Who Invented the Computer?

1837. Charles Babbage describes a general purpose computer in brass and steam. It is never built, but every essential idea is here.

1843. Ada Lovelace publishes her notes on the unbuilt engine, including what is widely described as the first computer program, a framing itself debated.

1937 to 1942. Atanasoff and Berry build the first automatic electronic digital computer at Iowa State. It cannot be programmed, and that asterisk fuels the whole dispute.

1940. Alan Turing's 1939 design, refined by Gordon Welchman in 1940, breaks Enigma at Bletchley Park. Built on the Polish Cipher Bureau's own bomba kryptologiczna, and operated in numbers by servicewomen of the Women's Royal Naval Service whose individual work the era's secrecy kept unrecorded for decades.

1941. Konrad Zuse completes the Z3 in Germany, electromechanical and relay-based rather than electronic. Destroyed by Allied bombing in 1943 and little known outside Germany for decades, it barely figures in the era's Anglo-American priority disputes despite being shown Turing-complete in 1998.

1943. Tommy Flowers builds the first programmable electronic digital computer to break the Lorenz cipher, and Britain keeps it secret until the mid 1970s.

1944. Howard Aiken and IBM engineers deliver the Harvard Mark I. Aiken's own press release names himself sole inventor, an omission of IBM's engineering team documented as angering IBM chairman Thomas Watson. Grace Hopper is one of its first programmers.

1945. ENIAC claims the first general purpose title in public, until a 1973 court finds its builders derived the idea from Atanasoff. The dispute becomes case law.

21 June 1948. The Manchester Baby runs the first stored program: for the first time, software lives in memory beside its data. This is the shape computers still have.

1949. Maurice Wilkes's EDSAC runs its first programs at Cambridge on 6 May. The second stored-program computer to enter regular service, after the Manchester Mark 1 the month before, distinct from the Manchester Baby this trail already visits, which proved the principle but was a testbed, not a working service.

1951. Eckert and Mauchly's UNIVAC I goes to the Census Bureau, and on election night 1952 it calls Eisenhower's landslide at odds of 100 to 1. Computers go public.

1964. The System/360 family ends the era of one of a kind machines: one architecture, every size, programs that survive an upgrade. The industry takes its modern shape.