Specifications

C–8 SROM Initialization
Subject to Change – 17 January 1997
Flash ROM Loading
C.7 Flash ROM Loading
Under normal conditions, the AlphaPC 164 loads and executes the second firmware
image that it finds in the flash. If jumper CF7 is installed, the first firmware image
will be loaded. This process begins with a search for the header signature beginning
at the first location in the flash.
Once the appropriate header is found, based on its ordinal position in the flash, the
header checksum is validated. If the header checksum is valid, the image is loaded
into memory based on the location specified in the header. If the header checksum is
not valid, the search continues until the first physically valid header is located. If no
header containing a proper checksum is located, the search repeats from the first
location in the flash ignoring header checksums.
While loading an image into memory, the image checksum is validated. If the image
checksum is valid, control is turned over to the loaded image, passing in the SROM
parameters defined by the firmware interface.
If the image checksum is not valid, the search continues as though this image did not
contain a valid header.
If no image containing a proper checksum is located, the search repeats from the first
location in the flash ignoring all checksums.
Then, if no image can be located in the flash, the entire flash is loaded and executed
starting at memory location zero.