hi im new to microcontrollers and i was wondering about how parallel programming of on chip flash memory works. I read the datasheets and documentation from philps on their 8051s but still confused. I understand many can be programmed using ISP with the boot loader, and some have ICP capability, to program themselves, but what I was wondering is how do the parallel programmers access the internal flash memory without a boot loader for serial communication. Is it through one of the ports connected to the internal bus, like clock in address, clock in data while certain pins high or low? Would the 8051 be powered on while programming? Basically I want to understand the process of writing code to internal memory. i realise every chip would have different voltages and timing algorithms, but how would you find this information, datasheet, maybe i didn't understand it? i realise isp is simpler but want to understand the nuts and bolts behind how they wrote the boot sector in the first place.