Abstract: Propose a kind of d. c. servo systems in which a MC68000 microcomputer is used as the controller, a tachometer generator as an element of the speed feedback and a 14-bit light-electricity coder as an element of measuring angular position, Basing on the model-reference adaptive control theory, we design the speed loop in order-to compensate the effect of the dry friction and the change of the iriertia on the dynamic performances of the system, In designing the position loop, furthermore, we transform the model of the system into a linear one so that we obtained a linear optimal controller. The results of the operation of this system are satisfactory.