Digital Circuit Systems

Shift Registers Viva Questions

Shift Registers Viva Questions

Shift Registers Viva Questions, Viva Questions on Shift Registers, Registers Viva Questions Digital Electronics Viva Questions, Engineering Viva Questions, Shift Registers Viva Questions

Flip-Flop Viva Questions

Short Questions and Answers  

Q.1. What do you mean by serial data?

Ans. Multi-bit data is said to be in serial form when the data bits appear sequentially (one after the another in time) at a single terminal.

Q.2. What do you mean by parallel data?

Ans. Multi-bit data is said to be in parallel form when all the bits are available (accessible) simultaneously.

Q.3. What do you mean by serial data transfer?

Ans. serial data transfer is the transmission of one bit of data at a time from one device to another. Serial data must be transmitted under the synchronization of a clock since the clock provides the means to specify the time at which each new bit is sampled.

Q.4. What is a single bit register?

Ans. A flip-flop is called a single bit register. It can store only one bit of data a 0 or a 1.

Q.5. What is a register?

Ans. A register is a set of flip-flops used to store binary data.

Q.6. What do you mean by the storage capacity of a register?

Ans. The storage capacity of a register is the number of bits (1s and 0s) of digital data it can retain.

Q.7. What do you mean by loading a register?

Ans. Loading a register means setting or resetting the individual flip-flops, i.e. inputting data into the register so that their states correspond to the bits of data to be stored.

Q.8. What are the types of loading the registers?

Ans. There are two types of loading the registers. They are (a) serial loading and (b) parallel loading.

Q.9. What is serial loading?

Ans. Serial loading is one in which the data is transferred into the register in serial form, i.e. one bit at a time.

Q.10. What is parallel loading?

Ans. Parallel loading is one in which the data is transferred into the register in parallel form, meaning that all the flip-flops are triggered into their new states at the same time. Parallel input requires that all the SET and/or RESET controls of every flip-flop be accessible.

Q.11. How does a register output data?

Ans. A register may output data either in serial form or in parallel form.

Q.12. What is the serial output?

Ans. Serial output means that the data is transferred out of the register one bit at a time serially.

Q.13. What is the parallel output?

Ans. Parallel output means that the entire data stored in the register is available in parallel form and can be transferred out at the same time.

Q.14. What are shift registers?

Ans. A number of flip-flops are connected together such that the data may be shifted into and shifted out of them are called a shift register. In other words, registers in which the shifting of data takes place are called shift registers. They are used basically for the storage and transfer of digital data. Data may be shifted into and out of the register either in serial form or in parallel form.

Q.15. What is the basic difference between a shift register and a counter?

Ans. The basic difference between a shift register and a counter is that a shift register has no specified sequence of states except in some certain very specialized applications, whereas a counter has a specified sequence of states.

Q.16. What are the applications of shift registers?

Ans. Shift registers are very important digital building blocks. They have innumerable applications. They are used to provide time delays, for serial/parallel data conversion, ring counters, etc. They also form the basis for some very important arithmetic operations.

Q.17. What are buffer registers?

Ans. Buffer registers are registers which are simply used to store data.

Q.18. How will you use a shift register to multiply or divide a binary number by 2?

Ans. The binary number is to be stored in the shift register and then shifted towards the right or left respectively by one-bit position for multiplication or division by 2.

Q.19. What are the basic types of shift registers?

Ans. There are four basic types of shift registers. They are: (a) serial-in, serial-out, (b) serial-in, parallel-out, (c) parallel-in, serial-out, and (d) parallel-in, parallel-out.

Q.20. What is a serial-in, serial-out shift register?

Ans. A serial-in. serial-out shift register is one which accepts data serially, i.e. one bit at a time, and also outputs data serially.

Q.21. What is a serial-in, parallel-out shift register?

Ans. A serial-in, parallel-out shift register is one in which the data bits are entered into the register serially, i.e. one bit at a time but the data stored in the register is shifted out in parallel form i.e. simultaneously.

Q.22. What is a parallel-in, serial-out shift register?

Ans. A parallel-in, serial-out shift register is one in which the data bits are entered simultaneously into their respective stages on parallel lines, but the data bits are transferred out of the register serially, i.e. on a bit-by-bit basis on a single line.

Q.23. What is a parallel-in, parallel-out shift register?

Ans. A parallel-in, parallel-out shift register is one in which the data is entered into the register in parallel form and also the data is taken out of the register in parallel form.

Q.24. What is a bidirectional shift register?

Ans. A bidirectional shift register is one in which the data bits can be shifted from left to right as well as from right to left.

Q.25. What is a universal shift register?

Ans. A universal shift register is a bidirectional register, whose input can be either in serial form or in parallel form and whose output also can be either in serial form or in parallel form.

Q.26. What is a static shift register?

Ans. A static shift register is one in which each of the memory elements used to build the register can retain the data bit indefinitely. So once loaded, the contents of each element of the register remain the same. So a shift register using flip-flops is called a static shift register. In a static shift register data stored is stationary.

Q.27. What is a dynamic shift register?

Ans. A dynamic shift register is one in which the storage is accomplished by continually shifting the bits from one stage to the next and recirculating the output of the last stage into the first stage. The data continually circulates through the register under the control of a clock. To obtain output, a serial output terminal must be accessed at a specific clock pulse, otherwise, the sequence of bits will not correspond to the data stored.

Q.28. Where are dynamic MOS registers used?

Ans. Dynamic MOS registers are widely used as memory devices in digital systems that operate on serial data. Because of their small power consumption and the inherent slowness of the serial systems, they are used in applications where power consumption and physical size are more important considerations than speed, such as in-pocket calculators.

Q.29. Dynamic shift registers are made up of which devices?

Ans. Dynamic shift registers are made up of MOS inverters.

Q.30. What is UART?

Ans. A UART is a specially designed integrated circuit that contains all the registers and synchronizing circuitry necessary to receive data in serial form and to convert and transmit it in parallel form and vice versa. It is an interfacing device.

Q.31. What are the advantages and drawbacks of dynamic MOS registers?

Ans. The main advantages of dynamic MOS registers are their small power consumption and simplicity, which permits a very large number of stages to be fabricated on a single IC. Their disadvantage is that all data transferred must be in serial form, which is much slower than parallel data transfer.

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