并行傳輸數據和串行傳輸數據
SATA hard drive connections are faster than older PATA hard drive connections and the same can be said for external cabling standards, but this is counter-intuitive: why wouldn’t the parallel transmission be faster?
SATA硬盤驅動器的連接速度比舊的PATA硬盤驅動器連接要快，對于外部電纜連接標準也可以這么說，但這是違反直覺的：為什么并行傳輸不會更快？
Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites.
今天的“問答”環節由SuperUser提供，它是Stack Exchange的一個分支，該社區是由社區驅動的Q＆A網站分組。
問題 (The Question)
SuperUser reader Modest is curious about the data transfer rates of parallel and serial connections:
SuperUser閱讀器Modest對并行和串行連接的數據傳輸速率感到好奇：
Intuitively, you would think that parallel data transmission should be faster than serial data transmission; in parallel you are transferring many bits at the same time, whereas in serial you are doing one bit at a time.
憑直覺，您會認為并行數據傳輸應該比串行數據傳輸快； 并行操作是同時傳輸許多位，而串行操作是一次傳輸一位。
So what makes SATA interfaces faster than PATA, PCI-e devices faster than PCI, and serial ports faster than parallel?
那么，什么使SATA接口比PATA更快，PCI-e設備比PCI更快，串行端口比并行更快？
While it’s easy to fall into the reasoning that SATA is newer than PATA, there must be a more concrete mechanism at work than just age.
雖然很容易得出SATA比PATA更新的理由，但在工作中必須有一種比年齡更具體的機制。
答案 (The Answer)
SuperUser contributor Mpy offers some insight into the nature of the transmission types:
超級用戶貢獻者Mpy對傳輸類型的性質提供了一些見解：
You cannot formulate it this way.
您不能以此方式制定。
Serial transmission is?slower?than parallel transmission given the?same signal frequency.?With a parallel transmission you can transfer one word per cycle (e.g. 1 byte = 8 bits) but with a serial transmission only a fraction of it (e.g. 1 bit).
在相同的信號頻率下，串行傳輸比并行傳輸要慢。 在并行傳輸中，您可以每個周期傳輸一個字(例如1字節= 8位)，而在串行傳輸中，僅傳輸其一小部分(例如1位)。
The reason modern devices use serial transmission is the following:
現代設備使用串行傳輸的原因如下：
You cannot increase the signal frequency for a parallel transmission without limit, because, by design, all signals from the transmitter need to arrive at the receiver at?the same time. This cannot be guaranteed for high frequencies, as you cannot guarantee that the?signal transit time?is equal for all signal lines (think of different paths on the mainboard). The higher the frequency, the more tiny differences matter. Hence the receiver has to wait until all signal lines are settled — obviously, waiting lowers the transfer rate.
您可以在不增加信號頻率并行傳輸無極限，因為按照設計，從發射器需要的所有信號在接收器在同一時間到達。 這不能保證在高頻下使用，因為您不能保證所有信號線的信號傳輸時間都相等(請考慮主板上的不同路徑)。 頻率越高，差異越小。 因此，接收器必須等到所有信號線都建立好之后，顯然，等待會降低傳輸速率。
Another good point (from?this post) is that one needs to consider?crosstalk?with parallel signal lines. The higher the frequency, the more pronounced crosstalk gets and with it the higher the probability of a corrupted word and the need to retransmit it. [1]
另一個好處(來自本文)是，需要考慮與并行信號線的串擾。 頻率越高，串擾越明顯，隨之而來的單詞損壞和重傳的可能性也越高。 [1]
So, even if you transfer less data per cycle with a serial transmission, you can go to much higher frequencies which results in a higher net transfer rate.
因此，即使您使用串行傳輸每個周期傳輸較少的數據，您也可以使用更高的頻率，從而導致更高的凈傳輸速率。
[1] This also explains why?UDMA-Cables?(Parallel ATA with increased transfer speed) had twice as many wires as pins. Every second wire was grounded to reduce crosstalk.
[1]這也解釋了為什么UDMA電纜(具有更高傳輸速度的并行ATA)的導線數是引腳的兩倍。 每隔兩根導線接地，以減少串擾。
Scott Chamberlain echoes Myp’s answer and expands upon the economics of design:
斯科特·張伯倫(Scott Chamberlain)回應了Myp的回答，并擴展了設計經濟學：
The problem is synchronization.
問題是同步。
When you send in parallel you must measure all of the lines at the exact same moment, as you go faster the size of the window for that moment gets smaller and smaller, eventually it can get so small that some of the wires may still be stabilizing while others are finished before you ran out of time.
并行發送時，必須在同一時刻測量所有線路，因為隨著速度的加快，該時刻的窗口尺寸會越來越小，最終可能會變得很小，以至于某些電線可能仍在穩定而其他人則在您沒時間用完之前就完成了。
By sending in serial you no longer need to worry about all of the lines stabilizing, just one line. And it is more cost efficient to make one line stabilize 10 times faster than to add 10 lines at the same speed.
通過串行發送，您無需擔心所有線路都穩定下來，只需擔心一條線路。 而且，使一條線的穩定速度比以相同速度添加10條線的速度快10倍，具有更高的成本效益。
Some things like PCI Express do the best of both worlds, they do a parallel set of serial connections (the 16x port on your motherboard has 16 serial connections). By doing that each line does not need to be in perfect sync with the other lines, just as long as the controller at the other end can reorder the “packets” of data as they come in using the correct order.
諸如PCI Express之類的東西在兩全其美方面發揮了最大作用，它們完成了一組并行的串行連接(主板上的16x端口具有16個串行連接)。 通過這樣做，只要另一端的控制器可以按照正確的順序對數據的“數據包”進行重新排序，就不必與其他行完美同步。
The?How Stuff Works page for PCI-Express?does a very good explination in depth on how PCI Express in serial can be faster than PCI or PCI-X in parallel.
PCI-Express的“工作原理”頁面對串行PCI Express如何比并行PCI或PCI-X更快提供了很好的深度解釋。
TL;DR Version:?It is easier to make a single connection go 16 times faster than 8 connections go 2 times faster once you get to very high frequencies.
TL; DR版本：一旦到達非常高的頻率，使單個連接的傳輸速度比8個連接的傳輸速度快2倍就容易了。
Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users??Check out the full discussion thread here.
有什么補充說明嗎？ 在評論中聽起來不對。 是否想從其他精通Stack Exchange的用戶那里獲得更多答案？ 在此處查看完整的討論線程。
翻譯自: https://www.howtogeek.com/171947/why-is-serial-data-transmission-faster-than-parallel-data-transmission/
并行傳輸數據和串行傳輸數據
