Methods and structure for customizable BIOS in a peripheral device adapter. The controller of a peripheral device adapter senses a selection indicative of a desired customized BIOS configuration. BIOS information is updated to reflect the desired customized selection. In one embodiment, customization may be by updating portions of a default BIOS configuration with updated information stored in a selected custom BIOS information element. In another embodiment, each custom BIOS information element may store an entire snapshot of BIOS information customized for a particular application. The selected custom BIOS information may then be copied to a BIOS memory or BIOS memory accesses may be mapped to the selected custom BIOS information element.