Revolution brought a new scale to human civilization# Early Computing

Early Computing: Crash Course Computer Science #1

英文

Hello world, I’m Carrie Anne, and welcome to CrashCourse Computer Science!

Over the course of this series, we’re going to go from bits, bytes, transistors and logic gates, all the way to Operating Systems, Virtual Reality and Robots!

We’re going to cover a lot, but just to clear things up - we ARE NOT going to teach you how to program.

Instead, we’re going to explore a range of computing topics as a discipline and a technology.

Computers are the lifeblood of today’s world.

If they were to suddenly turn off, all at once, the power grid would shut down, cars would crash, planes would fall, water treatment plants would stop, stock markets would trucks with food wouldn’t know where to deliver, and employees wouldn’t get paid.

Even many non-computer objects - like DFTBA shirts and the chair I’m sitting on – are made in factories run by computers.

Computing really has transformed nearly every aspect of our lives.

And this isn’t the first time we’ve seen this sort of technology-driven global change.

Advances in manufacturing during the IndustrialRevolution brought a new scale to human civilization - in agriculture, industry and domestic life.

Mechanization meant superior harvests and more food, mass produced goods, cheaper and faster travel and communication, and usually a better quality of life.

And computing technology is doing the same right now – from automated farming and medical equipment, to global telecommunications and educational opportunities, and new frontiers like Virtual Reality and Self Driving Cars.

We are living in a time likely to be remembered as the Electronic Age.

With billions of transistors in just your smartphones, computers can seem pretty complicated, but really, they’re just simple machines that perform complex actions through many layers of abstraction.

So in this series, we’re going break down those layers, and build up from simple 1’s and 0’s, to logic units, CPUs, operating systems, the entire internet and beyond.

And don’t worry, in the same way someone buying t-shirts on a webpage doesn’t need to know how that webpage was programmed, or the web designer doesn’t need to know how all the packets are routed, or router engineers don’t need to know about transistor logic, this series will build on previous episodes but not be dependent on them.

By the end of this series, I hope that you can better contextualize computing’s role both in your own life and society, and how humanity's (arguably) greatest invention is just in its infancy, with its biggest impacts yet to come.

But before we get into all that, we should start at computing’s origins, because although electronic computers are relatively new, the need for computation is not.

The earliest recognized device for computing was the abacus, invented in Mesopotamia around 2500 BCE.

It’s essentially a hand operated calculator, that helps add and subtract many numbers.

It also stores the current state of the computation, much like your hard drive does today.

The abacus was created because, the scale of society had become greater than what a single person could keep and manipulate in their mind.

There might be thousands of people in a village or tens of thousands of cattle.

There are many variants of the abacus, but let’s look at a really basic version with each row representing a different power of ten.

So each bead on the bottom row represents a single unit, in the next row they represent 10, the row above 100, and so on.

Let’s say we have 3 heads of cattle represented by 3 beads on the bottom row on the right side. If we were to buy 4 more cattle we would just slide 4 more beads to the right for a total of 7.

But if we were to add 5 more after the first 3 we would run out of beads, so we would slide everything back to the left, slide one bead on the second row to the right, representing ten, and then add the final 2 beads on the bottom row for a total of 12.

This is particularly useful with large numbers.

So if we were to add 1,251 we would just add 1 to the bottom row, 5 to the second row, 2 to the third row, and 1 to the fourth row - we don’t have to add in our head and the abacus stores the total for us.

Over the next 4000 years, humans developed all sorts of clever computing devices, like the astrolabe, which enabled ships to calculate their latitude at sea.

Or the slide rule, for assisting with multiplication and division.

And there are literally hundred of types of clocks created that could be used to calculate sunrise, tides, positions of celestial bodies, and even just the time.

Each one of these devices made something that was previously laborious to calculate much faster, easier, and often more accurate –– it lowered the barrier to entry, and at the same time, amplified our mental abilities –– take note, this is a theme we’re going to touch on a lot in this series.

As early computer pioneer Charles Babbage said: “At each increase of knowledge, as well as on the contrivance of every new tool, human labour becomes abridged.”

However, none of these devices were called “computers”.

The earliest documented use of the word “computer” is from 1613, in a book by Richard Braithwait.

And it wasn’t a machine at all - it was a job title.

Braithwait said, “I have read the truest computer of times, and the best arithmetician that ever breathed, and he reduceth thy dayes into a short number”.

