Extended CP/M-86 (V1.1A) 1983 Digital Research MS-DOS v2.11 (MZ-6550 V1.1A) 1983 Microsoft MS-DOS v2.11 (MZ-6500 V2.0A) 1983 Microsoft MS-DOS v2.11 (MZ-5500 V1.0A) 1983 Microsoft MS-DOS v2.11 (MZ-5500 V1.1A) 1983 Microsoft