Hi, I am new to N79E059A 40 pin DIP package. This controller has 4k Data EEprom for storing or reading the data. I am able to write to data eeprom. Any guidance on writing the data flash will be helpful.
Writing twice to the same location of a flash memory is expected to fail, since the flash block needs to be erased before it is possible to write different information to it.
Note that ISP is In System Programming. So you can from the outside of the system program the memory without removing the chip. Sometimes by connecting a programming probe but now normally by connecting to some form of serial port on the hardware.
IAP on the other hand is In Application Programming. Which means that your running program can run commands that will change the contents of the memory.
So ISP documentation will not help you if the goal is to perform IAP. And if it's flash memory, then there should be some information about how to prepare a flash block so it is ready for new data.