Digital Principles and System Design MCQs | Page - 15

 a multiplexer (or mux) is a device that selects one of several analog or digital input signals and forwards the selected input into a single line, depending on the active select lines. since many operational behaviour can be performed by using a multiplexer. whereas, a combinational circuit is a combination of many logic gates which makes the circuit more complex.

 a digital multiplexer is a combinational circuit that selects one digital information from several

 the selection of a particular input line is controlled by a set of selected lines in a multiplexer, which helps to select a particular input from several sources.

 if the number of n selected input lines is equal to 2^m then it requires m select lines to select one of m select lines.

 2n input lines, n control lines and 1 output line available for mux. here, 8 input lines mean 23 inputs. so, 3 control lines are possible.

 a basic multiplexer principle can be demonstrated through the use of a rotary switch. since its behaviour is similar to the multiplexer. there are

 the basic s-r flip-flop can be constructed by cross coupling of nor or nand gates. cross coupling means the output of second gate is fed to the input of first gate and vice-versa.

 the cross-coupled connections from the output of one gate to the input of the other gate constitute a feedback path. for this reason, the circuits of nor based s-r latch classified as asynchronous sequential circuits. moreover, they are referred to as asynchronous because they function in the absence of a clock pulse.

 the nand latch works when both inputs are 1. since, both of the inputs are inverted in a nand latch.

 the correct way to identify the positive edge of the clock signal is shown in option b. the ‘event attribute will detect the event and clk = ‘1’ will check whether its high on clock or not. in this way the positive edge is monitored. we need to use and operator because both of the conditions should be true.