Eating Toast: 50 years of MASCOT from single core to diverse, distributed multicore systems

As mentioned in Paul Caseley’s 2025 talk, MASCOT went from sliced bread to toast. However, MASCOT has not died and after fifty-odd years is still being used in brand new products. MASCOT provides an excellent way to understand, and reason over, multithreaded systems. After introducing all the required symbology in a single slide, we will give a brief look at the history of MASCOT. This talk will discuss its evolution and on-going use within MBDA. We will look at its use within high integrity projects and cover its migration from paper-based designs, to bespoke tooling and COTS MBSE tools.

As a functional design tool, MASCOT went out of favour. However, we discuss its increasing relevance today. As we move into a world of multi-processor, multicore, distributed systems, MASCOT’s native handling of coordinated parallel processing with strong data segregation provides a great supplement to other design methodologies. We will cover the latest evolution, which involves “code generation time” mapping of threads to executables, and automatic assignment of inter thread communications to arbitrary transport layers.