DDC即直接数字控制(Direct Digital Control)。在计算机控制行业中,由于过去计算机价格昂贵,采用磁芯存储器使主机的可靠性很低,无法与常规仪表调节器竞争,曾一度使DDC控制濒于灭亡。六十年代后期,国外的一些DDC纷纷下马,一些大的计算机公司也先后退出了计算机控制领域。七十年代初期DDC在我国的化工、炼油行业里也曾盛行过一个时期,后来也不得不败下阵来。 DDC is Direct Digital Control. In the computer-controlled industry, DDC control was once on its way to extinction due to the high cost of computers in the past, the use of magnetic core memory to make the host less reliable and unable to compete with conventional instrument regulators. In the late 1960s, some foreign DDCs were dismissed one after another. Some large computer companies also quit the computer control field one after another. In the early seventies DDC in China’s chemical industry, oil refining industry has also been prevalent for a period of time, but also had to defeat.