I am working on a design where in system upgrades through the serial port is essential. I would like to use an prom as bootcode, and write to a Flash lying in Xdata. A jump to an adress above 8000h (i guess) should trigger a flipflop, which makes the flash the code area, and a real sram the memory area.

Has anyone made such a design ( almost certainly ) and can you give me some schematics on this. Any experience in this matter (good and bad) will be appreciated.

Regards
Jes Ramsing