(There are more, of course, but these three are the ones that were successful through a wide range of markets, which the and, for example, were not.) Despite all using the at their cores, there were few compatibilities between the systems. In particular, the advent of the and 16-bit s birthed three separate systems purpose-built with graphical capabilities in mind: the, the, and the. This state of affairs was established at the beginning of the mass personal computer market with the, and, and was accepted as something of a fact of life. Before about 1993, when the PC hardware standard finally took a commanding lead over its competitors, it was standard for different computer manufacturers to have completely different s, software bases, and communication methods. In the early days of computers, compatibility between systems was not as big an issue as it is today.
