thank you for the information.
what the purpose is: i'll read-in data from the rs232 (usart), put it in external flash memory, after that, i can select with a user interface which part of the programmed flash memory must be put on the data bus, set it into a RAM and do some tests with it.
i'll found the pic18f87j11 microcontroller, it got a external memory bus and the features named above, i'll think i'am going to use that one for my design.
someone got some experience with this type of microcontroller ? every information is welcome ofcourse