Using bootloader is the most convenient way for PIC programming, especially when you are debugging your program and need to transfer it to the target PIC chip many times in short time. The hardware request is that there is a serial communication interface implemented between the target PIC board and the PC. The bootloader solution presented here is intended to be used with 18F452 microcontroller. As all other bootloaders, this solution consists of a Windows application running on the PC and bootloader firmware running on the target PIC chip. With minor modification of the CONFIG.TXT file, the bootloader can be used with many other models from PIC18F family. For example, for 18F4520 model, 'programblock:8' should be replaced with 'programblock:32'.
Windows application for downloading HEX files to the target PIC chip running the bootloader can be downloaded here.
The bootloader firmware is given in the form of Basic source program that has to be compiled with PIC18 Simulator IDE integrated Basic compiler to get the HEX file ready to be programmed into the microcontroller. The correct microcontroller model needs to be selected - 18F452, and the selected clock frequency is supposed to be at least 8MHz.