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Because of the medical examination, this additional class of employee would need to be considered rather carefully in any change of the group insurance plan.

AN APPRAISAL OF THE CALCULATOR

In appraising the Kalin-Burkhart Logical-Truth Calculator, we must remember that this is a first model. It was the only machine of its kind up to the end of 1948; and it worked.

The cost of the machine, as stated before, was about $150 of parts and perhaps $1000 of labor. This is less than ¹/₁₀₀ of the cost of the other giant brains described in previous chapters. Yet we can properly call this machine a mechanical brain because it transfers information automatically from one part to another of the machine, has automatic control over the sequence of operations, and does certain kinds of reasoning.

The machine is swift. It can check up to a 100 cases against a set of rules in less than 1 minute. It can check: 128 cases for 7 conditions in 1¼ minutes, 256 cases for 8 conditions in 2½ minutes, and 4096 cases for 12 conditions in 38 minutes. That is the limit of the present machine. Of course, setting up the machine to do a problem takes some more time.

The programming of this machine to do a problem is less complicated than the programming of most of the big machines previously described. Of course, in order to prepare a problem for the machine, the preparer needs to know a fair amount of the algebra of logic. This, however, is not very hard. As to reliability, the machine has in practice been out of order less than 2 per cent of operating time.

The big barrier to wide use of the machine, of course, is lack of understanding of the field of problems in which it can be applied. Even in this modern world of ours, we are in rather a primitive stage in regard to recognizing problems in logical truth and knowing how to calculate it. Here, however, is an electrical instrument for logical reasoning, and it seems likely that its applications will multiply.

Chapter 10
AN EXCURSION:
THE FUTURE DESIGN OF MACHINES THAT THINK