引言以往在设计数字电路时,总是使用各种标准的TTL或CMOS集成电路。现在已有各种各样标准的TTL和CMOS集成电路,包括门电路、触发器、寄存器、多路开关和译码器等等,使用它们可实现各种逻辑功能。但该方法有很多缺点:电路复杂、体积大、功耗高、系统可靠性低等。因此,在微处理机和微计算机问世后,开始用计算机的软件来完成各种逻辑功 Introduction In the past in the design of digital circuits, always use a variety of standard TTL or CMOS integrated circuits. A wide variety of standard TTL and CMOS integrated circuits, including gates, flip flops, registers, multiplexers and decoders, are now available for use with a variety of logic functions. But this method has many shortcomings: the circuit is complex, the volume is big, the power consumption is high, the system reliability is low and so on. Therefore, in the advent of microprocessors and micro-computers, began to use computer software to complete a variety of logical work