What is the functionality of the first computer?

Answer 1

1. The first programmable computers were analog computers. One of these was MIT's mechanical Differential Analyzer built in 1929. It was designed to solve differential equations.
2. One of the first programmable digital computers was the Harvard Mark I built in 1942. It could solve any mathematical problem that could fit in its registers. Programming was by multiple 24 channel punched paper tapes, permitting simple subroutines and function table lookup.
3. The first electronic digital computer was the Atanasoff-Berry Computer built in 1942. It could only solve systems of simultaneous equations up to 29 variables.
4. The first programmable electronic digital computer was the Colossus, 11 of which were built between 1943 and 1945. It could only crack messages sent in the Nazi Lorenz teletype Cypher, but studies after the war show that it could have also been programmed to solve mathematical problems but with minor difficulty.
5. The first programmable electronic digital computer that the general public was shown was ENIAC finished in november 1945. Modeled largely on the MIT Differential Analyzer and mechanical adding machines it could solve any mathematical problem that could fit in its registers. Like the Differential Analyzer it was programmed by rewiring its cables and setting hundreds of switches.