Dynamic and user microprogramming are usually used to refer to the same concept. In this paper, we will make a clear distinction between the two terms. User microprogramming was used by military applications for optimization purposes. But, in commercial applications its importance was not realized, because microprogramming was treated as a transparent item to the user. This paper will prove the feasibility of user microprogramming in commercial applications and how it can be used to build cost effective optimized control units. We will also show the feasibility of building a combined micro/macro instruction set. To allow this we will give a modified definition of microprogramming.