| 摘要 |
PURPOSE:To speed up a machine cycle in a system including a semiconductor memory device and to optimize a system constitution by selectively connecting input/output (I/O) circuits and I/O terminals and setting up an array selecting circuit to a prescribed selecting condition to change the constitution of words. CONSTITUTION:A static type RAM sets up the channel of the array selecting circuit ASEL to a prescribed connecting state and I/O circuits I01-I04 and I/O terminals DI01-DI04 corresponding to the connecting state are selectively connected. Thereby, three kinds of word constitution, i.e. m.n. words X bits, 2.m.n words X 2 bits or 4.m.n words X 1 bit, can be adopted. In any word constitution, the static type RAM can be controlled by a single phase start control signal (clock), the inverse of CE. Consequently, effective word constitution appropriate for the system can be selected based on a basic mask pattern, the memory cycle of the system can be speeded up and the machine cycle can be shortened.
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