Core issue
The %Error formatting slot0 (Can not find flash algorithm) error message is received when the format slot0 command is issued. The reason is that the advanced technology attachment (ATA) flash is referenced as disk0, and not as slot0. If the filesize of the Flash memory is greater than 20 MB, it is considered a disk and not referenced as a slot.
Resolution
Issue the format disk0: command instead of the format slot0 command.
Refer to the Catalyst 6500 Series Supervisor Engine Flash PC Card Installation Note section of Catalyst 6000 Family Flash Card Install Note for more information.