13 ms·

Apollo 11 vs. USB-C Chargers (2020)

502 points by raimue 3y ago

kristopolous 3y ago
When we go back to the moon, I wouldn't be surprised if Zilog-Z80s were a major part of the hardware. Well known, well understood, predictable hardware goes a long way. There's a bunch of other considerations in outer space and z80s have proven robust and reliable there. Also I'd expect a bunch of Kermit and Xmodem to be used as well.
- monocasa 3y ago
  I'm not sure if there's a RAD hard z80 variant. They've got their own chips and protocols going back just as far, like https://en.wikipedia.org/wiki/MIL-STD-1553 https://en.wikipedia.org/wiki/MIL-STD-1553
  - kristopolous 3y ago
    The space shuttle used both z80 and 8086 until it ended in 2011. The international space station runs on among other chips, 80386SX-20s. IBM/BAE also has a few RADs based on POWER chips.
    - monocasa 3y ago
      Do you have a citation for that? The Space Shuttle Avionics System top level documentation specifically calls out having "no Z80's, 8086s, 68000's, etc." https://ntrs.nasa.gov/api/citations/19900015844/downloads/19900015844.pdf https://ntrs.nasa.gov/api/citations/19900015844/downloads/19...
      - kristopolous 3y ago
        Intel claims they did. https://twitter.com/intel/status/497927245672218624?lang=en https://twitter.com/intel/status/497927245672218624?lang=en although what's that word "some" doing in there... And also, sigh, to demonstrate once again that when I worked in space it was 20 years ago, https://www.nytimes.com/2002/05/12/us/for-parts-nasa-boldly-goes-on-ebay.html https://www.nytimes.com/2002/05/12/us/for-parts-nasa-boldly-... (https://web.archive.org/web/20230607141742/https://www.nytimes.com/2002/05/12/us/for-parts-nasa-boldly-goes-on-ebay.html https://web.archive.org/web/20230607141742/https://www.nytim...) Knowing how 8086 timing and interrupts worked was still important for what I was doing in the early 2000s. I don't pretend to remember any of it these days.
- dogma1138 3y ago
  I doubt so and if they will they’ll be abstracted to hell behind modern commodity hardware, Apollo had no bias when it comes to HDI/MMIs so astronauts could be trained on the computer interface that was possible at the time. The reason why the controls of Dragon and Orion look the way they do is that they are no far off from modern digital cockpits of jets like the F-22 and F-35 and everyone is used to graphical interfaces and touch controls. Having non intuitive interfaces that go against the bias astronauts and later on civilian contractors already have by using such interfaces over the past 2 decades will be detrimental to overall mission success. The other reason for why they’ll opt to use commodity hardware is that if we are going back to space for real now you need to be able to build and deploy systems at an ever increasing pace. We have enough powerful human safety rated hardware from aerospace and automotive there is no need to dig up relics. And lastly you’ll be hard pressed to find people who still know how to work with such legacy hardware at scale and unless we will drastically change the curriculum of computer science degrees around the US and the world that list would only get smaller each year. We’re far more likely to see ARM and RISC-V in space than z80’s.
- GlenTheMachine 3y ago
  They won’t be. We will use RAD750’s, the flight qualified variant of the PowerPC architecture. That’s the standard high end flight processor. https://www.petervis.com/Vintage%20Chips/PowerPC%20750/RAD750.html https://www.petervis.com/Vintage%20Chips/PowerPC%20750/RAD75... The next generation (at least according to NASA) will be RISC-V variants: https://www.zdnet.com/article/nasa-has-chosen-these-cpus-to-power-its-next-generation-of-spaceflight-computers/ https://www.zdnet.com/article/nasa-has-chosen-these-cpus-to-...
  - kristopolous 3y ago
    The 750 is still based on a 27 year old chip and runs at half its clockspeed. The point was that spaceflight is relatively computationally modest.
    - demondemidi 3y ago
      Reliability is more important. Even more problematic is that many semi companies have been funneled into just a few due decades of mergers. And all of these are chasing profits which means jettisoning RAD hard mil spec devices. Up until the early 2000s intel was still making hardened versions of the 386, now they make no milspec parts.
  - johnwalkr 3y ago
    I wouldn't call it the standard, it's just used in designs with legacy to avoid the huge cost of re-qualification of hardware and software. It's infeasible a lot of times due to cost and power consumption. I work in the private sector in space (lunar exploration actually) and everyone is qualifying normal/automotive grade stuff, or using space-grade microcontrollers for in-house designs, with everything from 8-32bit, [1] and ready-made cpu boards[2] for more complex use cases. I'm sharing just 2 examples but there are hundreds, with variations on redundancy implemented in all kinds of ways too, such as in software, on multiple cores, on multiple chips, or on multiple soft-cpu cores on a single or multiple FPGAs. [1] Example: https://www.militaryaerospace.com/computers/article/16726923/radiationhardened-microcontroller-for-space-satellites-introduced-by-microchip-technology https://www.militaryaerospace.com/computers/article/16726923... [2] Example: https://xiphos.com/product-details/q8 https://xiphos.com/product-details/q8
- johnwalkr 3y ago
  I work in this space and z80, kermit and xmodem are not part of the solution. Just because this stuff is simple to the user doesn't mean it's the best suited, and there's a whole industry working on this since the Z80 days. You can buy space-qualified microcontroller boards/components with anything from a simple 8 bit microcontroller to a 64-bit, multicore, 1Ghz+ ARM cpu depending on the use case. I'm sure Z80 has been used in space, but in my time in the industry I've never heard of it. Kermit and xmodem probably aren't what you want to use, they are actually a higher level than what is normally used and would require a big overhead, if they even worked at all with latencies that can reach 5-10s. Search for the keyword "CCSDS" to get hints about data protocols used in space.
  - kristopolous 3y ago
    I worked in it 20 years ago building diagnostic and networking tools ... arm was certainly around but there was also what I talked about. Things probably changed since then. Here's kermit in space ... coincidentally in a 20 year old article. Software I wrote supported diagnosing kermit errors. https://www.spacedaily.com/news/iss-03zq.html https://www.spacedaily.com/news/iss-03zq.html I guess now I'm old.
    - johnwalkr 3y ago
      Thanks for the reference! Kermit could be used locally on ISS or in a lunar mission now that I think about it, but so is/could SSH, web browsers or any modern technology. But most space exploration is robotic and depends on communication to ground stations on Earth, and that is fairly standardized. Perhaps kermit will be used on the lunar surface, and that will be a simplification compared to a web browser interface. But for communication to/from Earth and Moon, there are standards in place and it would be a complication, not simplification to add such a protocol.
      - kristopolous 3y ago
        oh who knows ... I stopped working on that stuff in I think 2006. The big push then was over to CAN and something called AFDX which worked over ethernet. I was dealing with octal and bcd daily, mid 2000s. I have no idea if people still use ARINC-429 or IRIG-B. Embedded RTOS was all proprietary back then for instance, like with VXWORKS. I'm sure it's not any more. I hated vxworks.
