Difference and significance between on chip RAM & on-chip XRAM

What is the exact difference between On-Chip RAM & On-Chip XRAM ? Is the means XRAM means only extended RAM? What is the significance of both?
Difference and significance between on chip RAM & on-chip XRAM

What is the exact difference between On-Chip RAM & On-Chip XRAM ? Is the means XRAM means only extended RAM? What is the significance of both?
Does Keil simulator fix pdata on on-chip XRAM page 0 if on-chip XRAM MCU present?

I build a C51 program and want to show someone else how the pdata variable is stores in C51. The result seemed there exit some problem. I found if I select non on-chip XRAM such as Philips P89C51, the...
Does Keil simulator fix pdata on on-chip XRAM page 0 if on-chip XRAM MCU present?

I build a C51 program and want to show someone else how the pdata variable is stores in C51. The result seemed there exit some problem. I found if I select non on-chip XRAM such as Philips P89C51, the...
how to access on chip and off-chip XRAM of p89c51rd2 in c

how to access on chip and off-chip XRAM of p89c51rd2 in c