Word: backtracked
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Dates: during 1970-1979
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Unbelievably Successful. The system still has its own gaps. For example, a motorist who refuses or is unable to follow the pacer lights can frustrate the computer, which tries frantically to backtrack and pick up his car again. A second phase of the testing will involve a less complex arrangement of moving bands of green and white light on an electronic railing along the ramp; a driver who cannot or will not keep abreast of a green band (programmed, like the pacer lights, to deliver him to a predetermined slot in highway traffic) can either fall back and pick...
...only 77 steps long. But those 77 steps made the building process immensely complex. Adding one lab-made nucleotide at a time in complex chemical processes, Khorana's team patiently assembled small, single-stranded segments of the 77-step chain. After each step forward, the scientists had to backtrack: every new combination had to be unraveled in order to check that the nucleotides were still in the right sequence and had not been damaged by chemical side effects. When enough strands had been produced to make complementary pairs, Khorana lined them alongside each other to form segments...