According to the design requirements and design content, explain the CPU model, and briefly introduce the internal resources and pin structure diagram of the selected CPU.TB9C2051 is a single chip microcomputer with 2K byte flashing programmable erasable read-only memory. The erasable read-only memory of the single chip microcomputer can be erased repeatedly 1000 times. The device is manufactured using ATMEL high-density nonvolatile memory manufacturing technology and is compatible with the industry-standard MCS-51 instruction set and Hanout pins. Due to the combination of multi-function 8-bit CPU and flash memory in a single chip, ATMEL's A851 is a high-efficiency emblem controller, and AT8C2051 is a simplified version of it. AT89S51 microcontroller provides a flexible and inexpensive solution for many embedded control systems. Figure 3-2-1 shows the outline and pin arrangement.