I noticed a strange behavior that looks like a hardware bug on a whole
series of Intel 8051. The A15 address line
(P2.7) is always low no matter what you do.
It happened with processors with labels
like this:

P80C51BHP 3164
L5440443F
INTEL (c)1980

or
P80C51BHP 3164
L5431571F
INTEL (c)1980
I tested many processors of these series and A15 was stuck low ine everyone. Other bathces may have the problem too.
In 8051 made by other companies (i tested AMD, Philips, and Atmel) the A15 worked as expected.
Is it possible that every intel 8051 has such a basic flaw or I'm doing something wrong?