DNC and CNC
直接数据控制和计算机数字控制

The development of numerical control was a significant achievement in batch and job shop manufacturing, from both a technological and a commercial viewpoint.
数控的发展在分批生产和小批量生产中有着重要意义，从技术和商业角度来说都有着重要意义
There have been two enhancements and extensions of NC technology, including:
数控有两方面的提高和扩展包括
Direct numerical control
直接数据控制
Computer numerical control
计算机数字控制
Direct numerical control can be defined as a manufacturing system in which a number of machines are controlled by a computer through direct connection and in real time.
直接数据控制定义为一个制造系统，一定数量的机床有一台计算机通过直接硬件连线实时控制。
The tape reader is omitted in DNC, thus relieving the system of its least reliable component. Instead of using the tape reader, the part program is transmitted to the machine tool directly from the computer memory.
相应的磁带播放机忽略在直接数控中，这样就消除系统中最不可靠的环节。不用磁带播放机而用电脑信息传给车床。
In principle, one computer can be used to control more than 100 separate machines. (One commercial DNC system during the 1970s boasted a control capability of up to 256 machine tools.) The DNC computer is designed to provide instructions to each machine tool on demand When the machine needs control commands, they are communicated to it immediately.
原则上说一台计算机可以控制100台独立机器。DNC系统在1970 年称为可控制26 台机床直接数控，DNC电脑设计成在需要的时候提供指令给每一台机床，当机床需要控制指令时，计算机立即发送指令给机床。