In those days, computer was a person who did calculations, sometimes with the help of machines, but often not.

This job title persisted until the late 1800s, when the meaning of computer started shifting to refer to devices.

Notable among these devices was the Step Reckoner, built by German polymath Gottfried Leibniz in 1694.

Leibniz said “... it is beneath the dignity of excellent men to waste their time in calculation when any peasant could do the work just as accurately with the aid of a machine.”

It worked kind of like the odometer in your car, which is really just a machine for adding up the number of miles your car has driven.

The device had a series of gears that turned; each gear had ten teeth, to represent the digits from 0 to 9.

Whenever a gear bypassed nine, it rotated back to 0 and advanced the adjacent gear by one tooth.

Kind of like when hitting 10 on that basic abacus.

This worked in reverse when doing subtraction, too.

With some clever mechanical tricks, the Step Reckoner was also able to multiply and divide numbers.

Multiplications and divisions are really just many additions and subtractions.

For example, if we want to divide 17 by 5, we just subtract 5, then 5, then 5 again, and then we can’t subtract any more 5’s… so we know 5 goes into 17 three times, with 2 left over.

The Step Reckoner was able to do this in an automated way, and was the first machine that could do all four of these operations.

And this design was so successful it was used for the next three centuries of calculator design.

Unfortunately, even with mechanical calculators, most real world problems required many steps of computation before an answer was determined.

It could take hours or days to generate a single result.

Also, these hand-crafted machines were expensive, and not accessible to most of the population.

So, before 20th century, most people experienced computing through pre-computed tables assembled by those amazing “human computers” we talked about.

So if you needed to know the square root of 8 million 6 hundred and 75 thousand 3 hundred and 9, instead of spending all day hand-cranking your step reckoner, you could look it up in a huge book full of square root tables in a minute or so.

Speed and accuracy is particularly important on the battlefield, and so militaries were among the first to apply computing to complex problems.

A particularly difficult problem is accurately firing artillery shells, which by the 1800s could travel well over a kilometer (or a bit more than half a mile).

Add to this varying wind conditions, temperature, and atmospheric pressure, and even hitting something as large as a ship was difficult.

Range Tables were created that allowed gunners to look up environmental conditions and the distance they wanted to fire, and the table would tell them the angle to set the canon.

These Range Tables worked so well, they were used well into World War Two.

The problem was, if you changed the design of the cannon or of the shell, a whole new table had to be computed, which was massively time consuming and inevitably led to errors.

Charles Babbage acknowledged this problem in 1822 in a paper to the Royal Astronomical

Society entitled: “Note on the application of machinery to the computation of astronomical and mathematical tables"

Let’s go to the thought bubble.

Charles Babbage proposed a new mechanical device called the Difference Engine, a much more complex machine that could approximate polynomials.

Polynomials describe the relationship between several variables - like range and air pressure, or amount of pizza Carrie Anne eats and happiness.

Polynomials could also be used to approximate logarithmic and trigonometric functions, which

are a real hassle to calculate by hand.

Babbage started construction in 1823, and over the next two decades, tried to fabricate and assemble the 25,000 components, collectively weighing around 15 tons.

Unfortunately, the project was ultimately abandoned.

But, in 1991, historians finished constructing a Difference Engine based on Babbage's drawings and writings - and it worked!

But more importantly, during construction of the Difference Engine, Babbage imagined an even more complex machine - the Analytical Engine.

Unlike the Difference Engine, Step Reckoner and all other computational devices before it - the Analytical Engine was a “general purpose computer”.

It could be used for many things, not just one particular computation; it could be given data and run operations in sequence; it had memory and even a primitive printer.

Like the Difference Engine, it was ahead of its time, and was never fully constructed.

However, the idea of an “automatic computer” – one that could guide itself through a series of operations automatically, was a huge deal, and would foreshadow computer programs.

English mathematician Ada Lovelace wrote hypothetical programs for the Analytical Engine, saying, “A new, a vast, and a powerful language is developed for the future use of analysis.”

For her work, Ada is often considered the world’s first programmer.

The Analytical Engine would inspire, arguably, the first generation of computer scientists, who incorporated many of Babbage’s ideas in their machines.

This is why Babbage is often considered the "father of computing".

Thanks Thought Bubble!

