Difference between revisions of "Instruction"

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In more practical terms, the CPU operates by fetching items from [[main memory]]; each item contains a single directive for the CPU (e.g. a the contents of one [[register]] to another, or move a unit of data from a register, to main memory) - those items are instructions. (An instruction is usually a word, but on some CPUs, multiple instructions could be packed in each word, while on others, some instructions took multiple words.)
 
In more practical terms, the CPU operates by fetching items from [[main memory]]; each item contains a single directive for the CPU (e.g. a the contents of one [[register]] to another, or move a unit of data from a register, to main memory) - those items are instructions. (An instruction is usually a word, but on some CPUs, multiple instructions could be packed in each word, while on others, some instructions took multiple words.)
  
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Revision as of 14:21, 19 October 2018

An instruction is, at the highest level of abstraction, the smallest unit of computation which a programmer can direct the CPU to perform.

In more practical terms, the CPU operates by fetching items from main memory; each item contains a single directive for the CPU (e.g. a the contents of one register to another, or move a unit of data from a register, to main memory) - those items are instructions. (An instruction is usually a word, but on some CPUs, multiple instructions could be packed in each word, while on others, some instructions took multiple words.)