2.4: Main Memory

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Memory can be viewed as a series of bytes, one after another. That is, memory is byte addressable. This means each memory address holds one byte of information. To store a double-word, four bytes are required which use four memory addresses.

Additionally, architecture is little-endian. This means that the Least Significant Byte (LSB) is stored in the lowest memory address. The Most Significant Byte (MSB) is stored in the highest memory location.

For a double-word (32-bits), the MSB and LSB are allocated as shown below.

截屏2021-07-18 下午3.45.11.png

For example, assuming the value of, 5,000,00010 (004C4B4016), is to be placed in a double-word variable named var1.

For a little-endian architecture, the memory picture would be as follows:

截屏2021-07-18 下午3.46.05.png

Based on the little-endian architecture, the LSB is stored in the lowest memory address and the MSB is stored in the highest memory location.