So by the end of the 19th century, computing devices were used for special purpose tasks in the sciences and engineering, but rarely seen in business, government or domestic life.

However, the US government faced a serious problem for its 1890 census that demanded the kind of efficiency that only computers could provide.

The US Constitution requires that a census be conducted every ten years, for the purposes of distributing federal funds, representation in congress, and good stuff like that.

And by 1880, the US population was booming, mostly due to immigration.

That census took seven years to manually compile and by the time it was completed, it was already out of date – and it was predicted that the 1890 census would take 13 years to compute.

That’s a little problematic when it’s required every decade!

The Census bureau turned to Herman Hollerith, who had built a tabulating machine.

His machine was “electro-mechanical” – it used traditional mechanical systems for keeping count, like Leibniz’s Step Reckoner –– but coupled them with electrically-powered components.

Hollerith’s machine used punch cards which were paper cards with a grid of locations that can be punched out to represent data.

For example, there was a series of holes for marital status.

If you were married, you would punch out the married spot, then when the card was inserted into Hollerith’s machine, little metal pins would come down over the card – if a spot was punched out, the pin would pass through the hole in the paper and into a little vial of mercury, which completed the circuit.

This now completed circuit powered an electric motor, which turned a gear to add one, in this case, to the “married” total.

Hollerith’s machine was roughly 10x faster than manual tabulations, and the Census was completed in just two and a half years - saving the census office millions of dollars.

Businesses began recognizing the value of computing, and saw its potential to boost profits by improving labor- and data-intensive tasks, like accounting, insurance appraisals, and inventory management.

To meet this demand, Hollerith founded The Tabulating Machine Company, which later merged with other machine makers in 1924 to become The International Business Machines Corporation or IBM - which you’ve probably heard of.

These electro-mechanical “business machines” were a huge success, transforming commerce and government, and by the mid-1900s, the explosion in world population and the rise of globalized trade demanded even faster and more flexible tools for processing data, setting the stage for digital computers, which we’ll talk about next week.

中文

Hello world; 我是Carrie Anne,欢迎收看Crash Course:Computer Science!

在这个系列中,我们会了解bits,bytes,晶体管与逻辑门

一直到操作系统,虚拟现实与机器人

我们会了解很多东西,但是先解释一下 我们不会教你如何编程

相反,我们会以一项学科和技术的角度纵览一系列计算机话题

计算机是当今世界的命脉

如果现在关闭所有的计算机 输电网会关闭,车辆会撞在一起,飞机会坠毁 水处理厂会关闭,证券市场会停止运作,载满食物的卡车不知要运向何方,雇员们也会得不到薪水,甚至许多跟计算机没有关系的食物,例如DFTBA的T恤和我正在坐的椅子,它们也是在被计算机运作的工厂中制造的