- atleta 3y ago
  It seems it's going to be a new, RISC-V based chip: [1] https://www.zdnet.com/article/nasa-has-chosen-these-cpus-to-power-its-next-generation-of-spaceflight-computers/ https://www.zdnet.com/article/nasa-has-chosen-these-cpus-to-... [2] https://www.nasa.gov/news-release/nasa-awards-next-generation-spaceflight-computing-processor-contract/ https://www.nasa.gov/news-release/nasa-awards-next-generatio...
nolroz 3y ago
Hi Forrest!
m463 3y ago
It is amazing they were able to miniaturize a computer to fix into a spaceship. Previously calculators were a room full of people, all of which required food, shelter, clothing and ... oxygen.
orliesaurus 3y ago
54 years ago - wow - was the Apollo 11 Moon Landing Guidance Computer (AGC) chip the best tech had to offer back then?
- GlenTheMachine 3y ago
  Yes, given the size, power, and reliability constraints. There were, of course, far more powerful computers around… but not ones you could fit in a spacecraft the size of a Volkswagen Beetle. The Apollo program consumed something like half of the United States’ entire IC fabrication capacity for a few years. https://www.bbc.com/future/article/20230516-apollo-how-moon-missions-changed-the-modern-world# https://www.bbc.com/future/article/20230516-apollo-how-moon-...
  - db48x 3y ago
    The AGC was 2 ft³. I believe the volume was written into the contract for development of the computer, and was simply a verbal guess by the owner of the company during negotiations. On the other hand, they had been designing control systems for aircraft and missiles for over a decade at that point so it was not an entirely uninformed guess. The amazing thing is that they did manage to make it fit into 2 ft³, even though the integrated circuits it used had not yet been invented when the contract was written.
- dgacmu 3y ago
  Yes when accounting for size. If you wanted something that was the size of a refrigerator, you could buy a data general Nova in 1969: https://en.m.wikipedia.org/wiki/Data_General_Nova https://en.m.wikipedia.org/wiki/Data_General_Nova 8KB of RAM! But hundreds of pounds vs 70lb for the AGC with fairly comparable capability (richer instructions/registers, lower initial clock rate). The AGC was quite impressive in terms of perf/weight
- kens 3y ago
  The Apollo Guidance Computer was the best technology when it was designed, but it was pretty much obsolete by the time of the Moon landing in 1969. Even by 1967, IBM's 4 Pi aerospace computer was roughly twice as fast and half the size, using TTL integrated circuits rather than the AGC's RTL NOR gates.
AnotherGoodName 3y ago
Pretty much all USB chips have a fully programmable CPU when you go into the data sheets. It feels silly for simple hid or charging devices but basic microcontrollers are cheap and actually save costs compared to asics.
- hinkley 3y ago
  I still want to see postgres or sqlite running straight on a storage controller some day. They probably don’t have enough memory to do it well though.
  - lmm 3y ago
    Booting Linux on a hard drive was what, 15 years ago now?
    - hinkley 3y ago
      Have you ever tried to google that?
      - lmm 3y ago
        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.
        Dah00n 3y ago
        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.
        hinkley 3y ago
        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.
vlovich123 3y ago
Is the weight/cost calculus sufficiently improved now that it’s cheaper to shield the processor in it’s entirety rather than trying to rad harden the circuitry itself (much more expensive due to inability to use off the shelf parts & limits the ability to use newer tech)? If I recall correctly this was one of the areas being explored by the mars drone although not sure if Mars surface radiation concerns are different than what you would use in space.
- thebestmoshe 3y ago
  Isn’t this basically what SpaceX is doing? > The flight software is written in C/C++ and runs in the x86 environment. For each calculation/decision, the "flight string" compares the results from both cores. If there is a inconsistency, the string is bad and doesn't send any commands. If both cores return the same response, the string sends the command to the various microcontrollers on the rocket that control things like the engines and grid fins. https://space.stackexchange.com/a/9446/53026 https://space.stackexchange.com/a/9446/53026
  - jojobas 3y ago
    That sounds way too low. Modern fly-by-wire planes are said to have 12-way voting.
    - somethingsaid 3y ago
      If you read the link it’s actually two cpu cores on a single cpu die each returning a string. Then 3 of those cpus send the resulting string to the microprocessors which then weigh those together to choose what to do. So it’s 6 times redundant in actuality.
      - SV_BubbleTime 3y ago
        That’s not 6x though. It’s a more solid 3x or 3x+3y, which… if you had a power failure at a chip doesn’t take a 6x to make it 5x. It makes it 4x with the two remaining PHY units because two logical cores went down with one error. The x being physical units, and the y being CPUs in lockstep so that the software is confirmed to not bug out somewhere. It’s 6x for the calculated code portion only, but 3x for CPU and 1-3x for power or solder or circuit board. I know it’s pretty pedantic, but I would call it the lowest form for any quality, which is likely 2-3x.
kens 3y ago
> Apollo 11 spacecraft contains 4 computers Analog computers don't get the respect they deserve. There's one more computer, the FCC. The Flight Control Computer is an analog computer in the Saturn V that controlled the rocket gimbals. It's a two-foot cylinder weighing almost 100 pounds.
- nothercastle 3y ago
  Exactly this. A lot of the systems had built in analog computers. It’s a lot cheaper to build then now with electronics but you need more computing power to do things that were previously done mechanically
  - hinkley 3y ago
    Analog computers have to be rebuilt if it turns out the program is wrong though, don’t they?
    - nothercastle 3y ago
      Yes though they tend to be mechanically tuned. So like a pneumatic computer or will get tuned to operate into some range of inputs and you probably bench prototype it before you mass produce it
    - coder543 3y ago
      In the context of this thread, I believe even a digital computer would have to be rebuilt if the program is wrong... :P Unless you typically salvage digital computers from the wreckage of a failed rocket test and stick it in the next prototype. If the FCC is wrong, kaboom.
      - scaredginger 3y ago
        I'm pretty sure you can perform tests and find defects without actually flying the rocket
        deleted 3y ago
ashvardanian 3y ago
Remarkable comparison! I'm surprised it had only one parity bit per 15-bit word. Even on Earth today we keep two parity bits per 8-bit word in most of our servers. > IBM estimated in 1996 that one error per month per 256 MiB of RAM was expected for a desktop computer. https://web.archive.org/web/20111202020146/https://www.newscientist.com/blog/technology/2008/03/do-we-need-cosmic-ray-alerts-for.html https://web.archive.org/web/20111202020146/https://www.newsc...
ssgodderidge 3y ago
> The Anker PowerPort Atom PD 2 USB-C Wall Charger CPU is 563 times faster than the Apollo 11 Guidance Computer Wild to think the thing that charges my devices could be programmed to put a human on the moon
- oldgradstudent 3y ago
  > Wild to think the thing that charges my devices could be programmed to put a human on the moon With a large enough lithium battery, a charger can easily take you part of the way there.
