The solution is to allocate each program its own block of memory.

解决方案是为每个程序分配自己的内存块。

Let's take our example Program B, which has been allocated a block of memory from address 1000 to 1999.

让我们以我们的示例程序 B 为例，它已经分配了一块从地址 1000 到 1999 的内存。

We don't want to overwrite the neighboring one, so instead, the File System allocates an unused block, which can accommodate extra data.

我们不想覆盖相邻的，因此文件系统分配了一个未使用的块，可以容纳额外的数据。

In this way, we can have files of variable sizes that can be easily expanded and shrunk, simply by allocating and deallocating blocks.

通过这种方式，我们可以拥有可以轻松扩展和收缩的可变大小的文件，只需分配和释放块即可。

This too is invisible to Program A. As far as it can tell, it's been allocated a continuous block of 2000 addresses.

这对程序 A 来说也是不可见的。据它所知，它被分配了一个连续的 2000 个地址块。

This virtualization of memory addresses is even more useful for Program A, which in our example, has been allocated two blocks of memory that are separated from one another.

这种内存地址的虚拟化对于程序 A 更有用，在我们的示例中， 程序 A 已分配了两个彼此分开的内存块。