It starts working and loads a program so it's ready to be used.

它开始工作并加载程序，这样就可以使用了。

This operating system not only loaded programs automatically, like earlier batch systems, but could also run several at the same time on its single CPU. It did this through clever scheduling.

这个操作系统不仅像早期的批处理系统一样自动加载程序，而且还可以在其单个 CPU 上同时运行多个程序。它通过巧妙的调度来做到这一点。