- fuzzfactor 3y ago
  The proven way to fly people to the moon and back using such low-powered computers was to have a supporting cast of thousands who were naturally well qualified using their personal slide rules to smoothly accomplish things that many of today's engineers would stumble over using their personal computers. Plenty of engineers on the ground had no computers, and the privileged ones who did had mainframes, not personal at all. A computer was too valuable to be employed doing anything that didn't absolutely need a computer, most useful for precision or speed of calculation. But look what happens when you give something like a mainframe to somebody who is naturally good at aerospace when using a slide rule to begin with.
- Someone 3y ago
  From that data point, we don’t know for sure. The Apollo Guidance Computer was programmed to put a human on the moon, but never used to actually do it, so no computer ever “put a human on the moon”. All landings used “fly by wire”, with an astronaut at the stick, and the thrusters controlled by software. https://www.quora.com/Could-the-Apollo-Guidance-Computer-have-landed-on-the-moon-itself-or-did-a-man-have-to-be-in-control-during-that-stage https://www.quora.com/Could-the-Apollo-Guidance-Computer-hav...: “P64. At about 7,000 feet altitude (a point known as “high gate”), the computer switched automatically to P64. The computer was still doing all the flying, and steered the LM toward its landing target. However, the Commander could look at the landing site, and if he didn’t like it, could pick a different target and the computer would alter its course and steer toward that target. At this point, they were to use one of three programs to complete the landing: P66. This was the program that was actually used for all six lunar landings. A few hundred feet above the surface the Commander told the computer to switch to P66. This is what was commonly known as “manual mode”, although it wasn’t really. In this mode, the Commander steered the LM by telling the computer what he wanted to do, and the computer made it happen. This continued through landing. P65. Here’s the automatic mode you asked about. If the computer remained in P64 until it was about 150 feet above the surface, then the computer automatically switched to P65, which took the LM all the way to the surface under computer control. The problem is that the computer had no way to look for obstacles or tell how level its target landing site was. On every flight, the Commander wanted to choose a different spot than where the computer was taking the LM, and so the Commander switched to P66 before the computer automatically switched to P65. [Update: The code for P65 was removed from the AGC on later flights. The programmers needed memory for additional code elsewhere, and the AGC was so memory-constrained that adding code one place meant removing something else. By that point it was obvious that none of the crews was ever going to use the automatic landing mode, so P65 was removed.] P67. This is full-on honest-to-goodness manual mode. In P66, even though the pilot is steering, the computer is still in the loop. In P67, the computer is totally disengaged. It is still providing data, such as altitude and descent rate, but has no control over the vehicle.”
codezero 3y ago
Weird question maybe, but does anyone keep track of quantitative or qualitative data that measures the discrepancy between consumer (commercial) and government computer technology? TBH, it's kind of amazing that a custom computer from 50 years ago has the specs of a common IC/SoC today, but those specs scale with time.
- ajsnigrutin 3y ago
  There is no difference anymore, the only difference is the scale. Back then, consumers got nothing, governments got largge computers (room sized+), then consumers got microcomputers (desktop sized), governments got larger mainframes, consumers got PCs, government got big-box supercomputers,... And now? Consumers get x86_64 servers, governments get x86_64 servers, and the only difference is how much money you have, how many servers can you buy and how much space, energy and cooling you need to run them. well, "normal users" get laptops and smartphones, but geek-consumers buy servers... and yeah, I know arm is an alternative.
  - codezero 3y ago
    I was asking about anyone tracking the disparity between nation-state computing power and commercially available computing power. This seems like something that's uncontroversial.
    - creer 3y ago
      "Nation state" doesn't mean "country". It certainly doesn't mean "rich country".
  - tavavex 3y ago
    I'd argue that the difference is the price. There is still quite a bit of a difference between average consumer and business hardware, but compute power is cheap enough that the average person can afford what was previously only reserved for large companies. The average "consumer computer" nowadays is an ARM smartphone, and while server equipment is purchasable, you can't exactly hit up your local electronics store to buy a server rack or a server CPU. You can still get those things quite easily, but I wouldn't say their main goal is being sold to individuals.
jackhack 3y ago
it's a fun article, but I would liked to have seen at least a brief mention of power consumption comparison among the four designs.
jcalvinowens 3y ago
>> others point out that the LVDC actually contains triply-redundant logic. The logic gives 3 answers and the voting mechanism picks the winner. This is a very minor point... but three of something isn't triple redundancy: it's double redundancy. Two is single redundancy, one is no redundancy. Unless the voting mechanism can somehow produce a correct answer from differing answers from all three implementations of the logic, I don't understand how it could be considered triply redundant. Is the voting mechanism itself functionally a fourth implementation?
- deleted 3y ago
  [deleted]
- kens 3y ago
  The official name for the LVDC's logic is triple modular redundant (TMR). The voting mechanism simply picks the majority, so it can tolerate one failure. The LVDC is a serial computer, which makes voting simpler to implement, since you're only dealing with one bit at a time.
- somat 3y ago
  I find it fascinating the two different schools of thought exposed in the LVDC and the AGC. The LVDC was a highly redundant can not fail design. the AGC had no redundancy and was designed to recover quickly if failure occurred.
SV_BubbleTime 3y ago
>But it is another step toward increasing complexity. I wish more people understood this, and could better see the coming crisis.
dang 3y ago
Discussed at the time (of the article): Apollo 11 Guidance Computer vs. USB-C Chargers - https://news.ycombinator.com/item?id=22254719 https://news.ycombinator.com/item?id=22254719 - Feb 2020 (205 comments)
daxfohl 3y ago
So in 50 years the equivalent of a gpt4 training cluster from today's datacenters will fit in a cheap cable, and it will run over 100 times faster than a full cluster today.
- FredPret 3y ago
  Computronium
- ko27 3y ago
  Yeap, that's how exponential growth works. It just never stops.
- daxfohl 3y ago
  I'd say even more impressive is that, given an ARM Cortex X4 runs at almost 100x the clock speed, up to 14 cores, has caches, branch prediction, floating point, specialized instructions, gpu, etc., it's probably 100000 times faster than the CYPD4225. So given GPT4 training took ~100 days, it means a typical cell phone equivalent in 50 years will be able to train a GPT4 equivalent from scratch in under a second.
