There was a further fundamental consideration besides that of discreteness, reliability and speed: that of sheer size.
除了离散、可靠和速度之外，还有一些基本问题需要考虑。
There would have to be room on the 'tape' of a universal machine both for the 'description numbers' of the machines it had to imitate, and its workings.
通用机的纸带，必须有足够的空间来容纳机器要执行的描述数，已及供它运行的工作空间。
The abstract universal machine of 1936 was equipped with a 'tape' of infinite length, meaning that although at any stage the amount of tape used would be finite, it was assumed that as more space was required it could always be made available.
在1936年，抽象的通用机配置了无限长的纸带，这意味着，虽然在任意时刻机器使用的纸带长度总是有限的，但他假想了机器总是能够满足任何空间需求。
In a practical machine, space would always be limited in extent—and for that reason no physical machine could actually realise a truly universal machine.
但是在实际的机器上，空间总是有限的，因此，没有一台实际的机器可以成为真正的通用机。
Still, Alan had suggested in Computable Numbers that human memory was finite in extent.
艾伦还在《可计算数》中表明，人脑的记忆容量也是有限的，
If this were so then the human brain itself could hold only a limited number of 'tables of behaviour', and a sufficiently large tape could contain them all.
倘若如此，那么人脑就只能记住有限数量的行为表，而且这些可以放进一个足够长的纸带。
The finiteness of any practical machine would not, on this argument, debar it from having a brain-like quality.
从这个论点出发，实际机器的纸带是否有限，并不影响它具有人脑的功能。
The question was, however, how much 'tape' would be required for a machine that could actually be built: enough to make it interesting, but not more than would be technically feasible.
但问题是，实际建造一个机器，到底需要多长的纸带？纸带的长度要使机器具有足够的能力，但又不能超越技术可行性。
And how could such storage be arranged without inconceivable expense in terms of electronic valves?
还有，怎样安排这些存储，才能尽量避免使用过多的电子管？