Although virtualization has, over the past few years, become one of the hottest topics in computing, it’s not a new idea. IBM, more than 50 years ago, had a virtual operating system that allowed a mainframe computer to run multiple copies of the same or different operating systems. Further, most operating systems support virtual memory, which, as shown in FIGURE 8-1, combines random access memory (RAM) and a page file on disk to create the illusion that a process (running program) has much more physical RAM than is present in the computer. Windows, Linux, macOS, and other operating systems all support virtual memory.
FIGURE 8-1 Virtual memory combines random access memory with a page file on disk to create the illusion of running programs on a vast amount of RAM.