  - daxfohl 3y ago
    What hardware giveth, software taketh away. JS frameworks of the 2070s will find some reason to fully retrain an LLM on each keypress.
Tommstein 3y ago
Too bad the link to Jonny Kim's biography is broken (one that works: https://www.nasa.gov/people/jonny-kim/ https://www.nasa.gov/people/jonny-kim/). He has to be one of the most impressive humans who has ever lived. Amongst other things, a decorated Navy SEAL, Harvard medical doctor, and astronaut. Sounds like a kid slapping together the ultimate G.I. Joe.
tavavex 3y ago
I'm curious - are there any ways of finding out the precise hardware that's used in these small-scale devices that are generally not considered to be computers (like smartphone chargers) without actually having to take them apart? Are there special datasheets, or perhaps some documents for government certification, or anything like it? I've always been fascinated with the barebones, low-spec hardware that runs mundane electronic things, so I want to know where the author got all that information from.
- AnotherGoodName 3y ago
  Generally no but taking them apart to look at the chips inside is easy. Fwiw everything has a CPU in it these days. Actually that's been true since the 70s. Your old 1970's keyboard had a fully programmable CPU in it. Typically an Intel MCS-48 variant https://en.wikipedia.org/wiki/Intel_MCS-48#Uses https://en.wikipedia.org/wiki/Intel_MCS-48#Uses Today it's even more the case. You have fully programmable CPUs in your keyboard, trackpad, mouse, all usb devices, etc.
- ArcticLandfall 3y ago
  Wireless devices go through an FCC certification process that publishes teardowns. And iFixit posts.
Klaster_1 3y ago
Can you run Doom on a USB-C charger? Did anyone manage to?
- yjftsjthsd-h 3y ago
  I feel like I/O would be the real pain point there. I suppose if you throw out performance you could forward X/VNC/whatever over serial (possibly with TCP/IP in the middle; SLIP is ugly but so flexible), but that's unlikely to be playable.
somat 3y ago
The ariicle was a lot of fun however I felt it missed a important aspect about the respective computers. IO channels. I don't know about the USB charge controllers. But the AGC as a flight computer had a bunch of inputs and outputs. Does a Richtek RT7205 have enough IO?
- jiggawatts 3y ago
  The most powerful chip in the list (Cypress CYPD4126) has 30x general purpose I/O pins.[1] AFAIK, this is typical of USB controller chips, which generally have about 20-30 I/O pins, but I’m sure there are outliers. The AGC seems to have four 16-bit input registers, and five 16-bit output registers[2], for a total of 144 I/O pins total. [1] https://ta.infinity-component.com/datasheet/9c-CYPD4126-40LQXI.pdf https://ta.infinity-component.com/datasheet/9c-CYPD4126-40LQ... [2] https://en.wikipedia.org/wiki/Apollo_Guidance_Computer#Other_registers https://en.wikipedia.org/wiki/Apollo_Guidance_Computer#Other...
- theon144 3y ago
  I have no clue as to the I/O requirements of the AGC, but I imagine that with ~500x the performance, a simple I/O expander could fill the gap?
continuational 3y ago
Seems like with cables this powerful, it might make sense for some devices to simply run their logic on the cable CPU, instead of coming with their own.
ReptileMan 3y ago
The great thing about the AI age is that we are once again performance constrained so people start to rediscover the lost art of actually optimizing a program or runtime (the last such age were the waning days of ps2. Those guys made GoW 2 run on 32 megs of ram ... respect)
blauditore 3y ago
I'm a bit tired of all the sensationalist "look what landed on the moon vs. today's hardware" comparisons. The first airplanes didn't have any sort of computer on board, so computation power is not the single deciding factor on the performance and success of such an endeavor. The software (and hardware) of the Apollo missions was very well-engineered. We all know computation became ridiculously more powerful in the meantime, but that wouldn't make it easy to do the same nowadays. More performance doesn't render the need for good engineering obsolete (even though some seem to heavily lean on that premise).
- BSDobelix 3y ago
  >first airplanes didn't have any sort of computer on board, Sure they had and often still have, it's called wetware. >so computation power is not the single deciding factor on the performance and success of such an endeavor The endeavor to charge a phone?
- hnlmorg 3y ago
  I don’t think you’re reading these articles in the right spirit if that’s your take away from them. What I find more interesting is to compare how complicated the tech we don’t think about has become. It’s amazing that a cable, not a smart device or even 80s digital watch, but a literal cable, has as much technology packed into it as Apollo 11 and we don’t even notice. Playing devils advocate for your comment, one of the (admittedly many) reasons going to the moon is harder than charging a USB device is because there are not off-the-shelf parts for space travel. If you had to build your USB charger from scratch (including defining the USB specification for the first time) each time you needed to charge your phone, I bet people would quickly talk about USB cables as a “hard problem” too. That is the biggest takeaway we should get from articles like this. Not that Apollo 11 wasn’t a hugely impressive feat of engineering. But that there is an enormous amount of engineering in our every day lives that is mass produced and we don’t even notice.
  - argiopetech 3y ago
    This is actually about the wall warts the cable could be plugged into. Otherwise, I completely agree.
cubefox 3y ago
If anyone is interested, there is a 1965 documentary about an Apollo computer: https://youtube.com/watch?v=ndvmFlg1WmE https://youtube.com/watch?v=ndvmFlg1WmE
Havoc 3y ago
It has certainly felt like the limit is software/PEBKAC for a long while. Until lately with LLMs...that does make me feel "wish I had a bigger hammer" again.
denton-scratch 3y ago
> the LVDC actually contains triply-redundant logic I didn't know that was just for the LVDC. > emulate this voting scheme with 3x microcontrollers with a 4th to tally votes will not make the system any more reliable I think that's clear enough; the vote-tallier becomes a SPOF. I'm not sure how Tandem and Stratus handled discrepancies between their (twin) processors. Stratus used a pair of OTC 68K processors, which doesn't seem to mean voting; I can't see how you'd resolve a disagreement between just two voters. I can't see how you make a voting-based "reliable" processor from OTC CPU chips; I imagine it would require each CPU to observe the outputs of the other two, and tell itself to stop voting if it loses a ballot. Which sounds to me like custom CPU hardware. Any external hardware for comparing votes, telling a CPU to stop voting, and routing the vote-winning output, amounts to a vote-tallier, which is a SPOF. You could have three vote-talliers, checking up on one-another; but then you'd need a vote-tallier-tallier. It's turtles from then on down. In general, having multiple CPUs voting as a way of improving reliability seems fraught, because it increases complexity, which reduces reliability. Maybe making reliable processors amounts to just making processors that you can rely on.
- ryukoposting 3y ago
  > I can't see how you'd resolve a disagreement between just two voters. Tell them both to run the calculation again, perhaps?
simne 3y ago
> 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.
Rip_adam434 3y ago
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Rip_adam434 3y ago
[flagged]

