# 53 bicycles: A lateral thinking puzzle **URL:** \ **Category:** Thread Games\ **Created:** [July 9, 2017, 7:51pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868 "2017-07-09T19:51:32Z")\ **Posts on this page:** 20\ **Page:** 124
**Author:** ![Knowed\_Out](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/knowed_out/32/7380_2.png) [@Knowed\_Out](https://boards.straightdope.com/u/Knowed_Out)\ **Post date:** [February 8, 2018, 1:19pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2461 "2018-02-08T13:19:43Z")
Sitting this one out for the techies. ---
**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:** [February 8, 2018, 2:14pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2462 "2018-02-08T14:14:13Z")
Is the technology applicable to optical storage? Is the technology applicable to magnetic storage? Is the technology applicable to some form of storage other than optical or magnetic? Did the idea come before 1970? Did the idea come in the 1970s? Did the idea come in the 1980s? Did the idea come in the 1990s? Did the idea come in the 2000s? Did the idea come in the 2010s? ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [February 8, 2018, 4:43pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2463 "2018-02-08T16:43:16Z")
> [@Chronos](#): > > Is the technology applicable to optical storage? > … > Did the idea come in the 1980s? Yes, _possibly_ applicable to optical storage, or some other storage types. The idea came in the late 1980’s. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [February 8, 2018, 5:01pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2464 "2018-02-08T17:01:11Z")
… My suggestion to run this odd puzzle was uncertain. But since we’ve started! 🙂 … Solution to this puzzle is in three parts: (1) Identify a slightly obvious approach for improving throughput from disk drives in a complex multi-tasking system. (2) Describe a policy (quite different from normal practice) which strongly affects (1). (3) [Optional] Explain why the combination of (1) and (2) may be beneficial. Asking you to go after _both_ (1) and (2) may be ridiculous. Perhaps I should describe (1) _OR_ (2) briefly and then ask you to work out the other. ---
**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:** [February 8, 2018, 5:26pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2465 "2018-02-08T17:26:45Z")
Does the idea involve holes? ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [February 8, 2018, 5:35pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2466 "2018-02-08T17:35:19Z")
Holes? No. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [February 8, 2018, 6:19pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2467 "2018-02-08T18:19:07Z")
> [@septimus](#): > > Solution to this puzzle is in three parts: > (1) Identify a slightly obvious approach for improving throughput from disk drives in a complex multi-tasking system. > (2) Describe a policy (quite different from normal practice) which strongly affects (1). > (3) [Optional] Explain why the combination of (1) and (2) may be beneficial. I’ll go ahead and discuss (1). Suppose disk is serving requests from multiple processes, some of which may be reading large sequential files in chunks. The operating system, or disk controller firmware, may guess or infer that a large sequential file is being read and do _speculative reads_ into an idle cache area, e.g. read all or part of Chunk N+1 after reading the Chunk N that was requested. Typically Chunk N+1 will follow Chunk N, so the disk was already poised to read it. The data which has been speculatively read may be presented immediately when it is eventually requested; improved throughput may result. (Even when the entire chunk N+1 is not pre-read, if the eventual seek to read Chunk N+1 lands in the middle of the buffered data one revolution is saved.) In the interesting case, the disk has another pending request; servicing that request (beginning with a seek) may be delayed if the _speculative read_(s) are done. Thus the speculative reads may do more harm than good. “Guessing” the proper amount of data to read speculatively poses problems. **Your mission is to determine (2) — the policy that interacts with (1) for alleged benefit.** ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [February 10, 2018, 7:12pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2468 "2018-02-10T19:12:05Z")
