@glennparaiso
假设你有一群二十人在看有趣的蚱蜢，并试图记住每个人的样子。
该组还有一个（共享）数码相机，可用于拍摄蚱蜢的照片。
当人们记住每只蚱蜢的样子时，你会得到BRAM。
这是非常快的（它发生的速度就像你能看到和记住的那样快），并且没有拥塞（每个人都可以单独看到和记住蚱蜢）。
但是，每个人记忆的数量都有很低的限制。
即使能够完美地记住一只蚱蜢的形状/颜色也会令人印象深刻;
能做十到二十次会很棒。
DRAM是你用数码相机得到的。
它慢得多，一次只能有一个人使用它。
但是，你可以完美地“记住”数百只蚱蜢的形状/颜色。
数码相机的优点还在于，由于它是共享的，您可以向其他人展示您看到的蚱蜢。
您只需为作业选择正确的设备即可。
Block RAM具有高带宽和极低延迟，大多数芯片上都有数百个Block RAM（因此每个设计模块都可以使用一些）。
然而，它非常小 - 存储单个640x480彩色图像将使用比许多较小芯片可用的更多的块RAM。
片外RAM（DRAM）具有高带宽，但必须在所有块之间共享该带宽。
延迟很高，如果有太多的块试图立即访问RAM，则延迟可能非常高。
另一方面，找到一块装有1GB DDR3 RAM的电路板并不常见 - 足以容纳数千张图像。
由于DRAM是共享的，因此您可以轻松地使用它在块之间传输数据（这是在PL和PS之间获取数据的主要方式之一）。
以上来自于谷歌翻译
以下为原文
@glennparaiso
Suppose you've got a group of twenty people looking at interesting grasshoppers, and trying to remember the what each one looks like. The group also has a single (shared) digital camera that can be used to take photos of grasshoppers.
BRAM is what you get when people just remember what each grasshopper looks like. It's very fast (it happens as quickly as you can see and remember something), and there's no congestion (everyone can see and remember grasshoppers individually). However, there's a pretty low limit on how much each person can remember. Even being able to remember the shape/colour of one grasshopper perfectly would be impressive; being able to do ten or twenty would be amazing.
DRAM is what you get with the digital camera. It's much slower, and only one person can use it at a time. However, you can "remember" the shape/colour of hundreds of grasshoppers perfectly. The digital camera also has the advantage that, because it's shared, you can show everyone else what grasshoppers you saw.
You simply have to select the right device for the job.
Block RAM has high bandwidth and extremely low latency, and most chips have hundreds of block RAMs on them (so each design module can use a few). However, it's very small - storing a single 640x480 colour image will use more block RAMs than many of the smaller chips have available.
Off-chip RAM (DRAM) has high bandwidth, but that bandwidth has to be shared between all the blocks. Latency is high, and can be extremely high if too many blocks are trying to access the RAM at once. On the other hand, it's not at all unusual to find a board with 1GB of DDR3 RAM fitted - enough for thousands of images. Because the DRAM is shared, you can easily use it to transfer data between blocks (and this is one of the main ways of getting data between the PL and PS).
@glennparaiso
假设你有一群二十人在看有趣的蚱蜢，并试图记住每个人的样子。
该组还有一个（共享）数码相机，可用于拍摄蚱蜢的照片。
当人们记住每只蚱蜢的样子时，你会得到BRAM。
这是非常快的（它发生的速度就像你能看到和记住的那样快），并且没有拥塞（每个人都可以单独看到和记住蚱蜢）。
但是，每个人记忆的数量都有很低的限制。
即使能够完美地记住一只蚱蜢的形状/颜色也会令人印象深刻;
能做十到二十次会很棒。
DRAM是你用数码相机得到的。
它慢得多，一次只能有一个人使用它。
但是，你可以完美地“记住”数百只蚱蜢的形状/颜色。
数码相机的优点还在于，由于它是共享的，您可以向其他人展示您看到的蚱蜢。
您只需为作业选择正确的设备即可。
Block RAM具有高带宽和极低延迟，大多数芯片上都有数百个Block RAM（因此每个设计模块都可以使用一些）。
然而，它非常小 - 存储单个640x480彩色图像将使用比许多较小芯片可用的更多的块RAM。
片外RAM（DRAM）具有高带宽，但必须在所有块之间共享该带宽。
延迟很高，如果有太多的块试图立即访问RAM，则延迟可能非常高。
另一方面，找到一块装有1GB DDR3 RAM的电路板并不常见 - 足以容纳数千张图像。
由于DRAM是共享的，因此您可以轻松地使用它在块之间传输数据（这是在PL和PS之间获取数据的主要方式之一）。
以上来自于谷歌翻译
以下为原文
@glennparaiso
Suppose you've got a group of twenty people looking at interesting grasshoppers, and trying to remember the what each one looks like. The group also has a single (shared) digital camera that can be used to take photos of grasshoppers.
BRAM is what you get when people just remember what each grasshopper looks like. It's very fast (it happens as quickly as you can see and remember something), and there's no congestion (everyone can see and remember grasshoppers individually). However, there's a pretty low limit on how much each person can remember. Even being able to remember the shape/colour of one grasshopper perfectly would be impressive; being able to do ten or twenty would be amazing.
DRAM is what you get with the digital camera. It's much slower, and only one person can use it at a time. However, you can "remember" the shape/colour of hundreds of grasshoppers perfectly. The digital camera also has the advantage that, because it's shared, you can show everyone else what grasshoppers you saw.
You simply have to select the right device for the job.
Block RAM has high bandwidth and extremely low latency, and most chips have hundreds of block RAMs on them (so each design module can use a few). However, it's very small - storing a single 640x480 colour image will use more block RAMs than many of the smaller chips have available.
Off-chip RAM (DRAM) has high bandwidth, but that bandwidth has to be shared between all the blocks. Latency is high, and can be extremely high if too many blocks are trying to access the RAM at once. On the other hand, it's not at all unusual to find a board with 1GB of DDR3 RAM fitted - enough for thousands of images. Because the DRAM is shared, you can easily use it to transfer data between blocks (and this is one of the main ways of getting data between the PL and PS).
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