502 points by raimue 3y ago

When we go back to the moon, I wouldn't be surprised if Zilog-Z80s were a major part of the hardware. Well known, well understood, predictable hardware goes a long way. There's a bunch of other considerations in outer space and z80s have proven robust and reliable there. Also I'd expect a bunch of Kermit and Xmodem to be used as well.

monocasa 3y ago
I'm not sure if there's a RAD hard z80 variant. They've got their own chips and protocols going back just as far, like https://en.wikipedia.org/wiki/MIL-STD-1553 https://en.wikipedia.org/wiki/MIL-STD-1553
- kristopolous 3y ago
  The space shuttle used both z80 and 8086 until it ended in 2011. The international space station runs on among other chips, 80386SX-20s. IBM/BAE also has a few RADs based on POWER chips.
  - monocasa 3y ago
    Do you have a citation for that? The Space Shuttle Avionics System top level documentation specifically calls out having "no Z80's, 8086s, 68000's, etc." https://ntrs.nasa.gov/api/citations/19900015844/downloads/19900015844.pdf https://ntrs.nasa.gov/api/citations/19900015844/downloads/19...
    - kristopolous 3y ago
      Intel claims they did. https://twitter.com/intel/status/497927245672218624?lang=en https://twitter.com/intel/status/497927245672218624?lang=en although what's that word "some" doing in there... And also, sigh, to demonstrate once again that when I worked in space it was 20 years ago, https://www.nytimes.com/2002/05/12/us/for-parts-nasa-boldly-goes-on-ebay.html https://www.nytimes.com/2002/05/12/us/for-parts-nasa-boldly-... (https://web.archive.org/web/20230607141742/https://www.nytimes.com/2002/05/12/us/for-parts-nasa-boldly-goes-on-ebay.html https://web.archive.org/web/20230607141742/https://www.nytim...) Knowing how 8086 timing and interrupts worked was still important for what I was doing in the early 2000s. I don't pretend to remember any of it these days.
dogma1138 3y ago
I doubt so and if they will they’ll be abstracted to hell behind modern commodity hardware, Apollo had no bias when it comes to HDI/MMIs so astronauts could be trained on the computer interface that was possible at the time. The reason why the controls of Dragon and Orion look the way they do is that they are no far off from modern digital cockpits of jets like the F-22 and F-35 and everyone is used to graphical interfaces and touch controls. Having non intuitive interfaces that go against the bias astronauts and later on civilian contractors already have by using such interfaces over the past 2 decades will be detrimental to overall mission success. The other reason for why they’ll opt to use commodity hardware is that if we are going back to space for real now you need to be able to build and deploy systems at an ever increasing pace. We have enough powerful human safety rated hardware from aerospace and automotive there is no need to dig up relics. And lastly you’ll be hard pressed to find people who still know how to work with such legacy hardware at scale and unless we will drastically change the curriculum of computer science degrees around the US and the world that list would only get smaller each year. We’re far more likely to see ARM and RISC-V in space than z80’s.
GlenTheMachine 3y ago
They won’t be. We will use RAD750’s, the flight qualified variant of the PowerPC architecture. That’s the standard high end flight processor. https://www.petervis.com/Vintage%20Chips/PowerPC%20750/RAD750.html https://www.petervis.com/Vintage%20Chips/PowerPC%20750/RAD75... The next generation (at least according to NASA) will be RISC-V variants: https://www.zdnet.com/article/nasa-has-chosen-these-cpus-to-power-its-next-generation-of-spaceflight-computers/ https://www.zdnet.com/article/nasa-has-chosen-these-cpus-to-...
- kristopolous 3y ago
  The 750 is still based on a 27 year old chip and runs at half its clockspeed. The point was that spaceflight is relatively computationally modest.
  - demondemidi 3y ago
    Reliability is more important. Even more problematic is that many semi companies have been funneled into just a few due decades of mergers. And all of these are chasing profits which means jettisoning RAD hard mil spec devices. Up until the early 2000s intel was still making hardened versions of the 386, now they make no milspec parts.
- johnwalkr 3y ago
  I wouldn't call it the standard, it's just used in designs with legacy to avoid the huge cost of re-qualification of hardware and software. It's infeasible a lot of times due to cost and power consumption. I work in the private sector in space (lunar exploration actually) and everyone is qualifying normal/automotive grade stuff, or using space-grade microcontrollers for in-house designs, with everything from 8-32bit, [1] and ready-made cpu boards[2] for more complex use cases. I'm sharing just 2 examples but there are hundreds, with variations on redundancy implemented in all kinds of ways too, such as in software, on multiple cores, on multiple chips, or on multiple soft-cpu cores on a single or multiple FPGAs. [1] Example: https://www.militaryaerospace.com/computers/article/16726923/radiationhardened-microcontroller-for-space-satellites-introduced-by-microchip-technology https://www.militaryaerospace.com/computers/article/16726923... [2] Example: https://xiphos.com/product-details/q8 https://xiphos.com/product-details/q8
johnwalkr 3y ago
I work in this space and z80, kermit and xmodem are not part of the solution. Just because this stuff is simple to the user doesn't mean it's the best suited, and there's a whole industry working on this since the Z80 days. You can buy space-qualified microcontroller boards/components with anything from a simple 8 bit microcontroller to a 64-bit, multicore, 1Ghz+ ARM cpu depending on the use case. I'm sure Z80 has been used in space, but in my time in the industry I've never heard of it. Kermit and xmodem probably aren't what you want to use, they are actually a higher level than what is normally used and would require a big overhead, if they even worked at all with latencies that can reach 5-10s. Search for the keyword "CCSDS" to get hints about data protocols used in space.
- kristopolous 3y ago
  I worked in it 20 years ago building diagnostic and networking tools ... arm was certainly around but there was also what I talked about. Things probably changed since then. Here's kermit in space ... coincidentally in a 20 year old article. Software I wrote supported diagnosing kermit errors. https://www.spacedaily.com/news/iss-03zq.html https://www.spacedaily.com/news/iss-03zq.html I guess now I'm old.
  - johnwalkr 3y ago
    Thanks for the reference! Kermit could be used locally on ISS or in a lunar mission now that I think about it, but so is/could SSH, web browsers or any modern technology. But most space exploration is robotic and depends on communication to ground stations on Earth, and that is fairly standardized. Perhaps kermit will be used on the lunar surface, and that will be a simplification compared to a web browser interface. But for communication to/from Earth and Moon, there are standards in place and it would be a complication, not simplification to add such a protocol.
    - kristopolous 3y ago
      oh who knows ... I stopped working on that stuff in I think 2006. The big push then was over to CAN and something called AFDX which worked over ethernet. I was dealing with octal and bcd daily, mid 2000s. I have no idea if people still use ARINC-429 or IRIG-B. Embedded RTOS was all proprietary back then for instance, like with VXWORKS. I'm sure it's not any more. I hated vxworks.
atleta 3y ago
It seems it's going to be a new, RISC-V based chip: [1] https://www.zdnet.com/article/nasa-has-chosen-these-cpus-to-power-its-next-generation-of-spaceflight-computers/ https://www.zdnet.com/article/nasa-has-chosen-these-cpus-to-... [2] https://www.nasa.gov/news-release/nasa-awards-next-generation-spaceflight-computing-processor-contract/ https://www.nasa.gov/news-release/nasa-awards-next-generatio...

