Computers and calculators were too slow and cumbersome for pit trading

Evidence

In the 1970s and for most of the 1980s, it would have been against the rules of the Chicago Board Options Exchange to use a computer on the trading floor, and to my knowledge no one tried: the computers of the period were too cumbersome. … Most traders seem to have regarded calculators as too slow for use in a pit. Even the few seconds it would take to input parameter values and wait for a solution could mean a loss of profitable trading opportunities. Furthermore, making the necessary adjustment to take into account the payment of dividends was “difficult and time-consuming.” In consequence, few “use [programmable calculators] regularly for option evaluation after the initial novelty wears off” (Gastineau 1979, pp. — Donald MacKenzie, An Engine, Not a Camera, 714