Memory Barriers
Memory-mapped I/O is the cause of memory barriers in older generations of computers. The 640 KiB barrier is due to the IBM PC placing the Upper Memory Area in the 640–1024 KiB range (of its 20-bit memory addressing).
Read more about this topic: Memory-mapped I/O
Famous quotes containing the words memory and/or barriers:
“God gave us memory so that we might have roses in December.”
—J.M. (James Matthew)
“... so far from entrenching human conduct within the gentle barriers of peace and love, religion has ever been, and now is, the deepest source of contentions, wars, persecutions for conscience sake, angry words, angry feelings, backbitings, slanders, suspicions, false judgments, evil interpretations, unwise, unjust, injurious, inconsistent actions.”
—Frances Wright (1795–1852)