Digital Electronics and Computer Organization Important Question Answer for BCA 2nd Semester

Digital Electronics and Computer Organization Important Question Answer for BCA 2nd Semester: this post very helpful for BCA 2nd semester student. in this post we will learn about all the most important questions for BCA 2nd semester. that’s very important for examination purpose. if this post is helpful for you please share this post to your all friends. thanks. if you want to another subject BCA important question and BCA notes you can go this link. BCA Notes.

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Digital Electronics and Computer Organization Important Question Answer for BCA 2nd Semester

1. What are logic gates? Explain different types of gates.

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Logic Gates: Logic gates are electronic devices that perform basic logical operations on one or more binary inputs and produce a binary output based on predefined rules. They are the building blocks of digital circuits and are used to manipulate and process binary information in computers and other digital systems.

Here are some common types of logic gates:

1. AND Gate: The AND gate has two or more inputs and produces an output that is HIGH (1) only when all of its inputs are HIGH (1). Otherwise, the output is LOW (0). The symbol for an AND gate is a triangle with the inputs on the left side and the output on the right side.
2. OR Gate: The OR gate also has two or more inputs, but it produces an output that is HIGH (1) when any of its inputs are HIGH (1). The output is LOW (0) only when all inputs are LOW (0). The symbol for an OR gate is a half-moon shape with the inputs on the left side and the output on the right side.
3. NOT Gate (Inverter): The NOT gate has a single input and produces an output that is the complement of the input. If the input is HIGH (1), the output is LOW (0), and vice versa. The symbol for a NOT gate is a triangle with a small circle at its input and the output on the opposite side.
4. NAND Gate: The NAND gate is a combination of an AND gate followed by a NOT gate. It produces the inverse of the output of an AND gate. The output of a NAND gate is LOW (0) only when all inputs are HIGH (1); otherwise, the output is HIGH (1). The symbol for a NAND gate is the same as an AND gate, with a circle at its output.
5. NOR Gate: The NOR gate is a combination of an OR gate followed by a NOT gate. It produces the inverse of the output of an OR gate. The output of a NOR gate is HIGH (1) only when all inputs are LOW (0); otherwise, the output is LOW (0). The symbol for a NOR gate is the same as an OR gate, with a circle at its output.
6. XOR Gate (Exclusive OR): The XOR gate has two inputs and produces a HIGH (1) output when the number of HIGH (1) inputs is odd. If both inputs are the same (both HIGH or both LOW), the output is LOW (0). The symbol for an XOR gate is a plus sign (+) with a circle at its output.

These are the fundamental logic gates, and they can be combined to create more complex logic functions and circuits. By combining these gates in various ways, complex digital systems can be built to perform calculations, make decisions, and control the operation of electronic devices.

2. Explain the K-Map.

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• A Karnaugh Map (K Map) is a pictorial method used to minimize boolean expression s without having to use boolean algebra theorems and equation manipulations. A K Map can be thought of as a special version of a truth table.
• K Map is a gird-like representation of a truth table. It is really just another way of presenting the truth table.

3. What do you understand by combinational circuit?

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Combinational Circuit:

A combinational circuit is the digital logic circuit in which the output depends on the combination of inputs at that point of time with total disregard to the past state of the inputs. The digital logic gate is the
building block of combinational circuits. The function implemented by combinational circuit is depend upon the Boolean expressions. On the other hand, sequential logic circuits, consists of both logic gates and memory elements such as flip-flops. Figure below shows the combinational circuit having n inputs and and m outputs. The n number of inputs shows that there are 2^n possible combinations of bits at the input. Therefore, the output is expressed in terms m Boolean expressions.

4. Describe the following terms:
i) ROM
ii) PROM
iii) EPROM
iv) RAM
v) Virtual Memory

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i) ROM (Read-Only Memory): ROM is a type of non-volatile memory that stores data permanently. The data stored in ROM cannot be modified or erased by normal computer operations. It contains instructions or data that are essential for booting up the computer system. The content of ROM is typically pre-programmed during manufacturing and remains unchanged throughout the life of the device. Examples of ROM include firmware in electronic devices and the initial boot-up instructions in a computer.

ii) PROM (Programmable Read-Only Memory): PROM is a type of memory that can be programmed by the user after it is manufactured. It is initially blank and can be programmed using a PROM programmer device. Once programmed, the data in PROM becomes permanent and cannot be changed. The programming process is irreversible, meaning the stored data cannot be erased or modified. PROMs are used to store data or instructions that need to be permanently retained, such as firmware or low-level software.

iii) EPROM (Erasable Programmable Read-Only Memory): EPROM is a type of memory that, unlike PROM, can be erased and reprogrammed multiple times. It retains the stored data even when the power is turned off. However, to erase the data in EPROM, it requires exposure to ultraviolet (UV) light for a specified period. EPROM chips have a small window on top that allows the UV light to reach the memory cells. Once erased, new data can be programmed onto the EPROM. EPROMs are useful for development purposes or situations where the stored data needs to be changed occasionally.

iv) RAM (Random Access Memory): RAM is a type of volatile computer memory that provides temporary storage for data that is actively being used by the computer. It allows quick read and write access, making it ideal for storing data that needs to be accessed randomly and frequently by the CPU. Unlike ROM or PROM, RAM is not permanent and loses its content when the power is turned off or the computer is restarted. RAM is an essential component of a computer system, and its size and speed greatly affect system performance.

v) Virtual Memory: Virtual memory is a technique used by operating systems to expand the available memory beyond the physical RAM installed in a computer. It allows programs to use more memory than is physically available by utilizing a portion of the hard disk as an extension of the RAM. The operating system manages virtual memory by transferring data between RAM and disk storage as needed. Virtual memory enables multitasking and the execution of larger programs by providing a larger addressable memory space. However, accessing data from virtual memory is slower than accessing data from physical RAM, as it involves disk read/write operations.

5. What do you understand by Adder? (Half adder and Full adder).

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6. Define universal gates.

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7. What do you mean by encoder? Explain.

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8. What do you mean by Multiplexer?

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9. Draw K-Map and simplify the following Boolean expression:
Y(A,B,C,D) = Σ(0,2,4,6,8,10,12,14,15)

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10. What do you understand by memory? Write a short note on primary memory.

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11. What do you mean by RAM? Explain the difference between static and dynamic ram.

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12. Draw the logic diagram and truth table of the following flip flops.
(a) R-S flip flops
(b) J-K flip flops
(c) D flip flops
(d) T flip flops.

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13. What is a Ring counter? Explain.

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14. What do you mean by state table and state diagram?

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15. What do you mean by shift registers?

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16. State and verify De Morgan’s Law in following Boolean algebra.

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17. Explain hard disk and floppy disk?

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18. What is a sequential circuit? Define flip flops.

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