CMPEN 270 EXAM #2

Latch

Asynchronous - output changes as soon as the input changes

Choose the best answer: In digital design, the NMOS transistor (A) Behaves as a closed switch when Vgate = VDD. The switch conducts logic '0' (B) Behaves as a closed switch when Vgate = VDD. The switch conducts logic '1' (C) Behaves as an open switch when the Vgate = VDD. The switch conducts logic '1' (D) Behaves as a closed switch when Vgate = 0V. The switch conducts logic '0'

Behaves as a closed switch when Vgate = VDD. The switch conducts logic '0'

Choose the best answer: 32 bit IEEE 754 Floating point numbers (A) Store an exponent in 8 bits and magnitude in 23 bits (B) Have an exponent field which is represented in excess notation with a bias of 127 (C) Can be advantageous in storing very large and very small numbers (i.e. 1 atomic mass unit in kg or age of the earth (D) All of the above

All of the above

List two reasons why silicon is a commonly used semiconductor

Extreme Abundance Can be modified by doping

Which machine uses fewer states with more complex logics?

Mealy

Choose the best answer. Assuming the objective is to mark the center (bull's-eye), the picture represents what type of type of outcome (A) Accurate and precise (B) Not accurate, but precise (C) Accurate, but not precise (D) Neither precise nor accurate

Not accurate, but precise

Moore

output is a function of present state

Mealy

output is a function of present state and input

Choose the best answer: A PMOS transistor can be formed by first doping a pure crystal such that (A) a p-type semiconductor is produced (B) it becomes an intrinsic semiconductor (C) n-type source and drain regions are produced. The substrate is doped p-type. (D) p-type source and drain regions are produced. The substrate is doped n-type.

p-type source and drain regions are produced. The substrate is doped n-type

How many transistors in CMOS technology are used to build a: 2-Inverter feedback loop: 9 input NOR gate: 4 input AND gate: SR latch:

4 18 10 8

Explain the utility of the Output V

Output 'V' indicates if any of the input signals are active. The V output can be used to inform the CPU of the arrival of any interrupts.

Why do sequential circuits use feedback?

They use it because it reliably stores bits

How does feedback counteract normal direction of entropy?

It resists disorder (provides stability)

Name one example of a feedback system

Op Amp

Flip-Flop

Synchronous - output changes depending on control signals of high/low or low/high