Program the world's first computer!
"First" is always difficult, especially in computers.
Here are some examples of early machines, draw your own conclusions.
The Harvard Mark I was electromechanical. It was fully capable of
running a complex calculation, with the program on punched card stock
separate from the data. This is where the term "Harvard machine" comes
from, referring to a machine where the program and data are in separate
memory.
The ABC (1939) was mostly electronic, including electronic storage with
mechanical access. But its program was, I believe, on a plugboard. It
was not as general purpose as, for instance, the Mark I.
The Colossus (1944?) was all electronic. It was very special purpose and
barely if at all programmable.
The Eniac (1946) was all electronic and general purpose. It was
programmed by plugging. It and the Harvard Mark I were decimal and a lot
like a bunch of adding machines cobbled together.
The SSEM (1948) was all electronic and general purpose (but extremely
small.) It was a true stored program machine. It was also binary.
The Univac I (1950) was all electronic, general purpose and generally
useful (and also decimal.) It was a commercially available computer,
unlike all the previous ones.
Paul Pierce