Dorothy Vaughan was keenly aware of that undulating invisible line that separated the past from the future. At fifty years old and many years into her second career, she reinvented herself as a computer programmer. Engineers still made the pilgrimage to her desk, asking for her help with their computing. Now, instead of assigning the task to one of her girls, Dorothy made a date with the IBM 704 computer that occupied the better part of an entire room in the basement of Building 1268, the room cooled to polar temperatures to keep the machine’s vacuum tubes from overheating.
