Real-time computer simulations allow frequency response testing of the system and also give the engineer a better ‘feel’ of the system response when he looks at the visual display. In this paper, a mathematical model based on the quasi-steady state assumption and the development of a ‘real-time digital’ computer simulation suitable for investigating transient system response have been described. A thermal capacity effect for the exhaust temperature and the influence of pulsating flow conditions at the turbine inlet have also been described. ‘Real-Time Digital’ operation was achieved on a time-sharing system by using an analogue computer as a real-time clock and as a signalling device. Good agreement between the predicted and the test-bed transient results, prediction of smoke and ‘real-time digital’ operation are three distinct features.