LOL Memory

Thursday, July 16th, 2009

The Apollo navigation computer needed to be small and reliable, and it couldn’t use much power, so it was built with some of the first integrated circuits — and something called LOL memory:

In order to make sure that the software was robust it was “woven” into so-called “rope core memories”.

These used copper wires threaded through or around tiny magnetic cores to produce the ones and zeroes of binary code at the heart of the software.

Pass the copper wire through the core and the computer read it as a one. Pass it around and it was read as a zero.

“Once you get it wired it’s not going to change without breaking those wires,” said Mr Hall.

The rope core memories would become know as “LOL memory” after the “little old ladies” who knitted together the software at a factory just outside Boston.

These ladies would sit in pairs with a memory unit between them, threading metres and metres of slender copper wires through and around the cores.

“It’s an extremely time-consuming process and it meant that the programs had to be finished and fully tested months in advance,” said Mr Eyles.

“But it is extremely robust – that information probably still exists despite being left on the Moon.”

To ensure reliability and the highest possible standards from the ladies, Nasa also chose to go on a PR mission to the factories.

“We used to go to the cafeteria and the astronauts would come in,” said Mary Lou Rogers, one of the ladies who worked on the Apollo line.

“They’d explain the Moon shot and thank us for what a good job we were doing.

“Everybody got all excited when they came in — we were a bunch of married women with children.”

However, Nasa did not just leave quality control to good will and chance, said Mrs Rogers, who also worked on Intercontinental Ballistic Missile programmes.

“[Each component] had to be looked at by three of four people before it was stamped off. We had a group of inspectors come in for the Federal Government to check our work all the time.”
“It was bad when we worked on Poseidon and Trident. But nothing as bad as when we were on Apollo.”

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