17 Lecture

1. What is the function of the 74xx138 decoder? A) Converts 8-bit code to 3-bit output B) Converts 3-bit code to 8-bit output C) Converts 2-bit code to 4-bit output D) Converts 4-bit code to 2-bit output

Answer: B) Converts 3-bit code to 8-bit output

2. How many inputs does the 74xx138 decoder have? A) 1 B) 2 C) 3 D) 4

Answer: C) 3

3. How many outputs does the 74xx138 decoder have? A) 4 B) 6 C) 8 D) 10

Answer: C) 8

4. What is the maximum number of inputs that can be decoded by the 74xx138 decoder? A) 4 B) 6 C) 8 D) 10

Answer: C) 8

5. What is the active output for the input code 001 in the 74xx138 decoder? A) Y0 B) Y1 C) Y2 D) Y3

Answer: D) Y3

6. What is the active output for the input code 111 in the 74xx138 decoder? A) Y0 B) Y1 C) Y6 D) Y7

Answer: D) Y7

7. What is the function of the enable input in the 74xx138 decoder? A) To enable the decoder to function B) To disable the decoder C) To select the input code D) To select the output

Answer: B) To disable the decoder

8. What is the function of the active-low output in the 74xx138 decoder? A) Inverts the output signal B) Disables the output signal C) Enables the output signal D) None of the above

Answer: A) Inverts the output signal

9. What is the maximum number of output lines that can be enabled in the 74xx138 decoder? A) 1 B) 2 C) 3 D) 8

Answer: C) 3

10. What is the function of the address decoder in a digital circuit? A) Converts binary codes to analog signals B) Converts analog signals to digital codes C) Decodes memory addresses to select a specific memory location D) None of the above

Answer: C) Decodes memory addresses to select a specific memory location

1. What is the purpose of the 74xx138 decoder? Answer: The 74xx138 decoder is used to convert a 3-bit binary code to an 8-bit output.

2. How many inputs does the 74xx138 decoder have? Answer: The 74xx138 decoder has three inputs.

3. How many outputs does the 74xx138 decoder have? Answer: The 74xx138 decoder has eight outputs.

4. How is the active output determined in the 74xx138 decoder? Answer: The active output is determined by the binary code applied to the input.

5. What is the function of the enable input in the 74xx138 decoder? Answer: The enable input is used to disable the decoder.

6. What is the function of the active-low output in the 74xx138 decoder? Answer: The active-low output inverts the output signal.

7. What is the maximum number of output lines that can be enabled in the 74xx138 decoder? Answer: The maximum number of output lines that can be enabled in the 74xx138 decoder is three.

8. What is the function of the address decoder in a digital circuit? Answer: The address decoder is used to decode memory addresses to select a specific memory location.

9. What is the difference between an active-high and active-low output? Answer: An active-high output is activated by a high voltage level, while an active-low output is activated by a low voltage level.

10. What are some applications of the 74xx138 decoder? Answer: The 74xx138 decoder is used in various digital circuits, including address decoding, memory mapping, and control logic circuits.

The 74xx138 is a commonly used 3-to-8 decoder in digital electronics. It is used to convert a 3-bit binary code to an 8-bit output. The input to the decoder is a three-bit binary code, and the output is a corresponding signal on one of the eight output lines. The active output is determined by the binary code applied to the input. The 74xx138 decoder has three input lines, A0, A1, and A2, and eight output lines, Y0 through Y7. When a binary code is applied to the input, the corresponding output line is activated, and a logic high signal appears on that output line. The remaining output lines are set to a logic low signal. The enable input is used to disable the decoder. When the enable input is set to a logic low signal, the decoder is disabled, and all output lines are set to a logic low signal. The active-low output inverts the output signal, which means that when the output is activated, a logic low signal appears on that output line. The 74xx138 decoder is widely used in digital circuits, including address decoding, memory mapping, and control logic circuits. In memory mapping, the decoder is used to select a specific memory location by decoding the memory address. In control logic circuits, the decoder is used to enable or disable various circuit components based on the input code. Overall, the 74xx138 decoder is an important component in digital electronics, and its versatility makes it a valuable tool for various applications.