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Lesson Summary

The following points summarize the main elements of this lesson:

• Hexadecimal notation is used as shorthand for writing binary numbers.
• Memory is defined in terms of the physical characteristics of the chips and how the memory is allocated for use.
• The MS-DOS operating system can address only the first 1 MB of memory.
• Expanded memory was an early method of adding memory to an MS-DOS-based system. It paged, or swapped, 64-KB chunks of data through a window (a 64-KB block of memory in the upper memory area) to an expansion card.
• Extended memory, used by Windows 3.x and newer systems, allows the addressing of memory above the MS-DOS limit and has virtually replaced expanded memory.
• Understanding memory allocation and the different memory locations is key to optimizing a computer's memory.
• The MS-DOS command MEM.COM is a utility that provides information about memory allocation.

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