
System X circuit board from digital switching subsystem, 1980
1980
1980
(1962); 1982
1981
1981
1981
2000-100 BCE
1980
1980
1981
1980
1839 (original); circa 1988 (replica)
1981
4000-2001 BCE
1903 (original); 1982 (model)
1981
circa 1980
1990-95
circa 1980
1980
1980
1981
1980s
1980
1980
1980
1980
1980
circa 3000 BCE
2000-400
2000-400
1981
1980
circa 1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
2000-1350
1970 and post 1989
1980
2000-1000