Abstract: An equipment for execution of maintenance operations in a multi-unit processing system one of which is a central unit comprises, in each unit, shift registers each made of a hardware series connection of multi-bit and single-bit register members which are parts of the unit and which, for part of them, copy the conditions of parts of the unit, and a local automaton for actuation and control of said shift registers, and a common maintenance station having command and data exchange facilities with the said local automatons. Each local automaton includes means responsive to local and remote commands for controlling read-out and write-in operations of said shift registers, interrupts of the operation of the unit and test and diagnosis routine executions by the said unit from the data in the said shift registers.