Machine languageThe language made upof binary-coded instruc-tions that is used directlyby the computer7.3Machine Language189Where does the data that gets stored in the computer memory comefrom? How does the human ever get to see what is stored there, such asthe results of some calculation? There are other instructions that specifythe interaction between an input device and the CPU and between the CPUand an output device.7.2Levels of AbstractionWhen we described the problem-solving process in Chapter 6, we said thatan abstract step is one for which some details remain unspecified and aconcrete step is one for which the details are fully specified. How do weknow when a step is concrete? The answer depends on the programminglanguage in which we are going to express our algorithm.In our address example in Chapter 6, we assumed that the task or stepSort list on lastFirst fieldwas fully specified but that step Print the listwasnot. There are programming languages in which these assumptions are true.
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