Method and apparatus for transfer of data between cache and flash memory in an internal combustion engine control system

Abstract

In a microprocessor-based automotive control system including flash memory and a RAM cache sized substantially smaller than the storage capacity of the flash memory, a caching technique is operable, in accordance with one aspect of the invention, to move areas of the flash memory into and out of the cache. The flash memory is updated by the contents of the cache each time the a new access is attempted to an area of flash memory or after a predefined time period has elapsed since such an access has been attempted. In accordance with another aspect of the invention, 9 bit storage within the flash memory is disallowed and only word (16 bit) or longword (32 bit) storage is allowed therein, so that the flash memory is addressable only on even boundaries thereof. A software algorithm is operable to modify a request for access to an odd flash memory address so that the request properly points to an address of the cache that contains the actual data of interest.

Dependencies are inferred from the claim text.