In this fourth instalment of the series we will look at our first applications of the ISAC cube and the simple motherboard, which will give a good introduction to the possibilities of the device. Complete example programs developed for these applications, along with extra information, are available for download from the Elektor Electronics website.Before we present the individual example applications, a few initial remarks are in order regarding the example programs and their use.– The applications and demonstration programs are written in C51 code in such a way that (with one exception) they can be used with the restricted version of µVision2 (maximum code size of 2 Kbytes, no floating-point arithmetic). For larger application programs the full version of µVision2, or another 8051 tool, must be resorted to.