Architecture and software support in IBM S/390 Parallel Enterprise Servers for IEEE Floating-Point arithmetic

IEEE Binary Floating-Point is an industry-standard architecture. The IBM System/360™ hexadecimal floating-point architecture predates the IEEE standard and has been carried forward through the System/370™ to current System/390® processors. The growing importance of industry standards and floating-point combined to produce a need for IEEE Floating-Point on System/390. At the same time, customer investment in IBM floating-point had to be preserved. This paper describes the architecture, hardware, and software efforts that combined to produce a conforming implementation of IEEE Floating-Point on System/390 while retaining compatibility with the original IBM architecture.