Based on original documents, this article deals with the first stored program computer designed and built in Belgium in the early 1950’s, the Machine Mathématique IRSIA-FNRS (MMIF). After addressing the history of this prototype, it describes the Machine and highlights its specificities. Then, showing how the computing techniques that led to this machine were originally disseminated in Belgium, it underlines the Swiss (particularly Eidgenŏssische Technische Hochschule (ETH)) influence on this project.