Oded Avraham wrote:
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Hi
How can I switch the program to start running from the RAM, after copying to it a program, and the Flash could be accessed as data memory.

I need a simple and chip interface between the 8051, Flash and RAM.

If I understand your question correctly, you want to able to use both the flash and the RAM as both program and data-memory.

To do that you have to and RD and PSEN so either of them can enable the outputs of the memory chips. You will also need an address decoder, so that only one chip will be selected at a time. If you only need to connect the two chips (and they are both <=32kB) you could use A15.

To execute a program from the RAM you just jump to the start address of the RAM (8000h if you use the A15 "decoder").

Best regards,

Mikkel C. Simonsen