circuits. The read/write capability regulating circuit determines, using an operating state determining circuit, the number of writing/reading times per unit time in accordance with an operating state of each of the read/write circuits. As the operating state determining circuit used is a noise amount detection circuit, an operation completion detecting circuit, or a potential fluctuation detecting circuit.