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