Hi Dario,

in my opinion a "very basic 8051 system" was only the 8051 device itself, since already RAM and I/O peripherals included.

So I assume, you mean external connected RAM as code space for fast program download and software developing. Then also some PIOs must be connected to return the lost port pins.

Forget it, this was a very outmoded technology.
Use modern ISP/IAP derivates, e.g. T89C51RD2, which can be reprogrammed very fast and also many times.


Peter