Also Stratus: Wikipedia says they were originally built around M68Ks. The WP article is a bit thin on Stratus's early products, but my vague recollection is tha

Also Stratus: Wikipedia says they were originally built around M68Ks. The WP article is a bit thin on Stratus's early products, but my vague recollection is that they used 3 processors in lockstep, with voting to detect a faulty processor.