Geoffrey Swenson apparently, her code was put on punch cards to be simulated, then hard wired by hand, theaded onto copper rings, and inserted into the computer.
Once the code was solid, it would be shipped off to a nearby Raytheon facility where a group of women, expert seamstresses known to the Apollo program as the “Little Old Ladies,” threaded copper wires through magnetic rings (a wire going through a core was a 1; a wire going around the core was a 0). Forget about RAM or disk drives; on Apollo, memory was literally hardwired and very nearly indestructible.
Matt Corby That’s core memory, which is RAM. (Well, more like Flash memory, in practice.) In those days, ROM was typically a diode array with cuttable links. It’s unlikely that the code was hard-wired into the machines, though.
There was something awesome about the smell of the line printers I dealt with. But it was the punched cards that were awful, especially if you dropped them.
Regular core is rewritable (in fact, it has to be rewritten after each read, because the read destroys the information), but the knotted stuff could not be changed at all. And had to be delivered long before the rest of the hardware was finished. (As a wee lad I edited an article of hers, and she was delightful.)
John Hardy Developer 
Back when you had to print your code on a big line printer. I wonder if she had to use punch cards to write it?
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Given the era, I would say so.
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Geoffrey Swenson apparently, her code was put on punch cards to be simulated, then hard wired by hand, theaded onto copper rings, and inserted into the computer.
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Once the code was solid, it would be shipped off to a nearby Raytheon facility where a group of women, expert seamstresses known to the Apollo program as the “Little Old Ladies,” threaded copper wires through magnetic rings (a wire going through a core was a 1; a wire going around the core was a 0). Forget about RAM or disk drives; on Apollo, memory was literally hardwired and very nearly indestructible.
http://www.wired.com/2015/10/margaret-hamilton-nasa-apollo/
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W.O.W!
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Core memory, oh yeah! Thus where the term came from that is used today. Little donuts with wire. Awesome stuff!
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Matt Corby That’s core memory, which is RAM. (Well, more like Flash memory, in practice.) In those days, ROM was typically a diode array with cuttable links. It’s unlikely that the code was hard-wired into the machines, though.
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When they got done with core memory they had people using microscopes wiring it up, shockingly expensive.
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‘When I first got into it, nobody knew what it was that we were doing. It was like the Wild West.’ — Margaret Hamilton
Well, some things haven’t changed.
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So I guess that is all assembler code? Or maybe the 1960s equivalent of VHDL or Verilog?
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Ramin Honary Assembler.
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There was something awesome about the smell of the line printers I dealt with. But it was the punched cards that were awful, especially if you dropped them.
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Regular core is rewritable (in fact, it has to be rewritten after each read, because the read destroys the information), but the knotted stuff could not be changed at all. And had to be delivered long before the rest of the hardware was finished. (As a wee lad I edited an article of hers, and she was delightful.)
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