CREATE TABLE table_name_57 (sspec_number VARCHAR, i_o_bus VARCHAR)

What's the sSpec number of the processor having an ultra-low power I/O?
SELECT sspec_number FROM table_name_57 WHERE i_o_bus = "ultra-low power"
SELECT "sspec_number" FROM "table_name_57" WHERE "i_o_bus" = "ultra-low power"