McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Computer Science Engineering (CSE) , Electronics and Telecommunication Engineering [ENTC] .
| 251. |
When is a level-shifter circuit needed in interfacing logic? |
| A. | a level shifter is always needed. |
| B. | a level shifter is never needed. |
| C. | when the supply voltages are the same |
| D. | when the supply voltages are different |
| Answer» D. when the supply voltages are different | |
| 252. |
A TTL totem-pole circuit is designed so that the output transistors: |
| A. | are always on together |
| B. | provide linear phase splitting |
| C. | provide voltage regulation |
| D. | are never on together |
| Answer» D. are never on together | |
| 253. |
The most common TTL series ICs are: |
| A. | e-mosfet |
| B. | 7400 |
| C. | quad |
| D. | ac00 |
| Answer» B. 7400 | |
| 254. |
Which family of devices has the characteristic of preventing saturation during operation? |
| A. | ttl |
| B. | ecl |
| C. | mos |
| D. | iil |
| Answer» B. ecl | |
| 255. |
How many 74LSTTL logic gates can be driven from a 74TTL gate? |
| A. | 10 |
| B. | 20 |
| C. | 30 |
| D. | 40 |
| Answer» B. 20 | |
| 256. |
What is the difference between the 74HC00 series and the 74HCT00 series of CMOS logic? |
| A. | the hct series is faster. |
| B. | the hct series is slower. |
| C. | he hct series is input and output voltage compatible with ttl. |
| D. | the hct series is not input and output voltage compatible with ttl. |
| Answer» C. he hct series is input and output voltage compatible with ttl. | |
| 257. |
Why are the maximum value of VOL and the minimum value of VOH used to determine the noise margin rather than the typical values for these parameters? |
| A. | these are worst-case conditions. |
| B. | these are normal conditions. |
| C. | these are best-case conditions. |
| D. | it doesn\t matter what values are used. |
| Answer» A. these are worst-case conditions. | |
| 258. |
What is the standard TTL noise margin? |
| A. | 5.0 v |
| B. | 0.0 v |
| C. | 0.8 v |
| D. | 0.4 v |
| Answer» D. 0.4 v | |
| 259. |
Which logic family is characterized by a multiemitter transistor on the input? |
| A. | ecl |
| B. | cmos |
| C. | ttl |
| D. | none of the above |
| Answer» C. ttl | |
| 260. |
he problem of the VOH(min) of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of VIH(min) is usually easily overcome by: |
| A. | adding a fixed voltage- divider bias resistive network at the output of the ttl device |
| B. | avoiding this condition and only using ttl to drive ttl |
| C. | adding an external pull- down resistor to ground |
| D. | adding an external pull-up resistor to vcc |
| Answer» D. adding an external pull-up resistor to vcc | |
| 261. |
How does the 4000 series of CMOS logic compare in terms of speed and power dissipation to the standard family of TTL logic? |
| A. | more power dissipation and slower speed |
| B. | more power dissipation and faster speed |
| C. | less power dissipation and faster speed |
| D. | less power dissipation and slower speed |
| Answer» D. less power dissipation and slower speed | |
| 262. |
What should be done with unused inputs to a TTL NAND gate? |
| A. | let them float |
| B. | tie them low |
| C. | tie them high |
| D. | none of the above |
| Answer» C. tie them high | |
| 263. |
Which of the following logic families has the highest maximum clock frequency? |
| A. | s-ttl |
| B. | as-ttl |
| C. | hs-ttl |
| D. | hcmos |
| Answer» B. as-ttl | |
| 264. |
Why is the fan-out of CMOS gates frequency dependent? |
| A. | each cmos input gate has a specific propagation time and this limits the number of different gates that can be connected to the output of a cmos gate. |
| B. | when the frequency reaches the critical value, the gate will only be capable of delivering 70% of the normal output voltage and consequently the output power will be one-half of normal; this defines the upper operating frequency. |
| C. | the higher the number of gates attached to the output, the more frequently they will have to be serviced, thus reducing the frequency at which each will be serviced with an input signal. |
| D. | the input gates of the fets are predomina ntly capacitive, and as the signal frequency increases the capacitive loading also increases, thereby limiting the number of loads that may be attached to the output of the driving gate. |
| Answer» D. the input gates of the fets are predomina ntly capacitive, and as the signal frequency increases the capacitive loading also increases, thereby limiting the number of loads that may be attached to the output of the driving gate. | |
| 265. |
What must be done to interface TTL to CMOS? |
| A. | a dropping resistor must be used on the cmos 12 v supply to reduce it to 5 v for the ttl. |
