A class of signal-based identification-free auto-tuners, simple algorithmically provided and implemented on portable single-board microcomputers is found to be well suited to control a wide range of industrial processes met in practice, which are uncertain in the sense that it is not possible to determine what the future output of the process precisely will be.The implementation of a class of auto-tuning controllers using portable single-board microcomputers is described. The class is found to be well suited to solving a range of industrial control problems through a well-known PID-based control. The ubiquitous PID algorithm was chosen because of its familiarity, timeproven utility, and applicability to the majority of industrial feedback control problems and its operations are intuitively understood by most process engineers. Adaption loops work like an ordinary control loop. For evaluating them no special test disturbances are necessary, the current control process being quite sufficient for the auto-tuning. Hardware and software details of portable single-board microcomputers, SCX-48, SCX.51, and SCX-80, respectively are presented with particular reference to the use of the new auto-tuning algorithms. The hardware has been designed with MCS 48, MCS 51, MCS 80, MCS 88 sets of components and is equipped with a serial port to connect to certain personal computer through an RS 232/CCITT V.24 voltage levels. These controllers were succesfully tested on simulated and real industrial plants.