As CPUs improved, memory-handling capabilities have improved as well. Today’s microprocessors, such as the
Intel Pentium or Pentium Pro, are capable of addressing more than GB of system memory—well beyond the levels of contemporary software applications. Unfortunately, the early PCs were not nearly so powerful. Older PCs could only address MB of memory because of the limitations of the 8088 microprocessor. Because backward compatibility is
so important to computer users, the drawbacks and limitations of older systems had to be carried forward into newer computers, instead of being eliminated. Newer systems overcome their inherent limitations by adding
different types of memory, along with the hardware and software to access the memory. This part of the chapter describes the typical classifications of computer memory conventional,
extended, and expanded memory. This chapter also describes high memory concepts. Notice that these memory types have nothing to do with the actual ICs in your system, but the way in which software uses the memory.
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