HOCUS stands for Hand Or Computer Universal Simulator.
It is a discrete-event simulation system used in Operations Research that was specifically designed to be dual-purpose: models can be run either by hand using physical tokens or on a computer.
Key features of the HOCUS system include:
- Activity Cycle Diagrams (ACDs): Users first sketch a diagram showing how entities (like people or machines) move between active states and idle queues.
- Manual Simulation: The system allows for a “hand” simulation where the user moves markers around the diagram to understand logic and verify the model before moving to a computer.
- Computer Implementation: Once verified, the manual logic is translated into data (originally using punched cards) for execution on various computer platforms.
- Origin: It was developed in the 1960s by Robin Hills and popularised by the P-E Consulting Group.
The important aspect of HOCUS was the ‘manual simulation’ which ensured the analyst understood what was actually happening rather than it all being part of some opaque ‘black box’ where the learning was around the syntax of operation and not the principles of operation.