hello, I have just started using Keil-c51 Eval version 7.50 with uVision for 8051 comptible device.I wanted to use 71M6513 from TDK.But unable to find it from Device Database i have selected closest match 73S11xx . My simple piece of code lookes like: #include <stdio.h> #include <string.h> #include <ctype.h> #include <Reg51.h> void foo() { unsigned char xdata x[10]; unsigned int xdata y[10]; unsigned char xdata z[10]; unsigned char xdata k[10]; unsigned long xdata d; x[3]=0x07; y[3]=0x0302; d=&y[3]; z[3]=0x09; k[3]=0x10; } void main() { foo(); printf("hello"); } I have configured XDATA start as 0x0000 and size as 0x1000...as the XDATA size for the particular device is 4kBytes. Now this program compiles OK. When go for step by step Debugging with uVision...and check the local variables there are two doubts come into my mind .They are: a) for the line d=&y[3] in source code above the result is d=X:0x00010010 ,why the adress of a xdata variable is crossing its maximum limit(max possible limit 64K also) ? b) When Xdata variable can adress upto 64Kbytes i.e 0xFFFF then why Xdata variable e.g x[10] in above source code shows starting address of X:0x00000000 i.e 4bytes why not X:0x0000 2bytes as i feel.?? I will be thankful if any one can pls take some time and clarify me on above two Qs. Thanks in advance, Arup