In many ways, our memories make us who we are, helping us remember our past,
在许多方面，记忆决定了我们是什么样的人，让我们不要忘记过去，
learn and retain skills, and plan for the future.
学习和记住新技能，为未来做计划。
And for the computers that often act as extensions of ourselves, memory plays much the same role,
例如，计算机经常扮演人类延伸的角色，内存也起着同样的作用，
whether it's a two-hour movie, a two-word text file, or the instructions for opening either,
无论是一部两个小时的电影，写两个单词的文本，还是执行打开两者的指令，
everything in a computer's memory takes the form of basic units called bits, or binary digits.
计算机内存中的一切都以基本单位比特的形式出现，我们也称之为二进制数字。
Each of these is stored in a memory cell that can switch between two states for two possible values, 0 and 1.
存储元件中存储着每个二进制数，在两个可能值之间自由转换：0和1。
Files and programs consist of millions of these bits,
由数百万计的二进制数组成的程序和文件
all processed in the central processing unit, or CPU, that acts as the computer's brain.
统一处理中央处理器，即CPU，它是计算机大脑的职位。
And as the number of bits needing to be processed grows exponentially,
而且，随着要处理的二进制数量成倍增加，
computer designers face a constant struggle between size, cost, and speed.
计算机设计师不断面临数据规模、成本和处理速度三个问题。
Like us, computers have short-term memory for immediate tasks, and long-term memory for more permanent storage.
和我们一样，计算机对即时任务有短期记忆，并且有更长的固定存储器来保留长期记忆。
When you run a program, your operating system allocates area within the short-term memory for performing those instructions.
当您操作程序时，操作系统位于短期记忆区域，以执行指令。
For example, when you press a key in a word processor,
例如，当您在文本处理软件中按下一个键时，
the CPU will access one of these locations to retrieve bits of data.
中央处理器访问其中一个位置来检索数据。
It could also modify them, or create new ones.
它还可以修改或生成新数据。
The time this takes is known as the memory's latency.
这一过程所花费的时间称为延迟。
And because program instructions must be processed quickly and continuously,
由于程序指令必须快速、持续地处理，
all locations within the short-term memory can be accessed in any order, hence the name random access memory.
短期记忆区的所有定位点都是按任何顺序访问的，因此也被称为随机访问存储器。
The most common type of RAM is dynamic RAM, or DRAM.
最常见的随机存储器是动态随机存储器，或者DRAM。
There, each memory cell consists of a tiny transistor and a capacitor that store electrical charges,
a 0 when there's no charge, or a 1 when charged.
0代表没有电，有电代表1。
Such memory is called dynamic because it only holds charges briefly before they leak away,
动态记忆之所以被称为动态记忆，是因为它只是在电荷耗散前短时间保留它们，
requiring periodic recharging to retain data.
这些数据需要定期充电。
But even its low latency of 100 nanoseconds is too long for modern CPUs,
但即使是100纳秒的低延迟，对现代来说也是如此CPU都算是高延迟，
so there's also a small, high-speed internal memory cache made from static RAM.
因此，内部快记忆体应运而生，即静态随机存取存储器。
That's usually made up of six interlocked transistors which don't need refreshing.
它通常由六个联结晶状体组成，不需要更新。
SRAM is the fastest memory in a computer system, but also the most expensive,
静态随机存取存储器是计算机系统中最快的存储器，但也是最昂贵的，
and takes up three times more space than DRAM.
它还占用了比动态随机访问存储器多三倍的空间。
But RAM and cache can only hold data as long as they're powered.
但是RAM高速缓冲存储器只有在充电后才能保存数据。
For data to remain once the device is turned off,
为保留数据，一旦设备关闭，
it must be transferred into a long-term storage device, which comes in three major types.
有三种类型的存储设备必须转移到长期存储设备中。
In magnetic storage, which is the cheapest,
磁存储器，即三者中最便宜的存储设备，
data is stored as a magnetic pattern on a spinning disc coated with magnetic film.
磁膜编码的旋转盘上存储数据。
But because the disc must rotate to where the data is located in order to be read,
但由于圆盘必须转移到数据位置才能读取，
the latency for such drives is 100,000 times slower than that of DRAM.
因此，磁储存器的延迟比DRAM慢上100000倍。
On the other hand, optical-based storage like DVD and Blu-ray also uses spinning discs, but with a reflective coating.
另一方面，像DVD和蓝牙这样的光储存设备同样也使用旋转盘，只不过多了一层反射涂层。
Bits are encoded as light and dark spots using a dye that can be read by a laser.
二进制数字被编译成空白点和黑点，用于激光识别和读取涂层。
While optial storage media are cheap and removable,
尽管光储存媒体价钱便宜并可摘除，
they have even slower latencies than magnetic storage and lower capacity as well.
它们甚至比磁存储器有着更低的延时，同样也有着更小的容量。
Finally, the newest and fastest types of long-term storage are solid-state drives, like flash sticks.
最后，固态硬盘是最新也是最快捷的长期存储器，比如闪存存储器。
These have no moving parts, instead using floating gate transistors
它没有可运转的部件，而是使用浮栅晶体管，
that store bits by trapping or removing electrical charges within their specially designed internal structures.
在他人专门设计的内部构件中以捕获和排除电荷存储二进制数字。
So how reliable are these billions of bits?
那么，这数十亿的二进制数字可靠性到底如何？
We tend to think of computer memory as stable and permanent, but it actually degrades fairly quickly.
我们总认为计算机存储器具有稳定性和永久性，但实际上它降解得相当快。
The heat generated from a device and its environment will eventually demagnetize hard drives,
由装置和周身环境所产生的热会使硬盘去磁，
degrade the dye in optical media, and cause charge leakage in floating gates.
降解光学媒体内的染料，并造成浮置栅极里的电荷流失。
Solid-state drives also have an additional weakness.
固态硬盘也有额外的缺陷。
Repeatedly writing to floating gate transistors corrodes them, eventually rendering them useless.
在不断重复存盘到浮栅中的过程中，晶体管会腐蚀固态硬盘，使之毫无用处。
With data on most current storage media having less than a ten-year life expectancy,
当今大多存储媒体内的数据寿命预测也不超过10年，
scientists are working to exploit the physical properties of materials down to the quantum level
科学家们正在尝试开拓材料的物理性能将它们降至量子水平，
in the hopes of making memory devices faster, smaller, and more durable.
希望能因此制造出更快、更小以及更耐久的设备。
For now, immortality remains out of reach, for humans and computers alike.
眼下，不朽仍无法实现，不论对于人类还是电脑而言都是这样。