In 1965, IBM was preparing to introduce their new product line, the System/360. They wanted to market this product towards both scientific and business communities. This meant they needed a new language with both floating point and decimal capabilities, and list processing. The result was PL/I. New innovations included: concurrent tasking, pointers included as a data type, cross sections of arrays could be referenced as vectors, and over 23 built-in exeception types.

Source: "Concepts of Programming Languages" by Robert W. Sebesta, The Benjamin/Cummings Publishing Company, Inc, 1993