Abstract: The operation of analog circuit blocks is simulated on a digital computer by a computer program in which each analog circuit block is represented by a procedure call including details of input signal name(s) and value(s), output signal name(s) and value(s), the operating parameters for the block and the sampling instant for the evaluation of the or each output signal value. The interconnections between blocks are represented by the use of the same signal names. Each sampling instant indicates when the value of an output signal will have changed by a predetermined amount since the previous sampling instant. A common sampling time is used for the circuit and is selected as the earliest of the sampling instants of the circuit blocks. The simulation can include digital circuit blocks represented by an event-driven or a levelised compiled code model, with analog/digital conversion to handle the interconnections between analog and digital circuit blocks.