Intel Microprocessor Interview Question:

Explain the 8279 operation?

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- The 8279 is basically a programmable keyboard and a component for display interfacing.

- The 8279 can scan and also encode a 64 key keyboard as well as a numerical display of 16 digits.

- The keyboard has a buffer based on FIFO to store up to 8 keys after which the processor must retrieve a character.

- It contains 8 lines that can be used to connect to 8 columns of a keyboard. There are two additional lines for STB keys.

- Once a key is pressed they are automatically debounced and it can function using two modes -key lockout and n-key roller.

- On simultaneous presses only the first key is detected. In case of n-key rollover mode all simultaneous presses are detected and stored in the internal buffer.
Submitted by: Administrator