Linux® on the Mainframe

2.2. General-purpose computer architecture

Around 1960, there were many computer systems in the marketplace, each developed for a specific purpose. Some were optimized, for example, to do accounting, others to solve engineering problems or to help scientists with complex calculations. At the time, about 80% of the total customer cost of the IT environment was spent on hardware. Therefore, fully exploiting the capabilities of a piece of hardware was crucial for an efficient IT operation.

To efficiently use IT resources, it was sometimes desirable to move a program between computers. This was not easy. Figure 2-2 illustrates the relationship between the hardware, or electronic layer, and the program, application, or user layer at that time. To ...