The Dream Machine: J. C. R. Licklider and the Revolution That Made Computing Personal

by M. Mitchell Waldrop

Since the users would be sharing the computer's processing time as well as its storage space, McCarthy took to calling his scheme time-sharing. And characteristically, he wasn't too impressed with himself for having thought it up. "Time-sharing to me was one of these ideas that seemed quite inevitable," he says. "When I was first learning about computers, I [thought] that even if [time-sharing] wasn't the way it was already done, surely it must be what everybody had in mind to do." Wrong. Nobody at IBM had even imagined such a thing, not in 1955. It's true that the company was the prime contractor for the SAGE air-defense system, which called for "time-sharing" in the sense that one central computer would control many radar terminals. But the SAGE computer would be running just one overall program to manage everything, with the individual radar operators' being limited to a few standard queries and responses. McCarthy's proposal was far more radical. He wanted to give the users free rein inside the computer so they could play, experiment, meditate, run programs, modify programs, crash programs, and waste time as they pleased. In effect, he was proposing to optimize human time instead of machine time. But in 1955, at IBM, that kind of proposal sounded both naive and self-indulgent. For one thing, the technology wasn't up to it. The computer memory that McCarthy was so blithely planning to carve up was in fact very expensive and very small (core memory was just making its co...