nolroz 3y ago

Hi Forrest!

m463 3y ago

It is amazing they were able to miniaturize a computer to fix into a spaceship. Previously calculators were a room full of people, all of which required food, shelter, clothing and ... oxygen.

orliesaurus 3y ago

54 years ago - wow - was the Apollo 11 Moon Landing Guidance Computer (AGC) chip the best tech had to offer back then?

GlenTheMachine 3y ago
Yes, given the size, power, and reliability constraints. There were, of course, far more powerful computers around… but not ones you could fit in a spacecraft the size of a Volkswagen Beetle. The Apollo program consumed something like half of the United States’ entire IC fabrication capacity for a few years. https://www.bbc.com/future/article/20230516-apollo-how-moon-missions-changed-the-modern-world# https://www.bbc.com/future/article/20230516-apollo-how-moon-...
- db48x 3y ago
  The AGC was 2 ft³. I believe the volume was written into the contract for development of the computer, and was simply a verbal guess by the owner of the company during negotiations. On the other hand, they had been designing control systems for aircraft and missiles for over a decade at that point so it was not an entirely uninformed guess. The amazing thing is that they did manage to make it fit into 2 ft³, even though the integrated circuits it used had not yet been invented when the contract was written.
dgacmu 3y ago
Yes when accounting for size. If you wanted something that was the size of a refrigerator, you could buy a data general Nova in 1969: https://en.m.wikipedia.org/wiki/Data_General_Nova https://en.m.wikipedia.org/wiki/Data_General_Nova 8KB of RAM! But hundreds of pounds vs 70lb for the AGC with fairly comparable capability (richer instructions/registers, lower initial clock rate). The AGC was quite impressive in terms of perf/weight
kens 3y ago
The Apollo Guidance Computer was the best technology when it was designed, but it was pretty much obsolete by the time of the Moon landing in 1969. Even by 1967, IBM's 4 Pi aerospace computer was roughly twice as fast and half the size, using TTL integrated circuits rather than the AGC's RTL NOR gates.

AnotherGoodName 3y ago

Pretty much all USB chips have a fully programmable CPU when you go into the data sheets. It feels silly for simple hid or charging devices but basic microcontrollers are cheap and actually save costs compared to asics.

hinkley 3y ago
I still want to see postgres or sqlite running straight on a storage controller some day. They probably don’t have enough memory to do it well though.
- lmm 3y ago
  Booting Linux on a hard drive was what, 15 years ago now?
  - hinkley 3y ago
    Have you ever tried to google that?
    - lmm 3y ago
      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.
      - Dah00n 3y ago
        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.
        hinkley 3y ago
        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.

vlovich123 3y ago

Is the weight/cost calculus sufficiently improved now that it’s cheaper to shield the processor in it’s entirety rather than trying to rad harden the circuitry itself (much more expensive due to inability to use off the shelf parts & limits the ability to use newer tech)? If I recall correctly this was one of the areas being explored by the mars drone although not sure if Mars surface radiation concerns are different than what you would use in space.

thebestmoshe 3y ago
Isn’t this basically what SpaceX is doing? > The flight software is written in C/C++ and runs in the x86 environment. For each calculation/decision, the "flight string" compares the results from both cores. If there is a inconsistency, the string is bad and doesn't send any commands. If both cores return the same response, the string sends the command to the various microcontrollers on the rocket that control things like the engines and grid fins. https://space.stackexchange.com/a/9446/53026 https://space.stackexchange.com/a/9446/53026
- jojobas 3y ago
  That sounds way too low. Modern fly-by-wire planes are said to have 12-way voting.
  - somethingsaid 3y ago
    If you read the link it’s actually two cpu cores on a single cpu die each returning a string. Then 3 of those cpus send the resulting string to the microprocessors which then weigh those together to choose what to do. So it’s 6 times redundant in actuality.
    - SV_BubbleTime 3y ago
      That’s not 6x though. It’s a more solid 3x or 3x+3y, which… if you had a power failure at a chip doesn’t take a 6x to make it 5x. It makes it 4x with the two remaining PHY units because two logical cores went down with one error. The x being physical units, and the y being CPUs in lockstep so that the software is confirmed to not bug out somewhere. It’s 6x for the calculated code portion only, but 3x for CPU and 1-3x for power or solder or circuit board. I know it’s pretty pedantic, but I would call it the lowest form for any quality, which is likely 2-3x.

kens 3y ago

> Apollo 11 spacecraft contains 4 computers Analog computers don't get the respect they deserve. There's one more computer, the FCC. The Flight Control Computer is an analog computer in the Saturn V that controlled the rocket gimbals. It's a two-foot cylinder weighing almost 100 pounds.

nothercastle 3y ago
Exactly this. A lot of the systems had built in analog computers. It’s a lot cheaper to build then now with electronics but you need more computing power to do things that were previously done mechanically
- hinkley 3y ago
  Analog computers have to be rebuilt if it turns out the program is wrong though, don’t they?
  - nothercastle 3y ago
    Yes though they tend to be mechanically tuned. So like a pneumatic computer or will get tuned to operate into some range of inputs and you probably bench prototype it before you mass produce it
  - coder543 3y ago
    In the context of this thread, I believe even a digital computer would have to be rebuilt if the program is wrong... :P Unless you typically salvage digital computers from the wreckage of a failed rocket test and stick it in the next prototype. If the FCC is wrong, kaboom.
    - scaredginger 3y ago
      I'm pretty sure you can perform tests and find defects without actually flying the rocket
      - deleted 3y ago

ashvardanian 3y ago

Remarkable comparison! I'm surprised it had only one parity bit per 15-bit word. Even on Earth today we keep two parity bits per 8-bit word in most of our servers. > IBM estimated in 1996 that one error per month per 256 MiB of RAM was expected for a desktop computer. https://web.archive.org/web/20111202020146/https://www.newscientist.com/blog/technology/2008/03/do-we-need-cosmic-ray-alerts-for.html https://web.archive.org/web/20111202020146/https://www.newsc...

