because in Keil's monitor deskription is said, that monitor must reside in external ROM
Unless the Keil monitor require a specific hardware design, this does not make sense, the '51 does not "know" whether the fetch is from internal or external ROM.

i am not sure but i think if code is executed frmo internal ROM no MOVC commands can be executed for external ROM
I can not imagine how screwy a design would have to be to make it so. There is no difference whatsoever between internal and external ROM as far as use.

As a monitorprogram stores the program to debug in external RAM also MOVC must address external RAM
This is NOT normal '51 operation.

Whether an instruction is executed from internal or internal ROM can be determined by 3 factors
The state of !EA
The derivative
The address

Erik