I don't wish to make this an attack on Peter, as he did what most people here seem to do, namely to respond with, "You don't need to know that!" and little else. The O/P didn't say which "derivate" he intended to use, probably because he wasn't using a "derivate" but, rather, was using the "real McCoy" though that didn't arise until his later post. The question posed was not about the AT89C51ED2 or any other 805x device, or even any other MCU at all, but a general question about microcontrollers and microprocessors in general, which anybody should have been able to answer.

Cyrille Ngassam said:

I want to train myself with adresses decoding from an embedded systems.

"
Please look on the data sheet of the derivate, which you want to use (e.g. AT89C51ED2).

Then you find the address ranges for the code Flash, for the io-ports and peripherals (SFRs), for the direct and indirect accessible SRAM and for the external mapped SRAM / data EEPROM.

All address decoding was already done inside the chip.

Peter
"
Not only is this answer inapplicable, but patently false. While the device in question decodes internal resources as all MCU's do, it does no external bus decoding, which is what the O/P asked about. Since he intended his question to be generic, he didn't specify that it was the demultiplexed address bus, particularly since his interests extend to other processor types.

Kai Klass, after some time, did, in fact pick up on that, and respond to the original question.

If you don't like the opinions I spout, then you're welcome to ignore them. I don't think it's fair to ask Craig to do a bunch of work just because you don't want to do that. I think his effort would better be put into a spell-checker.

RE