System X circuit board from digital switching subsystem, 1980
1980
1980
2014
1855
1914-1918
1903-1920
1855
1846
1760-1772
1961-10-04
1965-11-18
1795
1820
1800-1830
1848-1903
1800-1830
1831
1781
1848
1998
1998
1794-03-03
1824-1830
1998
1997
1847-1923
1823-1871
1943-01-01
1943-01-01
1954-10-21
1943-01-01
1925-1960
1850-1920
1891-1920
1801-1900
1880-1910
1880-1910
1891-1920
1900-1914
1891-1930
1896-1930
1837-1851
1830-1850
1871-1900
1935-1950
1880-1920
1801-1900
1880-1920
1841-1900