I thought I was (more or less) an experienced programmer with processors without the internal RAM. I’ve been doing Intel 80x86 programming for a long time, and MC6800 / HC11 as well, and I know that it is unlikely (is it really?) that you buy a RAM module with a fractional number of KB: simply, number of bytes should be equal to 2 to the power of number of pins.

Now I can see that 8052 has some internal RAM (0000h-00ffh). I think that external RAM at these addresses (0000h-00ffh), because of overlapping with internal RAM at the same addresses isn’t used (at all?). On the other hand, this address space belongs to the external RAM too. Because the contents of the internal RAM is much more important (SFR…) what happens to external RAM at this addresses? Does it remain unused?

I’m sorry for any incorrectness in the lines above, if any. Can you help me, please?