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Apollo 11 vs. USB-C Chargers (2020)

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Re: Apollo 11 vs. USB-C Chargers (2020)

#181

Post by Anarch157a »

KMag wrote: post #76
Tommstein wrote: post #61

Earlier quoted context omitted.

Presumably they meant a program being discovered to be wrong before the computer was actually launched. And meant literally building a whole new computer, not just recompiling a program.

For the Apollo Guidance Computer, changing the program meant manually re-weaving wires through or around tiny magnet rings. A good part of the cost of the computer was the time spent painstakingly weaving the wires to store the program.

Only if the bug was caught after the computer had been assembled for the mission. For development, they used a simulator. Basically, a cable connected to a mainframe, with the bigger computer simulating the signals a bundle of core rope would produce.

Re: Apollo 11 vs. USB-C Chargers (2020)

#182

Post by garaetjjte »

denton-scratch wrote: post #168
KMag wrote: post #76

Earlier quoted context omitted.

For the Apollo Guidance Computer, changing the program meant manually re-weaving wires through or around tiny magnet rings. A good part of the cost of the computer was the time spent painstakingly weaving the wires to store the program.

Pardon me, but why would you have to re-weave wires around magnetic rings? The magnetic rings are for storing data; the whole point is that you can change the data without rewiring the memory. If you have to re-wire permanent storage (e.g. program storage), that's equivalent to creating a mask ROM, which is basically just two funny-shaped sheets of conductor. There's no need for magnetic rings.

https://www.youtube.com/watch?v=hckwxq8rnr0

Re: Apollo 11 vs. USB-C Chargers (2020)

#183

Post by simne »

> The CYPD4225 is definitely not rated for space.. if it would work in space

It will. Not too long and not very reliable, but will.

From history of space rockets, they was definitely first created as "two purpose" (except, may Vanguard, which was totally civilian program), so their electronics considered possible radiation from nuclear war, but fortunately, in space found natural radiation, but slightly other type (spectrum). Currently, SpaceX just use industrial grade computers on rockets (not RAD hardened).

Well, look at tech details: for RAD digital electronics exists two types of problems.

1. Random spikes (switches) from high energy charged particles. Unfortunately, only Military RAD grade parts have integrated safety mechanisms, for Civ/Industry grades, could make shield with EM field and thick layer of protecting material, like Lead or even Uranium. When thyristor effect happen, need to power circle (turn off/on and boot), and this is risks source for mission, but most probably, it will withstand flight to Moon.

2. Aging of semiconductor structure from constant flow of particles with high penetration - basically it is just high speed diffusion, which destroy semiconductor structures. But for Earth-Moon environment, this is issue for long term operations (months or even years).

So, will work.

Re: Apollo 11 vs. USB-C Chargers (2020)

#184

Post by denton-scratch »

KMag wrote: post #175
denton-scratch wrote: post #168

Earlier quoted context omitted.

Pardon me, but why would you have to re-weave wires around magnetic rings? The magnetic rings are for storing data; the whole point is that you can change the data without rewiring the memory. If you have to re-wire permanent storage (e.g. program storage), that's equivalent to creating a mask ROM, which is basically just two funny-shaped sheets of conductor. There's no need for magnetic rings.

No, I'm not talking about magnetic core memory. Core rope memory also used little magnetic rings. https://en.wikipedia.org/wiki/Core_rope_memory input wires were energized, and they were coupled (or not) to the output wires depending on if they shared a magnetic ring (or not).

Thanks! I'd never heard of rope memory.

Re: Apollo 11 vs. USB-C Chargers (2020)

#185

Post by xcv123 »

ianburrell wrote: post #177
codezero wrote: post #83

Earlier quoted context omitted.

I expect nation state actors to have immensely more access to computing power than the commercial sector, is that controversial?

If you look at the top supercomputers, US national labs occupy most of the top 10. But they aren’t enormously larger than the others. They are also built of out of standard parts. I’m surprised that they are recent, I expected the government to be slow and behind. What do you expect US government to do with lots of computing power? I wouldn’t expect military to need supercomputers. Maybe the NSA would have a lot for…

> They are also built of out of standard parts. I’m surprised that they are recent, I expected the government to be slow and behind.

