The control store and microsequencer provides the means of controls of the operation of the other functional units with microcode. The control store has a ROM containing 1,600 41-bit words. Each 41-bit word is divided into two, a 28-bit field that controls the functional units, and a 13-bit field that controls the microsequencer. Unlike the MicroVAX 78032, which uses X-shaped cells, the 78034 uses conventional H-shaped cells. The microsequencer's purpose is to supply microaddresses to the control store.