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Table Of Contents
Modern Computer Architecture and Organization - Third Edition
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The memory subsystem is an addressable sequence of storage locations containing instructions and data for the processor's use as it executes programs. Modern computer systems and digital devices often contain at least a billion 8-bit storage locations in main memory, each of which can be independently read from and written to by the processor.
As we saw in Chapter 1, Introducing Computer Architecture, the design of the Babbage Analytical Engine included a collection of axes, each holding 40 10-position wheels, to store data during computations. Reading data from an axis was a destructive operation, resulting in zero on the source axis's wheels when the read was complete. This was an entirely mechanical method of data storage.
From the 1950s to the 1970s, the preferred technology for digital computer memory was magnetic core memory. Each bit of core memory is stored in a small toroidal (donut-shaped) ceramic permanent magnet. The collection of cores that make...