Comment by syndicatedjelly | Hacker News Reader

Comment by syndicatedjelly | Hacker News Reader

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syndicatedjelly

The 1950s were a time in computing where it wasn't a given that digital computing was clearly "better". We still hadn't developed methods of mass-producing reliable, fast, and cheap microelectronics and controllers. So for high-reliability applications, analog computing was THE solution.

In 1954, Rex Rice wrote this piece about preferring a simple plugboard as the means of programming a computer, versus any sort of abstraction with a programming language (https://dl.acm.org/doi/10.1145/1455270.1455272). So it was still very much up for debate, whether high-level programming languages were even the right solution for the problems being faced.

But I agree with you, our forefathers were simply geniuses to have figured out how to manipulate the physical world to produce mathematical computations. Early in his career, my dad had to disassemble and reverse-engineer some Soviet-made aerospace devices, and he still fondly recalls how superbly engineered and precise the Soviet devices were. I wish there was more information out there about Soviet computing, but the winners do write history after all.

My understanding the surprising factor that settled the debate for analog vs digital computers. was that digital computers require far less precise electronics. the voltage in an analog computer has to be exactly 5.2648 volts, every resister, capacitor, transistor has to be a high precision part, the more complex the computer the higher precision required. while in a digital computer "close to 5 volts" is good enough. this makes the components cheaper, more reliable and smaller. and as such the digital computer won.

This is why I have my doubts about existing designs for quantum computers, the quantum algorithms we are trying to solve in hardware require an analog design and we rejected analog computers before, mainly because they were unable to scale. This inability to scale is the same problem we see with quantum computers.

Not only is "close to 5V" "good enough", it's so "good enough" that we consider a CPU running a program practically idealized. When programming a computer, you largely don't think about any hardware cases going wrong, because they're so vanishingly rare.

This is a huge departure from the physical world, and it speaks to what a massive benefit computers bring.

The best part of a computer is its utter disconnection from reality.

I wonder if EMP resistance was also considered, and if analogue computing could have offered better resistance compared to the digital devices of the time.

Impossible to know, though the use of nuclear weapons by an enemy was probably on everyone's mind, and diversity of redundant systems may have been applied in case some hypothetical enemy air defense came about during the lifespan of the aircraft.

Probably not a factor. There is a backup attitude indicator on the bottom right side of the panel. So a more modern version would have gone digital for the PFD (more options for extra indications) even with EMP risks considered and just kept the analog backup instrument.

It's interesting that you note the unreliability. I always assumed tubes were unreliable, but thought anything solid state (even those card based systems) would be "reliable enough" to start taking for granted.

But then you look at it and think Yeah, obviously they're not going to have MTBF times in the millions. It's going to be hundreds of hours - once a week, or maybe every few weeks between real hard crashes.

How would that change your behaviour.

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