ssgodderidge 3y ago

> The Anker PowerPort Atom PD 2 USB-C Wall Charger CPU is 563 times faster than the Apollo 11 Guidance Computer Wild to think the thing that charges my devices could be programmed to put a human on the moon

oldgradstudent 3y ago
> Wild to think the thing that charges my devices could be programmed to put a human on the moon With a large enough lithium battery, a charger can easily take you part of the way there.
fuzzfactor 3y ago
The proven way to fly people to the moon and back using such low-powered computers was to have a supporting cast of thousands who were naturally well qualified using their personal slide rules to smoothly accomplish things that many of today's engineers would stumble over using their personal computers. Plenty of engineers on the ground had no computers, and the privileged ones who did had mainframes, not personal at all. A computer was too valuable to be employed doing anything that didn't absolutely need a computer, most useful for precision or speed of calculation. But look what happens when you give something like a mainframe to somebody who is naturally good at aerospace when using a slide rule to begin with.
Someone 3y ago
From that data point, we don’t know for sure. The Apollo Guidance Computer was programmed to put a human on the moon, but never used to actually do it, so no computer ever “put a human on the moon”. All landings used “fly by wire”, with an astronaut at the stick, and the thrusters controlled by software. https://www.quora.com/Could-the-Apollo-Guidance-Computer-have-landed-on-the-moon-itself-or-did-a-man-have-to-be-in-control-during-that-stage https://www.quora.com/Could-the-Apollo-Guidance-Computer-hav...: “P64. At about 7,000 feet altitude (a point known as “high gate”), the computer switched automatically to P64. The computer was still doing all the flying, and steered the LM toward its landing target. However, the Commander could look at the landing site, and if he didn’t like it, could pick a different target and the computer would alter its course and steer toward that target. At this point, they were to use one of three programs to complete the landing: P66. This was the program that was actually used for all six lunar landings. A few hundred feet above the surface the Commander told the computer to switch to P66. This is what was commonly known as “manual mode”, although it wasn’t really. In this mode, the Commander steered the LM by telling the computer what he wanted to do, and the computer made it happen. This continued through landing. P65. Here’s the automatic mode you asked about. If the computer remained in P64 until it was about 150 feet above the surface, then the computer automatically switched to P65, which took the LM all the way to the surface under computer control. The problem is that the computer had no way to look for obstacles or tell how level its target landing site was. On every flight, the Commander wanted to choose a different spot than where the computer was taking the LM, and so the Commander switched to P66 before the computer automatically switched to P65. [Update: The code for P65 was removed from the AGC on later flights. The programmers needed memory for additional code elsewhere, and the AGC was so memory-constrained that adding code one place meant removing something else. By that point it was obvious that none of the crews was ever going to use the automatic landing mode, so P65 was removed.] P67. This is full-on honest-to-goodness manual mode. In P66, even though the pilot is steering, the computer is still in the loop. In P67, the computer is totally disengaged. It is still providing data, such as altitude and descent rate, but has no control over the vehicle.”

codezero 3y ago

Weird question maybe, but does anyone keep track of quantitative or qualitative data that measures the discrepancy between consumer (commercial) and government computer technology? TBH, it's kind of amazing that a custom computer from 50 years ago has the specs of a common IC/SoC today, but those specs scale with time.

ajsnigrutin 3y ago
There is no difference anymore, the only difference is the scale. Back then, consumers got nothing, governments got largge computers (room sized+), then consumers got microcomputers (desktop sized), governments got larger mainframes, consumers got PCs, government got big-box supercomputers,... And now? Consumers get x86_64 servers, governments get x86_64 servers, and the only difference is how much money you have, how many servers can you buy and how much space, energy and cooling you need to run them. well, "normal users" get laptops and smartphones, but geek-consumers buy servers... and yeah, I know arm is an alternative.
- codezero 3y ago
  I was asking about anyone tracking the disparity between nation-state computing power and commercially available computing power. This seems like something that's uncontroversial.
  - creer 3y ago
    "Nation state" doesn't mean "country". It certainly doesn't mean "rich country".
- tavavex 3y ago
  I'd argue that the difference is the price. There is still quite a bit of a difference between average consumer and business hardware, but compute power is cheap enough that the average person can afford what was previously only reserved for large companies. The average "consumer computer" nowadays is an ARM smartphone, and while server equipment is purchasable, you can't exactly hit up your local electronics store to buy a server rack or a server CPU. You can still get those things quite easily, but I wouldn't say their main goal is being sold to individuals.

jackhack 3y ago

it's a fun article, but I would liked to have seen at least a brief mention of power consumption comparison among the four designs.

jcalvinowens 3y ago

>> others point out that the LVDC actually contains triply-redundant logic. The logic gives 3 answers and the voting mechanism picks the winner. This is a very minor point... but three of something isn't triple redundancy: it's double redundancy. Two is single redundancy, one is no redundancy. Unless the voting mechanism can somehow produce a correct answer from differing answers from all three implementations of the logic, I don't understand how it could be considered triply redundant. Is the voting mechanism itself functionally a fourth implementation?

deleted 3y ago
[deleted]
kens 3y ago
The official name for the LVDC's logic is triple modular redundant (TMR). The voting mechanism simply picks the majority, so it can tolerate one failure. The LVDC is a serial computer, which makes voting simpler to implement, since you're only dealing with one bit at a time.
somat 3y ago
I find it fascinating the two different schools of thought exposed in the LVDC and the AGC. The LVDC was a highly redundant can not fail design. the AGC had no redundancy and was designed to recover quickly if failure occurred.

SV_BubbleTime 3y ago

>But it is another step toward increasing complexity. I wish more people understood this, and could better see the coming crisis.

dang 3y ago

Discussed at the time (of the article): Apollo 11 Guidance Computer vs. USB-C Chargers - https://news.ycombinator.com/item?id=22254719 https://news.ycombinator.com/item?id=22254719 - Feb 2020 (205 comments)

daxfohl 3y ago

So in 50 years the equivalent of a gpt4 training cluster from today's datacenters will fit in a cheap cable, and it will run over 100 times faster than a full cluster today.

FredPret 3y ago
Computronium
ko27 3y ago
Yeap, that's how exponential growth works. It just never stops.
daxfohl 3y ago
I'd say even more impressive is that, given an ARM Cortex X4 runs at almost 100x the clock speed, up to 14 cores, has caches, branch prediction, floating point, specialized instructions, gpu, etc., it's probably 100000 times faster than the CYPD4225. So given GPT4 training took ~100 days, it means a typical cell phone equivalent in 50 years will be able to train a GPT4 equivalent from scratch in under a second.
- daxfohl 3y ago
  What hardware giveth, software taketh away. JS frameworks of the 2070s will find some reason to fully retrain an LLM on each keypress.

