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640K Barrier Definition
DocumentID: 656128
Revision Date: 29-Feb-96 8:29:40 PM

The information in this document applies to:
WordPerfect® 5.1 for DOS

Problem

Solutions: 640K Barrier: The first-generation microcomputers utilizing the Intel 8088 or 8086 microprocessor chip were designed to address or manipulate 1,024 kilobytes of random access memory (RAM).

The designers figured that the lower 640 kilobytes of that 1,024K would be sufficient memory for DOS and its applications; so that's the way it was set-up. In the early to mid-1980's, when these systems began to proliferate, most of them operated with only 256K or 512K of memory (RAM), and the software applications then would execute with memory to spare.

By the late 1980's, systems were rarely sold with less than 640K of memory because the faster and more powerful programs had grown in size. They had reached the 640K barrier. Many interesting "work arounds" have been designed to extend and/or expand memory beyond the barrier.

Answer:

Details:


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