Hi Roberto,

Indeed, 80C390 has internal SRAM.
But it's NonVolatile, only and only if you want to put the micro in Stop Mode,
with band gap select or not (100 uA down to 1 uA) and supply the micro with backup battery.
Otherwise, the internal SRAM will behave like any ordinary external SRAM. Will lose contents due to lack of power supply.
Yes, you are right that loading a program into micro it's possible to change the contents of an external non volatile memory starting with location 0x00000.
80C390 has this ability to configure its 4kB of internal SRAM as combined program and data memory. It will never act like EEPROM, FLASH or PEROM.

In my opinion, as stated before, Martin was a little bit confused about the definition of /CEs, called program chip enable.
He believe that this pins could enable programing the internal memory program.
Obvious it is not any trace of ordinary internal Flash, EEprom or whatever could be called, inside 80C390.
Definitely it's inside 89C420, 87C550, but not in 80C390 manufactured by Dallas.

If he wish using 4Kb internal SRAM like a loader and want to know how could be done, this is another story.

Best regards,
Silviu