Tommstein 3y ago

Too bad the link to Jonny Kim's biography is broken (one that works: https://www.nasa.gov/people/jonny-kim/ https://www.nasa.gov/people/jonny-kim/). He has to be one of the most impressive humans who has ever lived. Amongst other things, a decorated Navy SEAL, Harvard medical doctor, and astronaut. Sounds like a kid slapping together the ultimate G.I. Joe.

tavavex 3y ago

I'm curious - are there any ways of finding out the precise hardware that's used in these small-scale devices that are generally not considered to be computers (like smartphone chargers) without actually having to take them apart? Are there special datasheets, or perhaps some documents for government certification, or anything like it? I've always been fascinated with the barebones, low-spec hardware that runs mundane electronic things, so I want to know where the author got all that information from.

AnotherGoodName 3y ago
Generally no but taking them apart to look at the chips inside is easy. Fwiw everything has a CPU in it these days. Actually that's been true since the 70s. Your old 1970's keyboard had a fully programmable CPU in it. Typically an Intel MCS-48 variant https://en.wikipedia.org/wiki/Intel_MCS-48#Uses https://en.wikipedia.org/wiki/Intel_MCS-48#Uses Today it's even more the case. You have fully programmable CPUs in your keyboard, trackpad, mouse, all usb devices, etc.
ArcticLandfall 3y ago
Wireless devices go through an FCC certification process that publishes teardowns. And iFixit posts.

Klaster_1 3y ago

Can you run Doom on a USB-C charger? Did anyone manage to?

yjftsjthsd-h 3y ago
I feel like I/O would be the real pain point there. I suppose if you throw out performance you could forward X/VNC/whatever over serial (possibly with TCP/IP in the middle; SLIP is ugly but so flexible), but that's unlikely to be playable.

somat 3y ago

The ariicle was a lot of fun however I felt it missed a important aspect about the respective computers. IO channels. I don't know about the USB charge controllers. But the AGC as a flight computer had a bunch of inputs and outputs. Does a Richtek RT7205 have enough IO?

jiggawatts 3y ago
The most powerful chip in the list (Cypress CYPD4126) has 30x general purpose I/O pins.[1] AFAIK, this is typical of USB controller chips, which generally have about 20-30 I/O pins, but I’m sure there are outliers. The AGC seems to have four 16-bit input registers, and five 16-bit output registers[2], for a total of 144 I/O pins total. [1] https://ta.infinity-component.com/datasheet/9c-CYPD4126-40LQXI.pdf https://ta.infinity-component.com/datasheet/9c-CYPD4126-40LQ... [2] https://en.wikipedia.org/wiki/Apollo_Guidance_Computer#Other_registers https://en.wikipedia.org/wiki/Apollo_Guidance_Computer#Other...
theon144 3y ago
I have no clue as to the I/O requirements of the AGC, but I imagine that with ~500x the performance, a simple I/O expander could fill the gap?

continuational 3y ago

Seems like with cables this powerful, it might make sense for some devices to simply run their logic on the cable CPU, instead of coming with their own.

ReptileMan 3y ago

The great thing about the AI age is that we are once again performance constrained so people start to rediscover the lost art of actually optimizing a program or runtime (the last such age were the waning days of ps2. Those guys made GoW 2 run on 32 megs of ram ... respect)

blauditore 3y ago

I'm a bit tired of all the sensationalist "look what landed on the moon vs. today's hardware" comparisons. The first airplanes didn't have any sort of computer on board, so computation power is not the single deciding factor on the performance and success of such an endeavor. The software (and hardware) of the Apollo missions was very well-engineered. We all know computation became ridiculously more powerful in the meantime, but that wouldn't make it easy to do the same nowadays. More performance doesn't render the need for good engineering obsolete (even though some seem to heavily lean on that premise).

BSDobelix 3y ago
>first airplanes didn't have any sort of computer on board, Sure they had and often still have, it's called wetware. >so computation power is not the single deciding factor on the performance and success of such an endeavor The endeavor to charge a phone?
hnlmorg 3y ago
I don’t think you’re reading these articles in the right spirit if that’s your take away from them. What I find more interesting is to compare how complicated the tech we don’t think about has become. It’s amazing that a cable, not a smart device or even 80s digital watch, but a literal cable, has as much technology packed into it as Apollo 11 and we don’t even notice. Playing devils advocate for your comment, one of the (admittedly many) reasons going to the moon is harder than charging a USB device is because there are not off-the-shelf parts for space travel. If you had to build your USB charger from scratch (including defining the USB specification for the first time) each time you needed to charge your phone, I bet people would quickly talk about USB cables as a “hard problem” too. That is the biggest takeaway we should get from articles like this. Not that Apollo 11 wasn’t a hugely impressive feat of engineering. But that there is an enormous amount of engineering in our every day lives that is mass produced and we don’t even notice.
- argiopetech 3y ago
  This is actually about the wall warts the cable could be plugged into. Otherwise, I completely agree.

cubefox 3y ago

If anyone is interested, there is a 1965 documentary about an Apollo computer: https://youtube.com/watch?v=ndvmFlg1WmE https://youtube.com/watch?v=ndvmFlg1WmE

Havoc 3y ago

It has certainly felt like the limit is software/PEBKAC for a long while. Until lately with LLMs...that does make me feel "wish I had a bigger hammer" again.

denton-scratch 3y ago

> the LVDC actually contains triply-redundant logic I didn't know that was just for the LVDC. > emulate this voting scheme with 3x microcontrollers with a 4th to tally votes will not make the system any more reliable I think that's clear enough; the vote-tallier becomes a SPOF. I'm not sure how Tandem and Stratus handled discrepancies between their (twin) processors. Stratus used a pair of OTC 68K processors, which doesn't seem to mean voting; I can't see how you'd resolve a disagreement between just two voters. I can't see how you make a voting-based "reliable" processor from OTC CPU chips; I imagine it would require each CPU to observe the outputs of the other two, and tell itself to stop voting if it loses a ballot. Which sounds to me like custom CPU hardware. Any external hardware for comparing votes, telling a CPU to stop voting, and routing the vote-winning output, amounts to a vote-tallier, which is a SPOF. You could have three vote-talliers, checking up on one-another; but then you'd need a vote-tallier-tallier. It's turtles from then on down. In general, having multiple CPUs voting as a way of improving reliability seems fraught, because it increases complexity, which reduces reliability. Maybe making reliable processors amounts to just making processors that you can rely on.

ryukoposting 3y ago
> I can't see how you'd resolve a disagreement between just two voters. Tell them both to run the calculation again, perhaps?

simne 3y ago

> 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.

Rip_adam434 3y ago

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Rip_adam434 3y ago

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