计算机已经几乎改变了我们生活中的方方面面

这也不是我们第一次看到这种“改变全局”的科技了

工业革命中生产能力的提高,提升了人们在农业,工业,以及畜牧业中的规模

机械化代表着优越的收成,更多的食物,和大规模生产的货物

更加便宜和快速的旅行和通讯,和通常更好的生活品质

计算机这种科技如今也做着同样的事情 从自动化农业和医疗设备,到全球的电子通信和教育机会,以及虚拟现实和自动驾驶汽车等新领域

我们生活在一个会被叫做“信息时代”的时代

如果只看你手机中那数十亿晶体管的话,计算机可能看起来会相当复杂

但是讲真,它们只是通过许多层的抽象结构

表现复杂行为的简单机器

因此在这个系列中,我们会剥开那些复杂的抽象层

从底层用“1”和“0”来构建逻辑门,CPU 操作系统,整个互联网,等等

不用担心嘛,同样来说, 在网页上买T恤的人并不需要知道

网页是如何编写的 网页设计师也并不需要知道

所有数据是如何被分组路由的 研发路由器的工程师并不需要了解晶体管的逻辑

这个系列将建立在以前的剧集的基础上, 但并不依赖于它们

在这个系列的末尾 我希望你能更好地了解计算机

在生活和社会中所扮演的角色 以及人类最伟大的发明（大概是这样）

是如何刚刚起步的 其最大的影响可尚未到来

但在我们了解这一切之前,我们应该从计算的起源讲起

虽然电子计算机是比较新出现的,但人类对于计算的需要并不是

最早被认可的计算设备是算盘 大约公元前2500年发明于美索不达米亚

它本质上是一个手动计算器 用来帮助人们加减数字

它还存储当前的计算状态,类似于如今的硬盘做的事

人们制造算盘是因为社会的规模已经比

个人可以在脑中储存和操作的规模更大

一个村庄可能有成千上万的人或数以万计的牛

算盘有许多的变种,但让我们来看看一个基本的版本

其每一行代表着10的不同次方

因此每个底部的珠子表示一个基本单位（10 ^ 0）

旁边那行便是10（10 ^ 1）,在旁边那行表示100（10 ^ 2）,以此类推

我们说移至右侧的三颗底部珠子表示3头牛

如果我们要再买4头牛,我们只用向右滑动4颗珠子,总共7个

但如果我们之后再添加5个,我们就会用完珠子

所以我们将所有的东西移回左边 将第二排的一个珠子向右移动来代表10 然后在底行加上最后2个珠字,总共12个

然后在底行加上最后2个珠字,总共12个

所以如果我们要加1251 我们只是在底行加1,第二行加5,第三行加2,第四行加1

我们不必在脑子里做加减,算盘会为我们储存结果

在接下来的4000年种,人类开发了各种聪明的计算设备

例如星盘,可以使船只在海上计算其纬度

或者计算尺,用于辅助乘法和除法

人们创造了上百种时钟 它们可以用来计算

日出,潮汐,天体的位置,或者只是计算时间

这些设备使之前费力的运算计算得更加

快速, 更加简便和精确 这降低了计算的门槛

同时也加强了我们处理信息的能力 记笔记,这是一个我们会在这个系列中会讨论很多次的主题

早期计算机先驱Charles Babbage曾说： “每当人类知识增长创造新工具时 人工劳动力会得到衰减”,然而,这些设备那时都不叫“计算机”

最早的记载“计算机”一词的文献来自1613年Richard Braithwait发表的一本书,而且这并不是指一种机器,而是一种职业

Braithwait写到： “我见到最精确的计算者是那时世上最好的算术家, 他能将长久之时化作简洁之数”

那时,"Computer"一词是指一个做计算的人 "Computer"们有时会有机器的帮助,但大部分时间里并不会有

这个职位持续到19世纪末 在那时"Computer"之意开始转向了机器

在这些机器中,莱布尼茨乘法器格外著名 它由德国博学家戈特弗里德·莱布尼茨于1694年建造,莱布尼茨曾说:"...让卓越的人浪费时间在计算上是在侮辱他们的尊严特别是当一个农夫在机器的帮助下都能算得同样准确时”

这个机器的工作方式类似你车中的里程表它只是个不断累加你的车走过的里程数的机器

这个设备有一系列转动的齿轮 每个齿轮有十个齿,表示从0到9的数字每当一个齿轮转过9时,它便会旋转回到0并使相邻的齿轮前进1个齿,类似于当算盘敲到10时,做减法时机器会相反方向工作

利用一些机智的机械技巧,莱布尼茨乘法器,也能够乘数和除数乘法和除法实际上只是许多加法和减法的累积

举个例子,如果我们要将17除以5,我们只要减5,然后再减5,再减5,这时我们就不能再减5了,所以我们知道17 = 2x5 +2

莱布尼茨乘法器可以自动实现这种操作,而且它也是第一台能做到加减乘除四种运算的机器

这个设计是如此成功以至于它被用于未来三个世纪的计算器设计,不幸的是,即使使用了机械计算器,许多现实问题仍需要许多步骤来确定

这样生成单个结果可能需要几个小时或几天

此外,这些手工制作的机器十分昂贵,大多数人承担不起

所以,在20世纪之前 大多数人通过预先计算的计算表来计算

这些计算表便由那些之前谈论的“人力计算器”编撰

所以如果你想知道8676309的平方根

除了手摇一整天你的莱布尼茨乘法器之外 你还可以花一分钟左右

在一张装满平方根的大表里查找答案

速度和准确性在战场上尤为重要

因此军队便是首先将计算应用于复杂问题的先驱之一,如何准确地射击炮弹是一个特别困难的问题 19世纪,这些炮弹的射程可以达到一公里以上（比一英里多一点）,加上风力条件,温度和大气压力的变化,即使要打中像一艘船一样大的东西也是非常困难的

