what did computers do for people before the minicomputer?

scientific calculation, usually batch processing of programs to solve particular complex mathematical problems

doing complex calculations quickly (eg. election prediction)

a little timesharing--many people work directly with the computer at once--mostly typed text

storing and counting large amounts of information, accounting
large companies used them for billing
"do not fold, spindle or mutilate" it said on the punch card you got in your bill

computer programming was a specialized job, who should learn it?
IBM wrote programs for mid-sized companies

using a computer meant writing a program--use programming to tell the computer how to solve your problem.  Applications hadn't been invented yet.