This paper addresses the problem of compacting microcode for complex systolic systems used as accelerators for traditional computers. For this sort of system, the purpose is to have a low-level programming paradigm that is simple enough for those users that are not completely aware of hardware details. The microcode should be issued from a high-level language application developed on the host processor. The paper introduces an effective technique to structure the microcode into elementary primitives and a simple compaction algorithm to shorten the microcode program. This compaction strategy has been tested on a real machine to implement a neural-network algorithm and some results are reported.