In the 1930s, "computer" wasn't a thing, it was a job description. Insurance companies and banks employed thousands of people wielding mechanical calculators to balance spreadsheets and do what we take for granted with a single computer.

In the second half of the decade, a handful of the world's best minds (Konrad Zuse, Alan Turing, Howard Aiken) were designing electromechanical calculators, but the general public stayed ignorant. Things started to take off in 1939, and with the benefit of hindsight, it's fascinating to see what was being done. Bell Telephone was creating calculators for automatic telephone switching, universities were creating their own computing machines (University of Manchester, Iowa State University), and the World's Fair in New York gave inventors a chance to get publicity for their computing machines.