E. BREAKDOWN OF COSTS BY SYSTEMS
In Figure 14 the cost of the standard I/O equipment is shown plotted against the cost of the CPU for 36 different systems. The high point labeled "T" represents a system having many high-speed magnetic tape drives. The low point labeled "R" represents the Rochester system, which must be considered unbalanced, because its only "standard" I/O equipment is four Dectapes, which should, perhaps, have been defined as CPU items, since they cannot be used for communication with most computing centers. If a line printer and two IBM-compatible tape units were added, the Rochester point would have to be raised at least as high as the position R'. The straight line shown in Figure 14 was drawn with a slope of one half. It may perhaps be taken to represent a rough statistical reflection of the collective experience accumulated over the past six years or so regarding the relative costs of I/O and CPU equipment. In Figure 15 DAS costs are plotted against CPU costs for the same 36 systems. Here the spread of the points is worse than in the previous case, as expected for the reasons mentioned earlier. The exceptionally high point labeled "PHA" represents a system with three large pulse-height analyzers, two of them 20,000-channel units, in the DAS. The straight line shown has the equation y = 8.0 + 0.7x. The overall DAS cost is 77 percent of the total CPU cost.