人们便制作了射程表来让炮手通过查询环境条件,和他们希望炮弹飞过的距离 这张表便会告诉他们需要设置的角度

这些射程表工作得很好,它们被很好地用于第二次世界大战

问题是,如果你改变了大炮或炮弹的设计

人们就得计算一张全新的表,这样做非常耗时并且会不可避免地导致错误

Charles Babbage在1822年 向皇家天文学会的一篇论文中承认这个问题,论文名叫:“机械在天文与计算表中的应用”

让我们来进入脑洞世界

Charles Babbage提出了一种称为差分机的新型机械装置,这是一个可以近似多项式的更加复杂的机器

多项式描述了几个变量之间的关系 例如射程和大气压力

或者Carrie Anne要吃多少披萨才会开心

多项式也可以用于近似对数和三角函数

这些函数手算相当麻烦

Charles Babbage于1823年开始建造差分机

并在接下来的二十年里,试图制造和组装25000个零件 这些零件总重接近15吨

不幸的是,该项目最终被放弃了,然而,在1991年 历史学家根据Charles Babbage的草稿

建成了一个差分机 而且它能正常使用！

但更重要的是,在差分机的建造期间 Charles Babbage想象了一个更复杂的机器 - 分析机

不像差分机 以及莱布尼茨乘法器和所有其他以前的计算设备,-分析机是一台“通用计算机”,它可以用于许多事情,并不只是一个特定的计算

它可以按顺序给出数据并运行操作 它有内存甚至一个原始的打印机

像差分机一样,这台机器太超前了,并没有完全建成

然而,这种“自动计算机”的概念 -这种计算机可以通过一系列操作自动引导自身

这是个跨时代的概念,它会预示计算机程序的产生

英国数学家Ada Lovelace为差分机编写了假想程序,这被称作“这是一门为未来分析之用的一个全新的庞大的强有效的语言”

因为她的成果,Ada经常被认为是世界上第一位程序员

分析机将会激励（可以这么讲）第一代计算机科学家

这些计算机科学家们将许多Charles Babbage的想法纳入他们的机器

这就是为什么Charles Babbage经常被认为是“计算之父”

感谢Thought Bubble！

所以到了19世纪末 计算设备被用于

科学和工程领域中的特殊目的性任务,但它们在商业,政府和家庭生活中很少见到

然而,美国政府在其1890年的人口普查中面临一个严重的问题

这种问题需要只有计算机可以提供的那种效率

美国宪法要求每十年进行一次人口普查,这是为了分配联邦资金,国会代表,以及类似的东西

到了1880年,美国人口因移民而迅速增长,这项人口普查需要七年时间进行手工编制

到它完成的时候,它已经过时了,而且预计1890年的人口普查需要13年的时间来手工计算

当普查每十年进行一次时便会出现问题

人口普查局找到了Herman Hollerith,他发明了打孔卡片制表机

他的机器是“电动机械的” - 它使用传统的机械系统来计数

它的计数结构类似莱布尼茨的乘法器,但它使用电动结构连接其他组件

Hollerith的机器使用打孔卡,这是一种带有网格并用打孔来表示数据的纸卡

举个例子,这有一系列表示婚姻状况的孔,如果你结婚了,你会在“结婚”的位置打孔

然后当卡插入Hollerith的机器时,小金属针会经过整张卡片-如果一个点被打孔,针会穿过纸上的孔

并进入一小瓶汞,并联通电路,这个已联通的电路由电动机驱动

在这种情况下,它变成了一个齿轮,给“已婚”总数加一Hollerith机器的速度大约是手动制表的10倍

并且人口普查在短短两年半内便完成了 - 这为人口普查办公室节省了数百万美元

各个企业开始认识到计算的价值并发现了通过改进劳动力和数据密集型任务,从而提高利润的潜力,例如在会计,保险评估和库存管理等行业中

为了满足这一需求,Hollerith成立了制表机器公司

这家公司后来于1924年与其它机械制造商合并 成为了国际商业机器股份有限公司（IBM）-这你可能听说过,这些电子机械的“商业机器”取得了巨大的成功,改变了商业和政府,到了20世纪中叶,世界人口的爆炸和全球化贸易的兴起,要求更快,更灵活的工具来处理数据

这为电子计算机的发展奠定了基础,关于这个话题我们会在下周讨论