The PD7566A is a product of the PD7554, 7564 sub-series which is a low-end, low-cost version of the PD7500 series microcomputers. This 4-bit single-chip microcomputer has fewer ports than the other products in the PD7500 series, in order to reduce the package size, and is especially ideal for temperature control applications, as well as for application systems, such as air conditioners, microwave ovens, refrigerators, rice cooker, washing machines, and cassette deck controllers. Some of the output pins for the microcomputer can be used to directly drive triacs and LEDs. In addition, various I/O circuits can be selected by mask options, so that the number of necessary external circuits can be significantly reduced. A detailed function description is provided in the following user's manual. Be sure to read this manual when designing your system. PD7556, 7566 User's Manual: IEM-1111D