In this chapter we narrow our scope from the system-level speculations of Chapter 1 to the nuts-and-volts hardware level. This is more than a formality. It is impossible to write effective software for a real-time system without an understanding of the system’s hardware, because the hardware and the software are too strongly related. The hardware scans all the relevant available states of the environment, encodes them, and reports them to the software; the software responds to the reports, part of the response being to output encoded instructions to the hardware. The job of the software is to decode the inputs into meaningful information, determine the appropriate reaction, and encode the reaction into output signals. All of this decoding and encoding is heavily dependent on the nature of the hardware with which the software is communicating.
KeywordsClock Signal Assembly Language Program Counter Index Register Code Segment
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