He meant exactly what he said.
For example.. The memory used in the Apollo onboard computers used core store. This consisted of tiny ferrite beads threaded onto a matrix of wires. One bit of data was stored in each ferrite bead.
In computing , magnetic-core memory is a form of random-access memory . It predominated for roughly 20 years between 1955 and 1975, and is often just called core memory , or, informally, core . A 32 × 32 core memory plane storing 1024 bits (or 128 bytes ) of data.
The small black rings at the intersections of the grid wires, organised in four squares, are the ferrite cores. Core memory uses toroids (rings) of a hard magnetic material (usually a semi-hard ferrite ). Each core stores one bit of information.
Two or more wires pass through each core, forming an X-Y array of cores. When an electrical current above a certain threshold is applied to the wires, the core will become magnetized. The core to be assigned a value – or written – is selected by powering one X and one Y wire to half of the required current, such that only the single core at the intersection is written.
Depending on the direction of the currents, the core will pick up a clockwise or counterclockwise magnetic field, storing a 1 or 0. This writing process also causes electricity to be induced into nearby wires. If the new pulse being applied in the X-Y wires is the same as the last applied to that core, the existing field will do nothing, and no induction will result.
If the new pulse is in the opposite direction, a pulse will be generated. This is normally picked up in a separate “sense” wire, allowing the system to know whether that core held a 1 or 0. As this readout process requires the core to be written, this process is known as destructive readout , and requires additional circuitry to reset the core to its original value if the process flipped it.
When not being read or written, the cores maintain the last value they had, even if the power is turned off. Therefore, they are a type of non-volatile memory.
Depending on how it was wired, core memory could be exceptionally reliable. Read-only core rope memory , for example, was used on the mission-critical Apollo Guidance Computer essential to NASA ‘s successful Moon landings.
Using smaller cores and wires, the memory density of core slowly increased. By the late 1960s a density of about 32 kilobits per cubic foot (about 0.9 kilobits per litre) [ citation needed ] was typical. The cost declined over this period from about $1 per bit to about 1 cent per bit.
Reaching this density requires extremely careful manufacturing, which was almost always carried out by hand in spite of repeated major efforts to automate the process. Core was almost universal until the introduction of the first semiconductor memory chips in the late 1960s, and especially dynamic random-access memory (DRAM) in the early 1970s.
Initially around the same price as core, DRAM was smaller and simpler to use. Core was driven from the market gradually between 1973 and 1978. Although core memory is obsolete, computer memory is still sometimes called “core” even though it is made of semiconductors, particularly by people who had worked with machines.
Core store memory hasn’t been made since the mid 1970s. The factories and tooling at made core store have long since been destroyed. We could rebuild the factories, train up staff and make some more but it makes no sense at all to do so.
The memory board above stores just 128 bytes of data. Below is a picture of a modern Micro SD card sitting on some core store. The core store in the background stores just 8 bytes. The SD card stores 8,000,000,000 bytes.
If you were building a new spacecraft you wouldn’t copy one of the Apollo spacecraft as that would require rebuilding the factories that made the core store and hundreds other technologies that no longer exist. It makes much more sense to design a new one that uses modern available technology.
Below are a photo of the of the Saturn V Instrumentation Ring and a diagram annotating what you are looking at.
What I want to point out are the computers, how large they are and how much they must weigh.
Modern mobile phones each have more computing power than existed on Earth at the time that these things were built.
I saw one of these in person at the Marshall Space Flight Center Museum in 1985. I was amazed by how much progress in size and computing power we’d made at that time. And at that time an IBM PC-XT was new and had more computing power and memory than the computer in the Instrumentation Ring.
Notice the man sitting at the desk on the left side of the Instrumentation Ring for a size reference.
So, why would you want to use this generation of computer even if it was available, when you could buy something that was less than 1% of the weight and power consumption and over 1,000 times the computing power and storage?
