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Thanks For the Memories: Touring the Awesome Random Access of Old (hackaday.com)
szczys writes: The RAM we use today is truly amazing in all respects: performance, reliability, price; all have been optimized to the point you can consider memory a solved problem. Equally fascinating is the meandering path that we've taken over the last half century to get here. Drums, tubes, mercury delay lines, dekatrons, and core memory. They're still as interesting as the day electrons first ran through their circuits. Perhaps most amazing is the cost and complexity, both of which make you wonder how they ever manage to be used in production machines. But here's the clincher: despite being difficult and costly to manufacture, they were all very reliable.
At the very least in the next few years the form factors will change from DIMMs to perhaps HBM stacked on-die and fiberoptic DIMMs.
We don't need fiberoptic links for memory because it is not inconvenient to provide a very broad path between the CPU and the RAM. They would provide literally no benefit.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Yes and no, if you are thinking about your computer or single server sitting beside you. If you are thinking of next gen data centers and virtualized servers, being able to supply a bus to RAM over a fiber link is very interesting. Think of a server component or appliance you install into a rack, then fiber link to your Hosts to supply more ram. There is a limit to the amount of ram slots on a server, a physical limit. Fiber links would open up the ability to have external ram that doesn't actually need a slot. Fiberlinks take considerably less space. And if this was an option, I suspect you'd have a fiber trunk coming from the host. This could actually be genius.
Saying that a problem is solved is risky. Remember that the physics was solved shortly before Einstein et all! The future might reshape our perception, with for instance RAM and ROM convergence: https://en.wikipedia.org/wiki/...
Optical interconnection is very efficient and good fidelity and low interference, but ease of manufacturing complex interconnection and creating multiple permanent connections is still lacking, compared to electric/metal. In addition to that, drivers/receivers are bulky and dissipate too much power. Before photonics can replace electronics, there'll have to be a revolution in miniaturisation and low power for fiber drivers/receivers, as well as analogue mass production technological processes to board etching and component soldering of today.
One thing we have forgotten about is the impact (literally) of cosmic rays on memory cells. The old core planes were not very sensitive to the effect of an alpha particle from space zipping through the little donuts and changing values. But solid state RAM certainly was. In the old days, funny things would occasionally happen as a result of cells having their stored values flipped from 0 to 1 or back. These were rare random events that became more frequent as the amount of memory and its density grew. High reliability machines like servers used error correcting memory (ECC) that added a few extra bits so a change could be detected when the cell was read and hopefully recovered. The source of the problem is still there.. and so is ECC memory.
On the other hand the relationship between a system's reliability and the reliability of the system's components isn't one-to-one. You can build unreliable systems out of reliable components, and more surprisingly, you can build reliable systems out of unreliable components. That latter principle is the basis for the Internet, which provides end-to-end communication that is more reliable than any of the possible paths between those endpoints.
Every component is unreliable to some degree; as it becomes increasingly reliable it moves from unusable, to something you can work around, to something whose potential failure you can ignore in many applications.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
Apparently back in the day, core memory actually was a bit difficult to manufacture. Back in the 1960s, they wired the cores by hand and that apparently required quite a bit of manual dexterity. The first digital computer I ever saw was SWAC at UCLA (https://en.wikipedia.org/wiki/SWAC_(computer)). 256 37 bit words of Cathode Ray Tube memory. I have no real idea how it worked, but I recall that on days when it chose to work, there were a bunch of CRTs displaying an 8x8 matrix of zeros and ones. The professor in charge of the thing told us in his rather thick European accent that they were trying to augment the CRT memory with core, but that so far his graduate student(s) hadn't been able to thread the core wires well enough.
You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
Yep, I can verify that. Worked for Data General and the original Nova series used all core memory. The "core stacks" arrived in Mass from Asia and were then mounted on the memory card itself. Took the cover off of a dead one one time and it looked like velcro until I got it under a magnifying lamp. Even then, I was amazed at the dexterity it must take!