Powering up a module from the IBM 604: an electronic calculator from 1948

In 1948, IBM introduced the Electronic Calculating Punch (type 604), a more compact and affordable alternative to room-sized computers that used vacuum tubes to perform 60 operations per second and became one of the most popular calculators of its era with over 5,600 units sold. A key innovation of the 604 was its pluggable modules, which combined vacuum tubes with associated circuitry in standardized, mass-producible units that simplified maintenance and repair, establishing a design approach IBM would use in later computers.