This application note describes the three methods that can be used to program the Flash code memory of the 89C51Rx+/Rx2/66x families of microcontrollers. It discusses in detail the operation of the In-System Programming (ISP) capability which allows these microcontrollers to be programmed while mounted in the end product. These microcontrollers also have an In-Application Programming (IAP) capability which allows them to be programmed under firmware control of the embedded application. This capability is also described
