A powerful computer fills a room
The core idea stands, but key numbers or details have changed.
TaughtSerious computing power means a mainframe: a machine the size of a room, run by specialists, that you submit jobs to. Personal computers are for word processing and games.
NowThe phone in your pocket is a supercomputer by the standards of most of the twentieth century. A modern smartphone outperforms the Cray-2, the fastest machine on Earth in 1985, by orders of magnitude, and the iPhone's 2007 launch made that the default condition of ordinary life.
What actually happened
The Cray-2 in 1985 hit about 1.9 gigaflops, cost around 17 million dollars, filled a room, and had to be immersed in liquid coolant. It was the most powerful computer in the world. A current flagship phone reaches multiple teraflops on its GPU, meaning something like a thousand times faster, in a device that costs a few hundred dollars, weighs 200 grams, and runs on a battery.
The usual comparison, that a phone has more computing power than the Apollo Guidance Computer, dramatically undersells it. The AGC ran at about 0.043 MHz with 4 KB of RAM. A phone beats it by a factor in the hundreds of millions, which is such an absurd ratio that it stops being informative.
What the room-sized machine actually became is the data center, which is genuinely the size of a building and which your phone talks to constantly. So mainframe-scale computing did not vanish, it moved somewhere you cannot see and rented itself out by the second. But the classroom framing, that real computing is institutional and remote while your own machine is a toy, inverted completely.
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Sources
- Computer History Museum: Timeline of Computer Historycomputerhistory.org
- NASA: The Apollo Guidance Computernasa.gov
Who was taught this
Still standard through 2000, so anyone who finished school between 1950 and 2007 learned the earlier version.