# Mechanical Computers, limits & possibilities **URL:** \ **Category:** Factual Questions\ **Created:** [March 21, 2018, 8:07pm UTC](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986 "2018-03-21T20:07:19Z")\ **Posts on this page:** 9\ **Page:** 3
**Author:** ![rbroome](https://avatars.discourse-cdn.com/v4/letter/r/838e76/32.png) [@rbroome](https://boards.straightdope.com/u/rbroome)\ **Post date:** [March 24, 2018, 1:58am UTC](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986/41 "2018-03-24T01:58:35Z")
> [@Dr.Strangelove](#): > > Hell, creating _any_ kind of wave that reliably goes up and down is pretty funny to anyone familiar with high speed signals. [PCIe Gen3, for instance](https://www.edn.com/electronics-blogs/practical-chip-design/4405647/PCIe-3-0-Equalization). pretty pictures! 🙂 ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [March 24, 2018, 2:03am UTC](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986/42 "2018-03-24T02:03:43Z")
> [@rbroome](#): > > pretty pictures! 🙂 Not so pretty to analog signal engineers! In diagrams like these, you want thin, tightly defined lines. Without heroics, though, you end up with a picture like the upper-right one–not just fat lines, but a homogeneous fuzzy blob. It’s astonishing that one can massage the signal to get _anything_ useful out of that. It’s black magic. ---
**Author:** ![dropzone](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dropzone/32/7515_2.png) [@dropzone](https://boards.straightdope.com/u/dropzone)\ **Post date:** [March 24, 2018, 3:35am UTC](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986/43 "2018-03-24T03:35:00Z")
> [@Stranger\_On\_A\_Train](#): > > [Not even close](https://history.nasa.gov/computers/Ch2-5.html). So what they are saying is that my TI-59 programmable calculator had more horsepower when I played Lunar Lander than the real thing had just twelve years earlier? ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [March 24, 2018, 7:58am UTC](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986/44 "2018-03-24T07:58:35Z")
> [@dropzone](#): > > So what they are saying is that my TI-59 programmable calculator had more horsepower when I played Lunar Lander than the real thing had just twelve years earlier? Actually, no. The real thing had a lot more memory, for one. Later TI calculators were faster but not this one. In addition, the Apollo stack had analog computers that aren’t in that calculator, and they were effectively performing operations that would be way too slow in the calculator. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [March 24, 2018, 12:57pm UTC](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986/45 "2018-03-24T12:57:08Z")
> [@Chronos](#): > > I’d actually argue that that’s more of a feature than a bug. Any calculation will only ever be as good as your inputs, and it’s quite rare for any of your inputs to actually be any better than three digits (because, of course, you’re usually reading it off of a device that has exactly the same sort of limitations as a slide rule). In that case, using an 8 or 12 digit electronic calculator doesn’t actually give you any increase in real precision; it only gives you the illusion of precision. Well, yeah. That’s why those things were more than adequate. In the days of mainframes, I worked in a plant where the engineers had a process model that would tell you to the nearest pound how much of the millions-plus of material was in process at any given time. This, despite, for example, material input via a feed belt weightometer with a 5% accuracy and a hiccup in the reading every time the staple in the belt went by. (Of course the engineers knew this - it was simpler to run with 8 digits than to account for tolerances in the model; they just made a “correction” based on inventory and estimates every 6 months). In fact I learned this when one of my jobs was to stop the belt, scoop off and weight 20 feet of feed, and compare reading to reality to fine-tune the model. But then a slide rule is a perfect example of your point. The world got by on 2.5 digits accuracy (or less) for a century or more. Also, a mechanical system like an old auto engine worked fairly well. OTOH, far more precise and adaptable computerized fuel injection and ignition has made a huge difference in performance, cleanliness, and efficiency to that same internal combustion engine… and this is the promise that computerized process control holds out for a huge number of processes - provided we can get past the 2-digit accuracy of many inputs. I should also mention the early process control device I helped with - where the X-squared variable was approximated with a linear calculation. As long as the process stayed within certain bounds, the approximation was “good enough”. ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [March 24, 2018, 3:34pm UTC](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986/46 "2018-03-24T15:34:39Z")
> [@dtilque](#): > > Slipstick Libby actually did all his calculations in his head; no slide rule used at all. You may remember the scene where the mechanical calculator broke down and he completed the asteroid’s manuever by doing the calculations that way. I can’t remember if it said so explicitly, but I expect that before the breakdown, he was crosschecking the calculator with his own calculations. You’re probably right; I remember the story but not the specifics. Probably conflating it with one of **Voyager** ’s slide rule covers. Wonder why they called him “Slipstick” then if he didn’t need one. > [@Dr.Strangelove](#): > > It’s astonishing that one can massage the signal to get _anything_ useful out of that. It’s black magic. Clarke’s Law in action. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 24, 2018, 4:39pm UTC](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986/47 "2018-03-24T16:39:26Z")
They didn’t call him “slipstick” because he used one; they called him that because he was one. He was a human calculator. ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [March 25, 2018, 2:48am UTC](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986/48 "2018-03-25T02:48:18Z")
It’s fun to make old mechanical calculators divide by zero. [![]( " - YouTube") ](https://www.youtube.com/watch?v=443B6f_4n6k) ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [March 25, 2018, 3:32am UTC](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986/49 "2018-03-25T03:32:19Z")
[quote=“Enola\_Straight, post:48, topic:810986”] It’s fun to make old mechanical calculators divide by zero. [/QUOTE] Ah, yes. In high school we had a Friden Comptometer (looking something like [this - top of page](http://www.oldcalculatormuseum.com/fridenstw.html) in our computer room, and making it divide by 0 was a lot of fun. We also had an early electronic calculator, an Olivetti Programma 101, but that just gave a boring error message. [Previous page](https://boards.straightdope.com/t/mechanical-computers-limits-possibilities/810986.md?page=2)