In 1948, computing stood at a crossroads between electromechanical machines and new electronic systems. IBM introduced the Electronic Calculating Punch, type 604, a programmable calculator that offered electronic speed at a fraction of the cost and size. IBM 604 became highly successful with over 5600 units produced, renting for just $550 monthly.

The IBM 604 introduced pluggable modules that combined vacuum tubes with associated components, a significant design departure from previous chassis-mounted electronics. These patented modules allowed mass production, simplified maintenance through easy replacement, and packed components in three dimensions for greater density.

The system used about 1250 vacuum tubes, including specialized thyratron tubes that acted as high-current switches. Unlike regular tubes, thyratrons used xenon gas that ionized when activated, staying on until power was removed. This technology directly led to the IBM 650 in 1953, which became the most popular computer of the 1950s.