This article uses two practical CNC systems as examples to illustrate the design methods and connection relationships of CNC systems, revealing their internal structure and how they control peripherals, and explaining how mechanics and electronics are combined. The JBNC320 CNC lathe is mainly used to machine rotating parts. These machining processes require the CNC system to: control the spindle's forward and reverse rotation and emergency stop; enable the tool post to achieve longitudinal and transverse feed movements and automatically change four positions at the tool change point to select the tool; enable automatic start and stop of the coolant pump; ensure that when machining threads, the tool post can move one lead Tmm of the machined thread for every one rotation of the spindle; enable linear and circular fillet operations; and provide overtravel protection, etc. This means that for a CNC system to meet the requirements of the machining process, it must be able to control the machine tool's main motion, feed motion, and auxiliary motion. To this end, we have successively developed the BKC-V type and BKC-VIII type CNC systems. First, we introduce the design of the BKC-V type CNC system. 1. Design of BKC-V type CNC coefficient As shown in Figure 1, the system mainly consists of a central processing unit 8031 ​​microcontroller, a read-only memory 2764 (8K×8), a static memory 6264 (8K×8), a programmable interface chip 8155, a programmable keyboard, and a display interface chip 8279. (1) Selection of CPU [b][align=center]For details, please click: JBNC320 CNC lathe CNC system design[/align][/b]