> [@septimus](#): > > **Your mission is to determine (2) — the policy that interacts with (1) for alleged benefit.** _ **Sorry for the thread hijack. I’ll withdraw and let someone else pose a puzzle.** _ (I was informed of this invention idea three decades ago — :eek: — and recall thinking “Aha!” and wondering whether someone could be guided toward this (clever?) invention idea via a series of leading questions. And somehow, so much later, it popped back into my head as a possibility for this thread. But it’s just too esoteric and specialized. Sorry.) To provide closure 😉 I’ll spoiler a hint at the invention … [SPOILER]… or rather, encode the partial solution using the [novel ciphering method I’ve introduced previously.](https://boards.straightdope.com/sdmb/showthread.php?p=20086300) alloycraFT AnDxX applAuDS aries begRutCh bicorNes bionAuts bUrneD counterFLow dOhMen LIlY moonpEnnY nakoNEM oFtEn oSWIs retrIevAL stegaLl tacahOUt tottyhEaD ucMHOU uNskin vieirA[/SPOILER] ---
**Author:** ![RadioWave](https://avatars.discourse-cdn.com/v4/letter/r/91b2a8/32.png) [@RadioWave](https://boards.straightdope.com/u/RadioWave)\ **Post date:** [February 10, 2018, 7:36pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2469 "2018-02-10T19:36:46Z")
Speaking as someone who’s done disk drive firmware for the past twenty years, you got me curious. There have been so many tricks like this, it would probably boggle your mind. It looks like pre-caching was the one you were aiming for but that’s been implemented many, many times, especially in streaming applications. Heck, I’ve implemented it myself 20 years ago. Is the second thing you’re asking about PRML (Partial Response, Most Likely)? Basically, the signals from the platter are coming in so fast there’s no time for the wires to form a nice clean signal so we take our best guess at whether it’s a zero or a one and then let error correction fix it. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [February 11, 2018, 12:16pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2470 "2018-02-11T12:16:38Z")
> [@RadioWave](#): > > Speaking as someone who’s done disk drive firmware for the past twenty years, you got me curious. There have been so many tricks like this, it would probably boggle your mind. > > It looks like pre-caching was the one you were aiming for but that’s been implemented many, many times, especially in streaming applications. Heck, I’ve implemented it myself 20 years ago. How does “pre-caching” differ from what I describe as (1) in #2466 ? The invention is something else, though it interacts with this. And why don’t you, with your experience, play the Yes/No game to guess the invention? :o It’s not too late — but if you decide to play, please open a new thread so we can stop the hijack here. (And maybe it’ll develop into a _Disk Experts vs Code Crackers_ contest if anyone tries to decipher my spoiler! 🙂 ) BTW, I was also involved in much disk controller firmware, though we have no overlap — the 30 years-ago anecdote was the _end_ of my involvement. (Admitting when my involvement _began_ would put to rest any lingering fantasy that I’m still in early middle-age. BTW, in the late 1950’s my brother’s godfather made a key innovation in the manufacture of magnetic read heads.) ---
**Author:** ![Biotop](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/biotop/32/321_2.png) [@Biotop](https://boards.straightdope.com/u/Biotop)\ **Post date:** [February 14, 2018, 5:11pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2471 "2018-02-14T17:11:32Z")
\*\*Winter Olympics themed question: “Bob” ( not his real name) wanted to win a medal for ice hockey, but he wanted to win it at the Summer Olympics. Bob, you would think, would be out of luck because while ice hockey began as a Summer Olympics sport in 1920, [it was moved permanently to the Winter Olympics in 1924.](https://en.wikipedia.org/wiki/Ice_hockey_at_the_Olympic_Games) The time for anyone winning medals for ice hockey in the summer games was over. Or so you might think. Though it was many years past 1924, Bob succeeded in his goal. How was this possible?\*\* ---
**Author:** ![Dead\_Cat](https://avatars.discourse-cdn.com/v4/letter/d/9fc29f/32.png) [@Dead\_Cat](https://boards.straightdope.com/u/Dead_Cat)\ **Post date:** [February 14, 2018, 6:03pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2472 "2018-02-14T18:03:05Z")
I’m not very good at these, but I’ll start. First of all, can you confirm if this restatement of the information given is correct: Bob has won a medal for Ice Hockey at a Summer Olympic games at some time after the year 1920. Did Bob win the medal by bidding highest in an auction? Did he win it in a bet? Did he “win” the medal in some sense other than being part of a team placed 1st, 2nd, or 3rd in the sport of ice hockey at the Olympics? If no, is the exact position (i.e. 1st/2nd/3rd) relevant or helpful to know in getting the solution? Is Bob human? Are there any clues in the article you linked to (which I haven’t read, yet)? ---
