Another key design decision is the allocation of control information between registers and memory. It is common to dedicate the first (lowest) few hundred or thousand words of memory for control purposes. The designer must decide how much control information should be in registers and how much in memory. The usual trade-off of cost versus speed arises.Another key design decision is the allocation of control information between registers and memory. It is common to dedicate the first (lowest) few hundred or thousand words of memory for control purposes. The designer must decide how much control information should be in registers and how much in memory. The usual trade-off of cost versus speed arises.