Question

In the keypad application, the preset state of the ring counter define _____________

(a) The NANDing of the columns

(b) The NANDing of the rows

(c) The proper output of the column encoder

(d) The proper output of the row encoder

This question was addressed to me in an interview for internship.

Asked question is from Introduction to Hardware Description Language topic in chapter Memory Devices of Digital Circuits

Answer 1

Correct answer is (d) The proper output of the row encoder

The best I can explain: When a key is pressed the ring counter in the HDL scans the information provided by the user and counts to find the row. The preset state of the ring counter define the proper output of the row encoder.