This chapter describes interfacing characteristics of a microcomputer with typical peripheral devices such as a hexadecimal keyboard, display, DMA controller, printer, CRT (Cathode Ray tube) terminal, and coprocessor.

9.1    Keyboard Interface

9.1.1 Basics of Keyboard and Display Interface to a Microprocessor

A common method of entering programs into a microcomputer is via a keyboard. A popular way of displaying results by the microcomputer is by using seven segment displays. The main functions to be performed for interfacing a keyboard are

  • 1.  Sense a key actuation.
  • 2.  Debounce the key.
  • 3.  Decode the key.

Let us now elaborate on the keyboard interfacing concepts. A keyboard is arranged in rows and columns.

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