IBM's first large-scale digital calculating machine, the Selective Sequence
Electronic Calculator (SSEC), is announced. The SSEC is the first computer that
can modify a stored program, and featured 12,000 vacuum tubes and 21,000
electromechanical relays.
IBM introduces the IBM 604 Electronic Calculating Punch. The mass-produced 604
features the industry's first assemblage of digital electronics replaceable as a
unit. Service engineers can simply pull out a defective unit of the 604 and plug
in a replacement, reducing downtime.
