Modern computers are revolutionizing our lives, performing tasks unimaginable only decades ago.
现代计算机正在改变着我们的生活，处理着几十年前人们无法想象的事情。
This was made possible by a long series of innovations,
一连串的创新实现了那些人们在十几年前无法完成的事情，
but there's one foundational invention that almost everything else relies upon: the transistor.
但几乎所有的技术都取决于一个划时代性的发明：晶体管。
So what is that, and how does such a device enable all the amazing things computers can do?
所以，什么是晶体管，这是一个什么样的东西可以让计算机完成那么多神奇的事情？
Well, at their core, all computers are just what the name implies, machines that perform mathematical operations.
顾名思义，计算机就是一个进行数学运算的机械。
The earliest computers were manual counting devices, like the abacus, while later ones used mechanical parts.
最初的计算机是人手动运行计算的，比如算盘，后来计算机里增加了机械部件。
What made them computers was having a way to represent numbers and a system for manipulating them.
计算机的特点便是用特定方式表示数字，并运用系统处理数字。
Electronic computers work the same way,
电子计算机使用同机械计算机相同的运算方式，
but instead of physical arrangements, the numbers are represented by electric voltages.
但电子计算机不使用物理排列数字，而被电压代替。
Most such computers use a type of math called Boolean logic that has only two possible values,
大部分的计算机使用布尔数学体系，它只有两种可能的值，
the logical conditions true and false, denoted by binary digits one and zero.
那就是正确和错误的逻辑条件，并用二进制数值1和0表示。
They are represented by high and low voltages.
它们被高和低电压表述着。
Equations are implemented via logic gate circuits
程式通过逻辑门电路来执行，
that produce an output of one or zero based on whether the inputs satisfy a certain logical statement.
并输出1或0，基于输入值是否符合某一个逻辑陈述。
These circuits perform three fundamental logical operations, conjunction, disjunction, and negation.
这些电路处理三种基本的逻辑运算：合取、析取与取反。
The way conjunction works is an 'and gate' provides a high-voltage output only if it receives two high-voltage inputs,
合取类似于“且”运算，当它接受到两个高电压输入时，产生高电压输出。
and the other gates work by similar principles.
其他两种逻辑运算工作原理相似。
Circuits can be combined to perform complex operations, like addition and subtraction.
电路可以通过结合来处理复杂的运算，比如加法和减法。
And computer programs consist of instructions for electronically performing these operations.
计算机程序由执行这些操作的电子指令组成。
This kind of system needs a reliable and accurate method for controlling electric current.
这种系统需要一个可靠且精准的算法来控制电流。
Early electronic computers, like the ENIAC, used a device called the vacuum tube.
早期电子计算机，比如电子数值积分计算机，使用了一种叫真空管的设备。
Its early form, the diode, consisted of two electrodes in an evacuated glass container.
真空管是二极管的前身，在一个真空玻璃管内放置两个电极。
Applying a voltage to the cathode makes it heat up and release electrons.
通过给阴极电压并使温度上升来释放电子。
If the anode is at a slightly higher positive potential, the electrons are attracted to it, completing the circuit.
如果阳极处在一个高一点的正电位，电子就会被吸引过去，联通电路。

This unidirectional current flow could be controlled by varying the voltage to the cathode, which makes it release more or less electrons.
这种单方向电流是可控的，通过对阴极使用不同的电压，可以使阴极释放不同数量的电子。
The next stage was the triode, which uses a third electrode called the grid.
下一个是三极管，使用了第三个电极叫做栅极。
This is a wire screen between the cathode and anode through which electrons could pass.
这是一种在阴极与阳极之间的网格状的线路，并可以使电子通过。
Varying its voltage makes it either repel or attract the electrons emitted by the cathode, thus, enabling fast current-switching.
不同的电压可以使它排斥或者吸引阴极发出的电子，从而，得以实现快速电流开关。
The ability to amplify signals also made the triode crucial for radio and long distance communication.
三极管可以放大信号的性能使它成为收音机的关键部位，还有长距通信。
But despite these advancements, vacuum tubes were unreliable and bulky.
虽然真空管有这些优点，它不稳定且体型笨重。
With 18,000 triodes, ENIAC was nearly the size of a tennis court and weighed 30 tons.
电子数值积分计算机使用了18000个真空管，这使它的体积近似于一个网球场并重达30吨。
Tubes failed every other day, and in one hour, it consumed the amount of electricity used by 15 homes in a day.
几乎每天都有真空管出现故障，而且使用它1小时的电量等同于15个家庭的日用电量。
The solution was the transistor.
问题的解决办法是晶体管。
Instead of electrodes, it uses a semiconductor,
它使用了半导体来替代电极，
like silicon treated with different elements to create an electron-emitting N-type, and an electron absorbing P-type.
比如用其它元素处理过的硅来制造一个电子发射N型和一个电子接收P型。
These are arranged in three alternating layers with a terminal at each.
这些被排列在三个交替层，并在每一层有一个终端。
The emitter, the base, and the collector.
发射极，基极和接收极。
In this typical NPN transistor, due to certain phenomena at the P-N interface,
在典型的NPN晶体管，由于有些出现在在P-N接口的现象，
a special region called a P-N junction forms between the emitter and base.
一个在发射极和基极之间的特别的区域叫做P-N结。
It only conducts electricity when a voltage exceeding a certain threshold is applied.
当电压超过某一阀值时，它才会导电。
Otherwise, it remains switched off.
不然，它会处于关闭状态。
In this way, small variations in the input voltage can be used to quickly switch between high and low-output currents.
以这种方式，输入电压里的小变化可以激发高低输出电流之间的转换。
The advantage of the transistor lies in its efficiency and compactness.
晶体管的优点在于它的高效和小体积。
Because they don't require heating, they're more durable and use less power.
因为晶体管不需要加热，它们更加的耐用与低耗。
ENIAC's functionality can now be surpassed by a single fingernail-sized microchip containing billions of transistors.
现在，电子数值积分计算机的性能已被携带着几十亿个晶体管的指甲盖大小的微芯片所超越。
At trillions of calculations per second, today's computers may seem like they're performing miracles,
有着每秒万亿次计算的当代计算机看上去是在展现着一个奇迹，
but underneath it all, each individual operation is still as simple as the flick of a switch.
但是在它背后，每一个运算仍然只是一个简单的开关动作。