Because the government isn't building them. They are Cray supercomputers, supplied by HPE. Not entirely built with standard parts. Proprietary interconnect and cooling system.

Re: Apollo 11 vs. USB-C Chargers (2020)

#186

Post by kragen »

eru wrote: post #156
kragen wrote: post #92

Earlier quoted context omitted.

i think it's (unintentionally) misleading to describe analog 'computers' as 'computers'. what distinguishes digital computers from other digital hardware is that they're turing-complete (if given access to enough memory), and there isn't any similar notion in the analog domain the only reason they have the same name is that they were both originally built to replace people cranking out calculations on mechanical desk…

Most digital computers are Turing complete, but interestingly not all programming languages are Turing complete. Turing completeness is a tar pit that makes your code hard to analyse and optimise. It's an interesting challenge to find languages that allow meaningful and useful computation that are not Turing complete. Regular expressions and SQL-style relational algebra (but not Perl-style regular expressions nor mos…

yes, total functional programming is an interesting research area, and of course almost all of our subroutines are intended to verifiably terminate

Re: Apollo 11 vs. USB-C Chargers (2020)

#187

Post by kragen »

eesmith wrote: post #130
kragen wrote: post #123

Earlier quoted context omitted.

let me preface this with the disclaimer that i am far from an expert on the topic probably numerous eddies in natural turbulent fluid flows have been digital turing-complete computers, given what we know now about the complexity of turbulence and the potential simplicity of turing-complete behavior. but is there an objective, rather than subjective, way to define this? how complicated are our input-preparation and ou…

> is the game? Sure. One of the "Surprisingly Turing-Complete" examples is that "Magic: the Gathering: not just TC, but above arithmetic in the hierarchy ". See https://arxiv.org/abs/1904.09828 for the preprint "Magic: The Gathering is Turing Complete", https://arstechnica.com/science/2019/06/its-possible-to-buil... for an Ars Technica article, and https://hn.algolia.com/?q=magic+turing for the many HN submissions on…

mtg is more recent than things like the johnniac, but plausibly there's a traditional card game with the same criteria that predates electronic computation

but then we have to ask thorny ontological questions: does a card game count if it requires a particular configuration to be turing-complete, but nobody ever played it in that configuration? what if nobody ever played the game at all? what if nobody even knew the rules?

Re: Apollo 11 vs. USB-C Chargers (2020)

#188

Post by hinkley »

denton-scratch wrote: post #168
KMag wrote: post #76

Earlier quoted context omitted.

For the Apollo Guidance Computer, changing the program meant manually re-weaving wires through or around tiny magnet rings. A good part of the cost of the computer was the time spent painstakingly weaving the wires to store the program.

Pardon me, but why would you have to re-weave wires around magnetic rings? The magnetic rings are for storing data; the whole point is that you can change the data without rewiring the memory. If you have to re-wire permanent storage (e.g. program storage), that's equivalent to creating a mask ROM, which is basically just two funny-shaped sheets of conductor. There's no need for magnetic rings.

Because it’s not RAM, it’s ROM.

Re: Apollo 11 vs. USB-C Chargers (2020)

#189

Post by hinkley »

winrid wrote: post #86
lmm wrote: post #73

Earlier quoted context omitted.

Yes - up until a few years ago it was easy to find by googling, but now google has degraded to the point where I can't manage it.

Do you mean this? https://spritesmods.com/?art=hddhack&page=1 Searched "run linux on hard drive without cpu or ram" on Google - third result.

Not everyone gets the same results.

The closest I could find - with your search query - was #6, and it’s a Reddit conversation that contains this link. I don’t usually click on Reddit links.

If you use DDG it’s nowhere to be found.

Re: Apollo 11 vs. USB-C Chargers (2020)

#190

Post by hinkley »

Dah00n wrote: post #153
lmm wrote: post #73

Earlier quoted context omitted.

Yes - up until a few years ago it was easy to find by googling, but now google has degraded to the point where I can't manage it.

Yeah sure, people on HN says this all the time, but in reality it isn't true like a lot of comments getting repeated on here. I found it on the first try.

I’ve tried many times to find it. Don’t be an ass. As I told your more helpful compatriot, not everyone gets the same results.
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