1. In a computer system having a processor, a system memory, a flash memory, and a memory controller, a method comprising the steps of: loading a flash memory upgrade program containing a new flash memory image and a digital signature into a portion of said system memory; configuring said memory controller to limit said processor to accessing only said flash memory and said portion of said system memory; verifying said flash memory update program using said digital signature; and, updating said flash memory only if said flash memory upgrade program is authentic.