Even in 1993, Charles still used only a plug-in calculator circa 1970, with blue keys the size of dimes, very rugged keys, which was indeed fortunate given the pounding he would give it when reproducing calculations by hand that some state-of-the-art mainframe, the pride of IBM and the size of a refrigerator, had no doubt taken many minutes to complete in some sealed room.
FORBES: What Makes a Good Founder? Hint: It's in the details