In Chapter 8, we discussed the ideas of interfacing a keyboard to the PC. It was seen that spe-
cialized microcontrollers are used to handle all the issues associated with keyboard interfacing.
As such, the main processor of the PC is free of the task of identifying the key pressed. How-
ever, still it is important to understand the mechanism of how a keypress is detected and how
the pressed key is identifi ed. For this purpose we use a hexadecimal keyboard, which has 16 keys
with the characters 0 to F. is keyboard is interfaced to the 8086 through the port lines of the
8255. ...
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