In this paper, the development of an integrated starter alternator (ISA) system is described. The main system components are an induction machine drive system supplied by a high-voltage dc bus with ultracapacitor support and a high power dc/dc converter. The control of the induction machine, dc/dc converter and the overall supervisory control algorithm implemented on the ADMC330 DSP, are described. Having developed a functional integrated starter alternator, the relative merits of the technology are assessed. A comparison is made with a conventional starter motor during cranking. Timing diagrams illustrating DSP signals for an engine start-up sequence are also presented.