a system update protocol . a software update is packed into a packed file , which packed file includes a unique signature . the packed file is uploaded from a trusted client computer to the network printer . the integrity of the packed file is automatically checked on the network printer by performing a checksum and signature comparison to ensure the packed file is transmitted correctly . the packed file is resent when the packed file is determined to be corrupt . the packed file is unpacked into a predetermined directory structure of unpacked files . the client computer then signals the network printer cause installation of the software update on the network printer .