51、Keyboard and Printer Interfacing: A Comprehensive Guide

Keyboard and Printer Interfacing: A Comprehensive Guide

1. Keyboard Types

There are two main types of keyboards: hard contact keyboards and capacitive keyboards. Capacitive keyboards are an alternative to hard contact keyboards. In capacitive keyboards, there is no physical contact between the rows and columns. Instead, there is a capacitor for each point of the matrix. When a key is pressed, the change in capacitance is detected by a sense amplifier, which produces a logic level indicating that a key has been pressed. Capacitive keyboards have a longer lifespan compared to hard contact keyboards. All IBM PC and PS machines, except the now - abandoned PC Jr. models, use capacitive keyboards.

Example: Checking Keyboard Buffer Status

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