The A20 handler is IBM PCmemory manager software[?] providing HMA[?]. XMMs[?] usually provide this functionality. Named after the 21st address line (A20), controlling the access to HMA.
... from 1516-1556 -- officially as Charles I of Spain, although often referred to as Charles V ("Carlos Quinto" or "Carlos V") in Spain and Latin America. He was the son of ...