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Apollo 11 Guidance Computer vs. USB-C Chargers

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Re: Apollo 11 Guidance Computer vs. USB-C Chargers

#71

Post by ghaff »

segfaultbuserr wrote: post #62
ghaff wrote: post #31

Earlier quoted context omitted.

>No one understands how the engines on the Saturn V work anymore. That's not really true [1]. Although the project is dead AFAIK a fair bit of work went into reviving the F-1 engine in the early 2010s. >And the guidance systems would have to be built back up from scratch. As with many things, you can't easily replicate complex old artifacts because you don't even have the tools to make the tools to make the tools...…

> I doubt you could easily get things like rope core memory or just about any of the components. " Any of the components" is an exaggeration. For example, bipolar transistors are still here, here's the schematics [0] of the switched-mode power supply in the AGC - still perfectly understandable, rebuilding it can a fun weekend project. Also, discrete NOR gates are still around, although the underlying technology is di…

Fair enough.

>whether the Saturn V architecture has survived

We understand very well the basic approach that was taken to land on the moon and the hardware we used to do so. We'd have to re-engineer a lot of things that aren't just off-the-shelf to do it again. But we could do so pretty quickly if there were any compelling reason to do so.

As I understand it, current technologies that could include moon landing are being worked on in the broader context of going to Mars.

Re: Apollo 11 Guidance Computer vs. USB-C Chargers

#74

Post by dfox »

dave_blob wrote: post #58
gok wrote: post #22

Yeah modern microcontrollers are probably less efficiently used than they could be, but the AGC essentially crashed twice during the lunar landing because it didn't have enough compute available.

The real fun with the AGC on landing happened on Apollo 14, with a flipped bit in the abort landing flag. Percussive maintenance temporarily flipped the bit back, giving enough time for ground control to develop a hack. Didn't they just ignore the warnings on Apollo 11? And I think it was non synced timing references rather than strictly resource availability that got them on 11

The reason for warnings on 11 was that the landing was done in what was essentially an unsupported configuration. Still the “kernel” behaved as designed, didn't run low priority task (that was not supposed to be running in the first place) and raised an warning about doing so.

Re: Apollo 11 Guidance Computer vs. USB-C Chargers

#75

Post by op00to »

xkemp wrote: post #36
jedberg wrote: post #12

And despite the fact that a wall charger has more compute power than the Saturn V, we can't actually go to the moon today. We've actually lost the ability to go. No one understands how the engines on the Saturn V work anymore. It would take years to tear them apart and analyze them, and most of the original engineers are dead. And the guidance systems would have to be built back up from scratch. Kind of sad if you th…

We could easily go to the moon. It's just a completely useless exercise to do so, unless you can find a way to taunt China into another round of the space race. The scientific case for the moon was always weak, and most anything they could come up with has been done. Just look at the useless lets-grow-salad-in-space-oh-look-its-just-salad timesinks the ISS has been busying themselves with. So, in a way we've become m…

> useless lets-grow-salad-in-space-oh-look-its-just-salad timesinks

This is called basic research. It's geared towards building greater knowledge of a study area without specific concerns towards application. That's how science works. We don't just fund the stuff that's immediately profitable (though things are shifting that way).

Re: Apollo 11 Guidance Computer vs. USB-C Chargers

#76

Post by jvm_ »

dave_blob wrote: post #58
gok wrote: post #22

Yeah modern microcontrollers are probably less efficiently used than they could be, but the AGC essentially crashed twice during the lunar landing because it didn't have enough compute available.

The real fun with the AGC on landing happened on Apollo 14, with a flipped bit in the abort landing flag. Percussive maintenance temporarily flipped the bit back, giving enough time for ground control to develop a hack. Didn't they just ignore the warnings on Apollo 11? And I think it was non synced timing references rather than strictly resource availability that got them on 11

The docking (like find your way back to the mothership radar) was still turned on, so the CPU was receiving the data and having to process it.

The CPU was throwing an I'm overloaded signal, but dealing with it, as the process priority put docking radar as less priority than the landing sequence.

So the CPU was complaining but still doing it's job.

All this is from memory :P

Re: Apollo 11 Guidance Computer vs. USB-C Chargers

#77

Post by wwweston »

vardump wrote: post #59
TazeTSchnitzel wrote: post #29

Earlier quoted context omitted.

If it can be done efficiently in asm then it can be done in C, C++, perhaps even Rust. But there are sacrifices to be made: unmaintainable “clever” code without clean abstractions.

There are architectures that are just fundamentally C-hostile. Perhaps the most famous one is 6502. No efficient way to implement stack based parameter passing, generic pointer arithmetic, and lots of other bits and pieces. You can still use C on 6502, it's just not very fast. I guess you could define another language that mostly looks like C, but built around particular CPU architecture quirks.

What are some languages (other than its own instructions) that 6502 is friendly to?

Re: Apollo 11 Guidance Computer vs. USB-C Chargers

#78

Post by grawprog »

flatiron wrote: post #64
J5892 wrote: post #60

Earlier quoted context omitted.

- How many Apollo 11 guidance computers would you need to run Doom?

I believe you require a 32 bit computer and I think those were 15. So no doom :(

Though, where there's a will there's a way...

https://doom.fandom.com/wiki/16-bit

>After the release of Doom II on the PC, the original three episodes were released to some 16-bit consoles that used special 32-bit enhancement hardware. For the Sega Genesis, the 32X allowed for additional address space to enable Doom to run its demanding resources of the time which a 16-bit system wouldn't have handled. Whereas with the SNES, the Super FX 2 chip inside the DOOM cartridge allowed for an internal co-processor of the game cartridge to eliminate the need for bulky addons for the aging SNES.

Would it count if you somehow built in a 32-bit coprocessor for your 15-bit apollo doom port?

Re: Apollo 11 Guidance Computer vs. USB-C Chargers

#79

Post by nostrademons »

crmrc114 wrote: post #3

This is awesome! The media loves to say your pocketwatch is more powerful than X form $date. This is a fun technical rundown. I think at some point we have to start talking about how far from optimized we are https://en.wikipedia.org/wiki/MenuetOS comes to mind when talking about what can be done in fasm. Are we ever going to get compilers to the point where we can squash things down to that size and efficiency? Is t…

> Are we ever going to get compilers to the point where we can squash things down to that size and efficiency?

Compilers are already that good.

The problem is economics. If you have an OS that uses up 1% of the available CPU budget, there will be pressure from management & product to spend the additional 99% on additional bells & whistles. Maybe you add fancy animations and transitions to window opening. Maybe you add full-HD search and spend additional CPU cycles indexing. Maybe you add transparent cloud storage and spend the additional CPU cycles backing up files. Maybe you add new frameworks for developer productivity, all of which suck up CPU time.

And the thing is - from a business perspective, these are all the right thing to do. Because having a slick, glossy UI and a long list of useful features will sell more copies, while being able to run it on a USB-C charger or 25 year old computer will probably not sell more copies.

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