Not until 1945 did the term computer begin to refer to a machine. Before that, a computer was a person, for some reason generally female, who solved equations and did calculations by hand or, more often, using a mechanical calculator and a slide rule.
People as computers, although no longer referred to by that name, survived for many years after the invention of the electronic computer.
In 1965, I worked at the Special Projects Laboratory at the Zinc Corporation in Broken Hill, New South Wales. After a day running our experimental equipment, we would spend the next day, sometimes longer, calculating the results.
Two of us, using different technologies, performed the calculations. One sat at a desk, using an electromechanical calculator to do addition and subtraction while scribbling down the interim results. The other person, standing behind the desk so that he could read the interim results, would use a slide rule to do the necessary multiplications and divisions. Then the interim results from the slide rule were written down so that they could used for the next set of additions and subtractions. After a while, we switched positions.
It all took a very long time. Because of the intrinsic limits on the accuracy of a slide rule, as well as the lack of a printed record to catch input errors, the accuracy and precision of the results was usually OK but no better than that. Ensuring quality required that the calculations be repeated to check their accuracy.
Had a personal computer been available, running an early spreadsheet such as VisiCalc, only one person would have been needed. Work that formerly required two man days could have been completed in an hour or two with greater accuracy.
Those who long for the "good old days" neglect the fact that highly qualified scientists and engineers spent far too much of their time just performing very routine calculations. If they did not do the calculations themselves, then they were expensively supported by a small army of living and breathing "computers".
There are few recent innovations that have contributed as much to increased productivity - and therefore wealth - than the invention of the electronic computer and the demise of its flesh and blood predecessor.