used so that costs can be optimally prorated. Figure 27 compares the costs of the two schemes for implementing control, as a function of the number of control steps. This assumes an average cost of 0.6 per hardwired control step and an average of one 8-bit word in the memory for a software control step. The remarks of the earlier part of the section come into clear view here. With few control steps (less than about 80) the fixed costs of K(PCS) make it more costly; above this point the software scheme gets progressively more advantageous. The steps in the cost function of K(PCS) are caused by having to obtain control memory in discrete blocks of 256 words each.
Fig. 27. Graph of cost of control part versus control steps for hardwired and K(PCS) cases.