One thing that I am curious about for quite some time..
Let's say you Flash an ESP8266 module with a Firmware, for example AT v126.96.36.199 and SDK v2.2.1.
Are the AT and SDK parts like 2 software layers?
Meaning the AT Commands interpreter is a program, that calls code on a lower layer - the SDK?
And now a second question:
Let's say a few days later, you program the ESP8266 with Arduino IDE +ESP8266 Core,
with some program that you wrote.
What resides on the Flash memory now?
Is the AT Commands interpreter program gone - overridden by the program you created in Arduino IDE?
And is some version of SDK code (binary) still there? (If yes is there a way to know which version of SDK is it?