The ILLIAC IV was the first massively parallel computer. The system was originally designed to have 256 64-bit floating point units (FPUs) and four central processing units (CPUs) able to process 1 billion operations per second. Due to budget constraints, only a single "quadrant" with 64 FPUs and a single CPU was built. Since the FPUs all had to process the same instruction – ADD, SUB etc. – in modern terminology the design would be considered to be single instruction, multiple data, or SIMD.