sentences: The purposes of this paper are to review the microinstruction sequencing capabilities of several microprogrammed computers; to determine whether these sequencing capabilities permit easy implementation of the control constructs of flowchartable program logic in modular microcode; and to present a set of microinstruction sequencing functions which will support "structured" microprogramming. Several microprogrammable mini- and microcomputers which provide the user with the means for implementing special purpose instruction sets have been introduced relatively recently. However, the experiments by Weber and Balzer which demonstrated the possibilities for increasing computation speeds, decreasing main memory space usage, and easing the task of applications programming by means of special purpose instruction sets implemented in microcode were performed some time ago.