Importance

Loading Importance Indicators...

Abstract

A fail-safe flash for an EPROM that is arranged into separately erasable sectors proceeds in a stepwise procedure. The EPROM is divided into at least three regions including a boot block region, a file region and a directory region. The boot block region stores at least two independently erasable boot blocks, only one of which is designated as a current boot block, which performs scanning of the directory region so as to determine a current directory in the directory region. The file region stores all executables, including executables designated as critical and non-critical. The directory region stores multiple directories, only one of which is a current directory, which designates which is the current boot block, which of the files stored in the file region are available for loading for execution, as well as which of the files are critical and which are non-critical. In the first step to flash the EPROM, the unused region of the boot block is updated with the new boot block. In the second step of flashing the EPROM, critical files are flashed over non-critical files, and after correct installation of the newly-flashed critical files is confirmed, a new directory is written into the directory region referring only to the newly-flashed critical files. In the third step of flashing the EPROM, non-critical files are flashed, whereafter a new directory is written to the directory region referring to the newly-flashed critical files as well as to the newly-flashed non-critical files.

Loading the Abstract Image...

First Claim