**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:** [February 14, 2018, 6:22pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2473 "2018-02-14T18:22:25Z")
Did Bob win his medal at some time in May, June, July, August, and/or September? Did Bob win his medal at a time when the noon sun is higher in the sky than average over the course of the year at that location? Did Bob win his medal at a time when the average temperatures are higher than the yearly average at that location? ---
**Author:** ![Biotop](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/biotop/32/321_2.png) [@Biotop](https://boards.straightdope.com/u/Biotop)\ **Post date:** [February 14, 2018, 6:23pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2474 "2018-02-14T18:23:52Z")
**reply to Dead Cat** I’m not very good at these, but I’ll start. First of all, can you confirm if this restatement of the information given is correct: Bob has won a medal for Ice Hockey at a Summer Olympic games at some time after the year 1920. **Yes** Did Bob win the medal by bidding highest in an auction? \*\* No.\*\* Did he win it in a bet? **No** Did he “win” the medal in some sense other than being part of a team placed 1st, 2nd, or 3rd in the sport of ice hockey at the Olympics? **Yes. (As noted, there was no ice hockey at the Summer Olympics after 1924)** If no, is the exact position (i.e. 1st/2nd/3rd) relevant or helpful to know in getting the solution? **N/A** Is Bob human? **Yes** Are there any clues in the article you linked to (which I haven’t read, yet)? **No** ---
**Author:** ![Thing\_Fish](https://avatars.discourse-cdn.com/v4/letter/t/ecb155/32.png) [@Thing\_Fish](https://boards.straightdope.com/u/Thing_Fish)\ **Post date:** [February 14, 2018, 6:28pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2475 "2018-02-14T18:28:07Z")
Does “Olympics” refer to the well known, quadrennial Olympic Games, as opposed to, for example, the Special Olympics or some other competition? ---
**Author:** ![Biotop](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/biotop/32/321_2.png) [@Biotop](https://boards.straightdope.com/u/Biotop)\ **Post date:** [February 14, 2018, 6:28pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2476 "2018-02-14T18:28:07Z")
\*\* reply to Chronos\*\* Did Bob win his medal at some time in May, June, July, August, and/or September? **Yes** Did Bob win his medal at a time when the noon sun is higher in the sky than average over the course of the year at that location? **Yes** Did Bob win his medal at a time when the average temperatures are higher than the yearly average at that location? **Yes** ---
**Author:** ![Thing\_Fish](https://avatars.discourse-cdn.com/v4/letter/t/ecb155/32.png) [@Thing\_Fish](https://boards.straightdope.com/u/Thing_Fish)\ **Post date:** [February 14, 2018, 6:30pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2477 "2018-02-14T18:30:03Z")
Was the medal, for some reason, formally awarded to Bob during the (post-1924) Summer Olympics, even though the competition in which he had earned it happened some time previous to that? ---
**Author:** ![Biotop](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/biotop/32/321_2.png) [@Biotop](https://boards.straightdope.com/u/Biotop)\ **Post date:** [February 14, 2018, 6:30pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2478 "2018-02-14T18:30:09Z")
**Answer to Thing Fish** Does “Olympics” refer to the well known, quadrennial Olympic Games, as opposed to, for example, the Special Olympics or some other competition? **Yes** ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [February 14, 2018, 6:32pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2479 "2018-02-14T18:32:47Z")
Was the medal awarded retroactively? ---
**Author:** ![Thing\_Fish](https://avatars.discourse-cdn.com/v4/letter/t/ecb155/32.png) [@Thing\_Fish](https://boards.straightdope.com/u/Thing_Fish)\ **Post date:** [February 14, 2018, 6:32pm UTC](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868/2480 "2018-02-14T18:32:48Z")
Wait a second…was the “goal” Bob succeeded at winning a medal in ice hockey at the Summer Olympics?:dubious: [Previous page](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868.md?page=123) [Next page](https://boards.straightdope.com/t/53-bicycles-a-lateral-thinking-puzzle/790868.md?page=125)