The LPC2470 has no flash. Wanted to know if the LPC2478 can drop in replace the LPC2470 and not use its on board flash? Is there something special we need to do with the LPC2478 to get it to not use its onboard flash?
LPC2470 is flashless version of LPC2478. they are pin to pin replacement.
theoretically, you use LPC2470 project directly on LPC2478.
yes, just make sure your LPC2478 board has the same PCB design as LPC2470.
LPC2470 project can work on LPC2478 directly.