Abstract: A distributorless ignition system for an internal combustion engine includes one spark coil for cylinder of the engine, a first reference signal generator for producing a first signal indicative of each revolution of the engine, a second reference signal generator for producing a second signal indicative of every second revolution of the engine, and a processor for evaluating the advance and dwell angles of an ignition pulse to a selected spark coil determined from a logical combination of the first and second signals. During starting, the processor is arranged to operate in a dual-spark mode for the first revolution of the engine and produce two ignition pulses simultaneously for each first signal, one to each of two cylinders which are 360.degree. out of phase with each other. During running of the engine, the second reference signal generator is monitored and, if found to be faulty, the processor changes from a one-spark mode to a dual-spark mode.

Abstract: To increase the versatility of a central processing unit (30) controlling an operating apparatus, such as apparatus including an engine, installed in an automotive vehicle, a main read-only memory (ROM, 40) stores not only operating data of the vehicle and/or the engine, but additionally, the organization program of the central processing unit (CPU, 30) in modular, or block form in the ROM (40). An auxiliary ROM (41) preferably an electronically erasable ROM is connectable, via an interconnection bus (80) to the CPU (30) and an initial program stored in the main ROM (40) provides a determination or recognition step to be carried out by the CPU (30) first, to determine if the auxiliary EPROM (41) is present; and, if so, to then address the auxiliary EPROM (41) for control of the program run of the CPU; if not, to take programming operating data directly from the ROM (40).