 PRISM was one of the first designs to include a multiply with add/subtract/truncate in a single (five operand) instruction, so it was often described as a three-issue CPU.The original PRISM design was introduced in 1988 in the one-to-four-CPU Apollo DN10000 workstations.The "DN" in the name refers to "Domain Node", Domain/OS being the Unix-like operating system used on all of Apollo's machines.