sentence: despite the difficulty of doing so , numerous asynchronous cpus have been built , including : the ordvac and the ( identical ) illiac i ( 1951 ) the johnniac ( 1953 ) the weizac ( 1955 ) the illiac ii ( 1962 ) the victoria university of manchester built atlas the honeywell cpus 6180 ( 1972 ) and series 60 level 68 ( 1981 ) upon which multics ran asynchronously the caltech asynchronous microprocessor , the world-first asynchronous microprocessor ( 1988 ) ; the arm - implementing amulet ( 1993 and 2000 ) ; the asynchronous implementation of mips r3000 , dubbed ( 1998 ) ; several versions of the xap processor experimented with different asynchronous design styles : a bundled data xap , a 1-of-4 xap , and a 1-of-2 ( dual-rail ) xap ( 2003 ?