| B. | as long as the cmos supply voltage is 5 v, they can be interfaced; however, the fan-out of the ttl is limited to five cmos gates. |
| C. | a 5 v zener diode must be placed across the inputs of the ttl gates in order to protect them from the higher output voltages of the cmos gates. |
| D. | a pull-up resistor must be used between the ttl output- cmos input node and vcc; the value of rp will depend on the number of cmos gates connected to the node. |
| Answer» D. a pull-up resistor must be used between the ttl output- cmos input node and vcc; the value of rp will depend on the number of cmos gates connected to the node. | |
| 266. |
What causes low-power Schottky TTL to use less power than the 74XX series TTL? |
| A. | the schottky- clamped transistor |
| B. | nothing. the 74xx series uses less power. |
| C. | a larger value resistor |
| D. | using nand gates |
| Answer» C. a larger value resistor | |
| 267. |
What are the major differences between the 5400 and 7400 series of ICs? |
| A. | the 5400 series are military grade and require tighter supply voltages and temperatures. |
| B. | the 5400 series are military grade and allow for a wider range of supply voltages and temperature s. |
| C. | the 7400 series are an improvement over the original 5400s. |
| D. | the 7400 series was originally developed by texas instrumen ts. the 5400 series was brought out by national semicondu ctors after ti\s patents expired, as a second supply source. |
| Answer» B. the 5400 series are military grade and allow for a wider range of supply voltages and temperature s. | |
| 268. |
Which of the following statements apply to CMOS devices? |
| A. | the devices should not be inserted into circuits with the power on. |
| B. | all tools, test equipment, and metal workbenches should be tied to earth ground. |
| C. | the devices should be stored and shipped in antistatic tubes or conductive foam. |
| D. | all of the above. |
| Answer» D. all of the above. | |
| 269. |
Which of the logic families listed below allows the highest operating frequency? |
| A. | 74as |
| B. | ecl |
| C. | hcmos |
| D. | 54s |
| Answer» B. ecl | |
| 270. |
What is the increase in switching speed between 74LS series TTL and 74HC/HCT (High-Speed CMOS)? |
| A. | 5 |
| B. | 10 |
| C. | 50 |
| D. | 100 |
| Answer» B. 10 | |
| 271. |
What does ECL stand for? |
| A. | electron- coupled logic; |
| B. | emitter- coupled logic; |
| C. | energy- coupled logic; |
| D. | none of above |
| Answer» B. emitter- coupled logic; | |
| 272. |
What is unique about TTL devices such as the 74S00? |
| A. | the gate transistors are silicon (s), and the gates therefore have lower values of leakage current. |
| B. | the s denotes the fact that a single gate is present in the ic rather than the usual package of 2–6 gates. |
| C. | the s denotes a slow version of the device, which is a consequence of its higher power rating. |
| D. | the devices use schottky transistors and diodes to prevent them from going into saturation; this results in faster turn on and turn off times, which translates into higher frequency operation. |
| Answer» D. the devices use schottky transistors and diodes to prevent them from going into saturation; this results in faster turn on and turn off times, which translates into higher frequency operation. | |
| 273. |
he bipolar TTL logic family that was developed to increase switching speed by preventing transistor saturation is: |
| A. | emitter- coupled logic (ecl). |
| B. | current- mode logic (cml). |
| C. | transistor- transistor logic (ttl). |
| D. | emitter- coupled logic (ecl) and transistor- transistor logic (ttl). |
| Answer» D. emitter- coupled logic (ecl) and transistor- transistor logic (ttl). | |
| 274. |
In TTL the noise margin is between |
| A. | 0.4 v and 0.8 v. |
| B. | 0.0 v and 0.4 v. |
| C. | 0.0 v and 0.5 v. |
| D. | 0.0v and 0.8 v. |
| Answer» A. 0.4 v and 0.8 v. | |
| 275. |
What is the transitive voltage for the voltage input of a CMOS operating from 10V supply |
| A. | 1v |
| B. | 5v |
| C. | 10v |
| D. | 15v |
| Answer» B. 5v | |
| 276. |
The highest noise margin is offered by |
| A. | cmos |
| B. | ttl |
| C. | ecl |
| D. | bicmos |
| Answer» B. ttl | |
| 277. |
What is the transitive voltage for the voltage input of a CMOS operating from 10V supply ? |
| A. | 1v |
| B. | 5v |
| C. | 10v |
| D. | 20v |
| Answer» B. 5v | |
| 278. |
Which of the following logic families is well suited for high-speed operations ? |
| A. | ttl |
| B. | ecl |
| C. | mos |
| D. | cmos |
| Answer» B. ecl | |
| 279. |
Which of the following is the fastest logic? |
| A. | ecl |
| B. | ttl |
| C. | mos |
| D. | cmos |
| Answer» A. ecl | |
| 280. |
he digital logic family which has the lowest propagation delay time is |
