Digital Electronics and Microprocessors Flashcards

In a microprocessor-based avionics system, what is the primary function of the address bus?

Answer: To specify the memory location or I/O device being accessed

The address bus carries the binary address output by the CPU to select a specific memory location or I/O device.

Which logic gate produces a HIGH output only when all inputs are HIGH?

Answer: AND gate

An AND gate output is HIGH only when every input is simultaneously HIGH.

A D-type flip-flop in an avionics data register is clocked on the rising edge. What happens to the output Q when the clock transitions from LOW to HIGH?

Answer: Q takes on the value present at the D input at that moment

On the rising clock edge, a positive-edge-triggered D flip-flop captures and transfers the D input value to Q.

In ARINC 429 digital data bus, data words are transmitted:

Answer: Serially, one bit at a time on a differential pair

ARINC 429 uses serial transmission of 32-bit words over a shielded twisted-pair differential bus.

What does the term 'interrupt latency' refer to in an avionics microprocessor system?

Answer: The delay between an interrupt request and the CPU beginning its service routine

Interrupt latency is the elapsed time from when an interrupt is asserted until the CPU executes the first instruction of the interrupt service routine.

A 4-bit binary counter has a modulus of:

Answer: 16

A 4-bit counter can represent 2^4 = 16 unique states (0 through 15), giving it a modulus of 16.

Which Boolean expression correctly represents the output of an XNOR gate with inputs A and B?

Answer: NOT(A ⊕ B)

An XNOR gate is the complement of XOR, producing HIGH when inputs are equal: output = NOT(A ⊕ B).