A Practical Introduction to Input and Output Ports

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This chapter discusses how microprocessors interact with devices. It takes the student from the basics of input and output, through the design of the interface between a processor and an external device, and concludes with a discussion of how to improve the performance of the I/O interface using interrupts. The PC parallel port is examined to give the student a chance to apply these concepts in hardware and software. Once the student has studied the material of this chapter and completed the hands-on experiments, they will be prepared to begin a study of how device drivers work within the context of an operating system.