Hello All,

To explore the concept of external memory, I have planned to do a few experiments. Since now I have a fair idea about External Ram( http://www.8052.com/forum/read.phtml?id=72139 ).

I want to do some pratical experiments using external code.

I have planned to use a single external 32K NVRAM as Ext. RAM as well as Ext. ROM. After going through the previous messages (I found very few related messages). I have come up with the following design: Please note only key interface details with external memory are shown, all other components are not shown.



All the 12k code of AT89S53 will be used up.
The basic routines will be stored in this on chip flash.

Depending upon certain preconditions, the external NVRAM will be rewritten, using MOVX commands. The system is restarted.

After bootup, executing all the initialization routines in the onchip flash it jumps to the external code. the same code that was written in the NVRAM.

During RUN time can I move in and out on AT89S53 (code memory). Will the above mentioned circuit serve my purpose.

Or are there any other better methods.

If any more information is required, please let me know.

Regards
Raj