评论
打印
However, the typewriter had a further feature which was essential to its function. Its typing point could move, relative to the page.
然后，打字机要想工作，还有一个必须的特性，那就是它的打印头可以在纸上移动。
Its typing action would be independent of the position of this point on the page.
而它要打什么字，与它的打印头在什么位置是无关的。
Alan incorporated this idea too into his picture of the more general machine.
艾伦把这个想法，也推广到他设想的机器中。
It was to have internal 'configurations', and a variable position on a printing line.
这个机器有内部的状态，还有一个可以移动的打印头，
The action of the machine would not depend upon its position.
但它的动作与打印头的位置无关。
Neglecting details as to margins, line control, and so forth, these ideas would suffice to give a complete description of the nature of a typewriter.
如果忽略页边距和换行等细节，上面这些想法，就描述了打字机的本质。
An exact account of the configurations and positions allowed, and of how the character keys determined the symbols printed, the shift key the change of configuration from 'lower' to 'upper', and the space bar and backspace the printing position, would bring out the features most relevant to its function.
状态和允许的位置，键盘如何确定打印的字符，换档键切换大小写，还有空格和退格。
If an engineer took this account, and created a physical machine which met its specifications, the result would be a typewriter, regardless of its colour, weight, or other attributes.
一个工程师只要知道这些，并且造出一台相应的机器，无论是什么颜色、什么重量，它就是一台打字机。
But a typewriter was too limited to serve as a model.
但是，用打字机作为模型，太有局限性了。
It dealt with symbols, but it could only write them, and it required a human operator to choose the symbols and changes of configuration and position, one at a time.
虽然它能处理符号，但它只是把符号印出来，而且它还需要人类操作者来逐个选择符号，改变大小写和位置。
What, Alan Turing asked, would be the most general kind of machine that dealt with symbols?
艾伦·图灵便问，那么什么样的符号机器才是普适的呢？
To be a 'machine' it would have to retain the typewriter's quality of having a finite number of configurations, and an exactly determined behaviour in each.
作为机器，它要保留打字机的有限状态和确定行为。
But it would have to be capable of much more.
但只有这些是不够的，它还要有些别的。
And so he imagined machines which were, in effect, super-typewriters.
艾伦设想的机器，相当于一台超级打字机。
To simplify the description he imagined his machines working with just one line of writing. This was only a technicality, which allowed margins and line control to be forgotten.
为了简化，他忽略了页边距和换行这样的技术问题，设想这台机器只在一行上工作。
But it was important that the supply of paper was to be assumed unlimited.
但重要的是，他设想纸带的长度是无限的。
In his picture, the typing point of his super-typewriter could progress indefinitely to left or right.
在他的描述中，他的超级打字机，可以无限地在纸带上向左或向右移动。
For the sake of definiteness, he imagined the paper as being in the form of a tape, marked off into unit squares, such that just one symbol could be written on any one square.
为了清晰，他设想纸带划分成方格子，每个方格只能写一个符号。
Thus his machines were to be finitely defined, but they would be allowed an unlimited amount of space on which to work.
这样，他的机器是有限定义的，但却拥有无限的空间来工作。
