The IBM System/370 Vector Architecture

Discussed is the instruction-set architecture of the IBM System/370 vector facility, a compatible extension of the System/370 architecture. Both the base system, which is a general-purpose System/370 processor, and the optional vector facility employ a register type of organization. Data formats are the same, arithmetic operations produce exactly the same results, arithmetic exceptions are handled in the same way, and instructions are precisely interruptible for page faults and other causes in the same manner as those of the base system. This approach permits substantially increased performance on vectorizable programs with only a modest increase in hardware and software, while retaining the ability to run existing nonvector programs unchanged.