SEMICONDUCTOR MEMORY DEVICE

摘要

PURPOSE:To relieve the defect of a mask ROM by a method wherein an EEPROM is installed in the mask ROM. CONSTITUTION:Common data lines CDE 0 to 7 which constitute a memory array ARYE for an EEPROM and which are connected selectively in eight bit lines each are coupled to input terminals for corresponding unit read amplifiers in a main amplifier MA and coupled to output terminals for corresponding unit write amplifiers. The input terminals for the individual unit read amplifiers in the main amplifier MA are coupled to the corresponding common data lines CDE 0 to 7, and the output terminals are coupled to corresponding unit circuits in a data input/output circuit IO. The input terminals for the individual unit write amplifiers are coupled to the corresponding unit circuits for the data input/output circuit IO, and the output terminals are coupled to the corresponding common data lines CDE 0 to 7. Individual data input buffers in the data input/output circuit IO take in and hold pieces of write data which are supplied via data input/output terminals IO 0 to 7 when the EEPROM is in a write mode.