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
