That's One Small Computer For Man

One Giant Leap For Minimal Processing Power

I received a group email a couple of days ago, telling me that the computers on Apollo XI had about 60 KB (yes, kilobytes) of memory. So I did some scouting around and found this great article at abc.net.au. In a nutshell, this is what it says. The computer had to control a 13,000 kg spaceship, orbiting at 3500 km/h, land within metres of a specified location and guide it back from the surface to rendezvous with the Command Module in lunar orbit. There was no margin for error, as the Lunar Module, carrying Neil Armstrong and Edwin Aldrin, carried only enough fuel for one landing attempt. So, what were the specs of the vital computer? It weighed 30kg. It didn't have a disk drive, only 74 kilobytes of memory that had been literally hard-wired, and all of 4 KB of something akin to RAM, or random access memory. In order to use the computer, astronauts used a display and keyboard unit (DSKY, pronounced "disky" - see image above right), which weighed another 10kg. It was not a QWERTY keyboard, but a number pad along with some special buttons. In order to input a command or action, the user had to press a button marked "Verb", followed by a number that corresponded to the action. To input data, the user pressed the "Noun" button along with a number. But, as we all know, the MIT-developed system worked perfectly. If you want to read more about the error message that almost caused a crisis at Mission Control as Eagle descended towards the lunar surface, use the link above. It's gripping stuff - and it's history we didn't know.