Did you try to program hex from pc to pic3 and try led flashing? How did you put hex in pic1? How do you sending hex from pic1 to pic3? Do you have same subroutine for sending or...?
Hi,
What kind of microprocesor and OS you are use? If you use the ARM or MIPS with Linux, there are many bootloader for that.
The main function of bootloader is setup the initial task for the microprocessor, such as, initialize the RS232, Cache management register, MMU, GPIO pins for special function, and so on. Then, the bootloader bring up the Linux(or OS).
Seems you didn't understand what bootloader means.
According to AT89C51 data sheet:
The AT89C51 code memory array is programmed byte-by-byte
in either programming mode. To program any nonblank
byte in the on-chip Flash Memory, the entire memory
must be erased using the Chip Erase Mode.