You might indeed have one with a bad ROR. My MOS documentation for the time says ROR would be "available" after "June, 1976." The Rev A here is 30th week 1976 a

You might indeed have one with a bad ROR. My MOS documentation for the time says ROR would be "available" after "June, 1976." The Rev A here is 30th week 1976 and does not have the bug.