| A. | ecl |
| B. | ttl |
| C. | cmos |
| D. | pmos |
| Answer» C. cmos | |
| 281. |
Which of the following statements is wrong ? |
| A. | propagation delay is the time required for a gate to change its state |
| B. | noise immunity is the amount of noise which can be applied to the input of a gate without causing the gate to change state |
| C. | fan-in of a gate is always equal to fan-out of the same gate |
| D. | operating speed is the maximum frequency at which digital data can be applied to a gate |
| Answer» C. fan-in of a gate is always equal to fan-out of the same gate | |
| 282. |
Which table shows the logical state of a digital circuit output for every possible combination of logical states in the inputs ? |
| A. | function table |
| B. | truth table |
| C. | routing table |
| D. | ascii table |
| Answer» B. truth table | |
| 283. |
The digital logic family which has minimum power dissipation is |
| A. | ttl |
| B. | ecl |
| C. | mos |
| D. | cmos |
| Answer» D. cmos | |
| 284. |
In the following question, match each of the items A, B and C on the left with an approximation item on the right
|
| A. | a b c 1 2 3 |
| B. | a b c 3 4 1 |
| C. | a b c 5 4 2 |
| D. | a b c 1 3 5 |
| Answer» B. a b c 3 4 1 | |
| 285. |
A standard SOP form has terms that have all the variables in the domain of the expression. |
| A. | sum |
| B. | sub |
| C. | mult |
| D. | div |
| Answer» A. sum | |
| 286. |
How many data select lines are required for selecting eight inputs? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» C. 3 | |
| 287. |
Half adder circuit is ? |
| A. | half of an and gate |
| B. | a circuit to add two bits together |
| C. | half of a nand gate |
| D. | none of above |
| Answer» B. a circuit to add two bits together | |
| 288. |
The full adder adds the Kth bits of two numbers to the |
| A. | difference of the previous bits |
| B. | sum of all previous bits |
| C. | carry from ( k - 1 )th bit |
| D. | sum of previous bit |
| Answer» C. carry from ( k - 1 )th bit | |
| 289. |
The number of two input multiplexers required to construct a 210 input multiplexer is, |
| A. | 31 |
| B. | 10 |
| C. | 127 |
| D. | 1023 |
| Answer» D. 1023 | |
| 290. |
A small dot or circle printed on top of an IC indicates |
| A. | vcc |
| B. | gnd |
| C. | pin 14 |
| D. | pin 1 |
| Answer» D. pin 1 | |
| 291. |
Which of the following adders can add three or more numbers at a time ? |
| A. | parallel adder |
| B. | carry-look- ahead adder |
| C. | carry-save- adder d. |
| D. | full adder |
| Answer» B. carry-look- ahead adder | |
| 292. |
An AND circuit |
| A. | is a memory circuit |
| B. | gives an output when all input signals are present simultaneous ly |
| C. | is a -ve or gate |
| D. | is a linear circuit |
| Answer» B. gives an output when all input signals are present simultaneous ly | |
| 293. |
What are the three output conditions of a three-state buffer? |
| A. | high, low, float |
| B. | 1, 0, float |
| C. | both of the above |
| D. | neither of the above |
| Answer» C. both of the above | |
| 294. |
The device which changes from serial data to parallel data is |
| A. | counter |
| B. | multiplexe r |
| C. | demultiple xer |
| D. | flip-flop |
| Answer» C. demultiple xer | |
| 295. |
A device which converts BCD to Seven Segment is called |
| A. | multiplexer |
| B. | demultipl exer |
| C. | encoder |
| D. | decoder |
| Answer» D. decoder | |
| 296. |
How many 3-line-to-8-line decoders are required for a 1-of-32 decoder? |
| A. | 1 |
| B. | 2 |
| C. | 4 |
| D. | 8 |
| Answer» C. 4 | |
| 297. |
A device which converts BCD to Seven Segment is called |
| A. | encoder |
| B. | decoder |
| C. | multiplexer |
| D. | demultiple xer |
| Answer» B. decoder | |
| 298. |
A multiplexer is a logic circuit that |
| A. | accepts one input and gives several output |
| B. | accepts many inputs and gives many output |
| C. | accepts many inputs and gives one output |
| D. | accepts one input and gives one output |
| Answer» C. accepts many inputs and gives one output | |
| 299. |
In order to implement a n variable switching function, a MUX must have |
| A. | 2n inputs |
| B. | 2n+1 inputs |
| C. | 2n-1 inputs |
| D. | 2n-1 inputs |
| Answer» A. 2n inputs | |
| 300. |
A latch is constructed using two cross-coupled |
| A. | and and or gates |
| B. | and gates |
| C. | nand and nor gates |
| D. | nand gates |
| Answer» D. nand gates | |
Done Studing? Take A Test.
Great job completing your study session! Now it's time to put your knowledge to the test. Challenge yourself, see how much you've learned, and identify areas for improvement. Don’t worry, this is all part of the journey to mastery. Ready for the next step? Take a quiz to solidify what you've just studied.