Определите основную идею текста
It was necessary that all personal computers were assembled from a kit.
A typical personal computer consists of a central processing unit, internal memory, external memory and various input/output devices.
Large-scale integration made it possible to construct a microprocessor on a single semiconductor chip.
First PCs of the 20th century designed to be used by individuals were being improved by different companies in terms of memory capacity, size and cost.