A process of programming or reprogramming a reprogrammable onboard memory (5) comprises programming or reprogramming the onboard memory of several modules (M0, M1) in parallel through a multiple access bus (6) to which the modules are connected. In the case of blank flash memories, a process downloads code through the multiple access bus (6) and executes the code, eliminating all external constraints (such as frequency, binary throughput). The process is more particularly intended to apply to onboard flash type memories.