缓冲器74hc541 3-state buffer inverter三态缓冲反向器74hc58 dual and or gate 与或门74hc589 3state 8bit shift 8位移位寄存三态输出74hc594 8bit shift reg 8位移位寄存器74hc595 8bit shift reg 8位移位寄存器出锁存74hc597 8bit shift reg 8位移位寄存器入锁存74hc620 3-state transceiver 反向3态收发器74hc623 3-state transceiver 八路三态收发器74hc640 3-state transceiver 反向3态收发器74hc643 3-state transceiver 八路三态收发器74hc646 non-invert bus transceiver 总线收发器74hc648 invert bus tranciver 反向总线收发器74hc688 8bit magnitude comparator 8位判决电路74hc7266 2-input exclusive nor