I am using the Cypress EZ-USB FX2 Development Board, the Keil 4K evaluation compiler and the Keil default Monitor 51. I have a question concerning the location of the segments in the main RAM. I have carried out various experiments, and it seems to me, that although the "main RAM" is VonNeumann wired, there is a "hardvard logic" which places the data in the "main RAM", therefore, code and xdata aren't mixed. So, when we create a program, which will be loaded in the "main RAM", is it that the program code is placed in one section of the "main RAM" memory; and the xdata placed in another section (both these sections being located in the "main RAM")? I also wondered if the code adresses which are displayed in uvision2, in the debugger mode, are the adresses of the code section of the memory, or the adresses of the "main RAM". For example, if I declare two segments as follows: XSEG at 85h CSEG at 85h What would be the adresses of each segment in the "main RAM"? I hope you will be anle to help me and I look forward to receiving your reply. Many thanks Patrice